Original subtitles

ROWE: The night sky.

Countless stars and the majestic sweep

of the Milky Way, but beyond our local neighborhood,

across the cosmos, there are over

two trillion more galaxies.

THALLER: When we first began to observe galaxies,

we collected them like butterflies.

Little by little, we realized that

they formed a web.

ROWE: The cosmic web is the infrastructure that connects

every corner of the universe.

You don't know anything about our universe

if you don't understand the cosmic web.

It feeds galaxies. It forms galaxies.

It is made of galaxies.

ROWE: It's the architect of everything,

and our cosmic future depends on it.

The cosmic web is one of the most important parts

of our universe -- It plays a key role

in the evolution of the cosmos.

Without the cosmic web, there would be no stars,

no planets, nowhere in the universe where

the conditions of life could exist.

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

to a cosmic web, sprinkled with galaxies,

planets, and us?

The universe may appear random.

Two trillion galaxies, spread across the cosmos.

But in this cosmic chaos,

scientists detect water.

When we first saw that the universe was full

of galaxies, it seemed like overwhelming chaos,

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

ROWE: Galaxies link up in a gigantic cosmic network

spanning the entire universe.

How this pattern emerged may be cosmology's

biggest puzzle.

In some senses, you don't understand something

unless you understand how it comes into existence

and how it's formed.

And galaxies are the basic building block

of our universe.

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

to the very edge of the observable universe,

and study light from the first galaxies.

Chile, 2021.

Scientists point the VLT, or Very Large Telescope,

towards the Hubble Ultra Deep Field.

It's a patch of sky famously photographed

by the Hubble Space Telescope in 1995.

The VLT's power allows astronomers to see

much deeper into space.

Imagine you take a grain of sand,

and you put it on your fingertip,

and you hold your arm out like this,

and you block a part of the sky looking

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

of the Hubble Ultra Deep Field, and yet it contains

thousands of galaxies in it.

ROWE: The telescope stares at those galaxies

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

ancient hydrogen gas concentrated along a strand

of space 15 million lightyears long.

The filaments are just one tiny section

of the cosmic web, the largest known

structure in the universe.

The scale of the cosmic web is enormous.

It is, by definition, the largest thing

that we can see in our universe.

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

linked streams of hydrogen gas

that form an intergalactic network spanning

the entire universe.

Inside the nodes of the cosmic web,

you'll find galaxies and stars and black holes.

Along the filaments, you'll find gas

that connects these nodes, and the gas will connect

to the other galaxies and clusters of galaxies.

It's this beautiful superhighway of

large cities that are connected through these filaments.

BULLOCK: We can see the cosmic web

about as far back as we can look,

and really, galaxies are forming along that web

all the way back.

ROWE: This cosmic infrastructure dates back

to the earliest days of the universe.

13.8 billion years ago,

the universe ignites in a tiny ball

of super hot energy.

It expands and begins to cool.

Energy transforms into primitive,

subatomic particles of matter.

The heat from the Big Bang is so intense,

gravity is effectively powerless.

The very early universe was super hot,

super energetic, and regular particles

of matter were zipping around so fast

that not even gravity could hold them together.

But regular matter wasn't the only thing

in the early universe.

ROWE: In the background, gravity is working

on something else --

Regular matter's ghostly cousin,

the invisible substance known today as dark matter.

It makes up about 85 percent of all the matter

created in the early universe.

Normal matter and dark matter both existed

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

was very different.

ROWE: Just ten seconds after the Big Bang,

the infant universe is billions of degrees Fahrenheit,

still far too hot for regular matter particles

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

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

radiation in the same way that regular matter is,

and so because it's able to cool,

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

ROWE: As dark matter clumps grow, they exert

a gravitational pull and begin to form shadowy structures.

As soon as the dark matter gets a foothold,

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

then that attracts more and more dark matter.

ROWE: 380,000 years after the Big Bang,

the intense heat drops to a few thousand degrees.

Normal particles of matter move around more slowly.

Protons and electrons bind together and form

atoms of hydrogen and helium gas.

Then gravity from dark matter starts to work

on regular matter.

Before you know it, you have this very clumpy

universe with these huge dark matter halos

that can now start to draw in also ordinary matter

in the form of gas.

ROWE: A billion-year building project begins.

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

the foundations of the cosmic web and the galaxies.

Just as when you build a building, you know,

there's a lot of work that happens before

the building goes up, our universe spent

a lot of time laying the groundwork for

this cosmic web before it switched on the lights.

ROWE: The foundations are complete,

but the job isn't finished.

How did those clouds of gas transform into the greatest

structure in the universe?

The secretive dark matter that brought the gas together

is also on site, managing the build.

It was really the dark matter that called the shots

in cosmic clustering, because it outweighed

the ordinary stuff by a big factor.

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

Tendrils of material are stretched out across the cosmos.

ROWE: As the sprawling structure builds, its gravitational

pull strengthens, pulling in more dark matter.

The clumps begin to collapse and shrink down

into filaments -- these meet at even more tightly

packed clusters, creating a huge, dark scaffold

that drags in more hydrogen gas.

BULLOCK: Imagine drops of dew on a spider web.

That's like hydrogen blobs being pulled in

to dark matter's cosmic web.

ROWE: After tens of millions of years of construction,

strands of gas stretch across the cosmos.

Fast forward to now -- The web appears

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

We know at some point, stars and galaxies formed.

The big question is when -- What were the first

galaxies like? That's a big mystery.

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

Evidence suggests that as the universe assembled its web

of dark matter and hydrogen gas,

the biggest stars that have ever lived

set the cosmos ablaze.

ROWE: 2018, scientists study an ancient galaxy,

the catchily named MACS1149-JD1.

There, they find some of the oldest stars

ever detected.

This particular galaxy is exciting, because it's

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

ROWE: Those stars could hold clues as to how

the cosmic web that supports the universe

first lit up, but as astronomers study

starlight from when the universe was just

250 million years old, they get a shock.

The stars are not just made up of hydrogen

and helium produced in the Big Bang.

They also contain what astronomers call metals.

Metals in astronomy is everything heavier

than hydrogen and helium.

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

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

even though that makes no sense.

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

NANCE: The Big Bang only made hydrogen and helium.

Anything heavier than that was churned up in

the cores of dying stars.

ROWE: The bright stars of this ancient galaxy

dating back to just 250 million years after

the Big Bang contain chemicals that were created

in even earlier stars.

Some of them seem to be nearly the age of

the universe, extremely old, and yet they contain

elements that guarantee they can't have been

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

there must have been something that came before.

ROWE: The earlier first generation of stars

remains cloaked in mystery.

How did the first stars ignite,

and did they kickstart the formation

of the first galaxies?

It sounds like a classic creation myth,

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

structure arrived, and from that structure,

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

ROWE: We've never seen a first-generation star,

but physicists have a theory of how they formed

and what they were like.

Let's step even further back in time,

to around 100 million years after the Big Bang.

The early cosmic web is dark.

There are no stars to illuminate it.

But the universe is ready for stellar ignition.

Cooled down after millions of years of expansion,

the gas clouds clinging to the dark matter scaffold

begin to contract.

As the hydrogen gas clumps together,

larger clouds form super dense,

ultra hot cores.

THALLER: If you can bring hydrogen together,

and actually get it hot and dense enough,

hydrogen will begin to fuse into helium.

There will be a nuclear fusion reaction going on.

ROWE: Simulations suggest that some gas clouds are

hundreds of times the mass of the sun.

The stars they produce

are unlike anything that exist today.

So the stars around us today really top out at masses

between let's say 70 to 100 times the mass of our sun.

There's nothing larger than that.

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

more massive than the sun, so if you plopped it

in our solar system, it would extend

all the way past Jupiter -- So think about that.

That is incredibly big.

That scale is mind-blowing.

ROWE: So what happened to these stellar behemoths?

THALLER: The lifetime of a star has a lot to do with its mass.

The more massive a star is, the more gravity crushes

the interior up to high temperatures, and it burns

through its nuclear fuel even faster, so incredibly,

the more mass there is, the shorter a lifetime

you get for a star.

OLUSEYI: The first generation of stars are sort of like

the rappers and rock stars of the universe.

They live fast, they die young.

ROWE: First generation stars didn't live long enough

to form complex galaxies, but they did set

the process in motion.

The lives of the first stars may have been rock and roll,

but their explosive deaths and supernovas

pump the universe full of heavy metal.

THALLER: In the galaxy today, we see a supernova

maybe every couple of years, close to us every

couple of decades -- this must have been a fireworks show,

giant supernovas going off all the time, all around you.

OLUSEYI: That act of destruction is actually an act of creation.

What a star does in its core is it creates

heavier elements from lighter elements.

THALLER: That first generation of stars must have been

absolutely incredible, simply exploding

so quickly and unloading all of this wonderful new chemistry

into the galaxy.

ROWE: 200 million years after the Big Bang,

the remains of the first stars flood the interstellar medium

with heavier elements, like carbon, oxygen,

silicon, and iron,

crucial ingredients for the next wave of stars.

It's such a beautiful story, because suddenly the whole

process of star formation changed,

and it literally became easier to make a star.

ROWE: Heavy elements suck heat out of the surrounding gas.

Cooler clouds crunch down must faster.

The smaller, second-generation stars form rapidly

and in much greater numbers.

Somehow, this mess of stars transformed into a network

of young galaxies, but it wasn't easy,

because as these baby galaxies formed,

a breed of matter-hungry monsters

appeared in the young cosmic web.

ROWE: 13.6 billion years ago, the dark scaffold

that supports all the regular matter in the universe

emerges, ablaze with stars.

But how did this stellar array evolve into a structure

littered with organized galaxies?

It seems they formed under constant threat of destruction.

October 2020.

Astronomers discover a monster lurking

among the cosmic web's earliest structures,

dating to 900 million years after the Big Bang,

a supermassive black hole.

Six galaxies surround this cosmic giant,

caught in its grip, seemingly linked to

the supermassive black hole by filaments

of the developing cosmic web.

It's like the universe has given supermassive black holes

an umbilical cord.

It's like an all-you-can-eat buffet, right there.

ROWE: Supermassive black holes are hungry beasts.

They feast on any matter that gets too close to them.

MINGARELLI: Supermassive black holes are likely some of

the most powerful objects in the universe.

They can be anywhere between 100,000 to 10 billion

times the mass of the sun.

ROWE: Supermassive black holes have been a nemesis

for generations of scientists, not because of

their fearsome nature, but because nobody knows

how they grew so large, so early.

SUTTER: I wish I knew where supermassive black holes

came from -- if I knew, I would have a Nobel Prize

hanging around my neck, and I would wear it

every single day.

As someone who deeply loves supermassive black holes,

whose career is based on studying supermassive

black holes, it is very frustrating to not

know where they come from.

ROWE: Regular stellar black holes are the collapsed

cores of dead stars, ranging from

three to thousands of solar masses,

but supermassive black holes, those are a different beast.

Thirteen billion years ago, not enough stars

had lived and died to build something as huge

as a supermassive black hole.

Now, the cosmic web offers scientists clues

about the black hole conundrum.

We now know supermassive black holes grow

among the lattice of the young cosmic web,

gorging on the hydrogen gas that travels along the filaments.

At the same time, when the cosmic web

is lighting up, supermassive black holes

appear to be stealing star fuel from the young universe.

You might think that would kill a growing galaxy,

and yet most mature galaxies have a supermassive black hole.

They really dominate the physics of what happens

in the centers of galaxies, and even how galaxies

can evolve.

ROWE: We think these galactic monsters have been around

from the start -- How then did the web's

young galaxies develop around supermassive black holes?

The Milky Way's supermassive black hole is called

Sagittarius A-Star.

It's around 27 million miles wide and weighs in

at just over 4 million solar masses.

MINGARELLI: The environment around Sagittarius A-Star

is very dynamic -- It can actually be

a really hellish place -- There's this accretion disk

that's full of plasma, it's heated to

thousands of degrees, so you wouldn't necessarily

think that that's a great place for star formation

to happen.

ROWE: But that's exactly where astronomers

decided to look.

Using the Atacama Large Millimeter Array,

or ALMA for short, scientists scan

the heart of the Milky Way for dense cores of gas and dust,

stellar embryos.

They found more than 800 within just a thousand lightyears

of Sagittarius A-Star,

including more than 40 embryos with energetic jets

blasting from their cores, the telltale sign

of the birth of stars.

MINGARELLI: It's really surprising to find

those stars there -- It's like hearing

babies' cries from a wolf's den.

PLAIT: It's not the place you would expect this to happen,

but in fact, stars are forming there.

Now, it's not as efficient as it is out here

in the suburbs where things are quieter, but it works.

ROWE: Baby stars igniting and thriving around

a supermassive black hole, the kind of

hostile environment we know existed in the young

cosmic web -- Star birth is a key part

of kickstarting young galaxies.

This evidence suggests that star formation

is more resilient than researchers thought,

and they've developed a theory to explain it.

Gas and dust race around the black hole

in the accretion disk -- Heated to incredible

temperatures, plumes of gas break off

and blast into space.

The gas rapidly cools, collapses,

and forms baby stars -- These accretion disks

are the most chaotic of stellar nurseries.

You see this mechanism that you think is violently

inhibiting star formation, and at the same time,

it's triggering the birth of new stars.

ROWE: Matter clumps at the cosmic web's intersections,

feeding the supermassive black holes.

Around them, stars burst into life,

slowly building galaxies.

This could be how our own Milky Way formed

among the filaments of the young cosmic web.

But new research suggests that growth in these baby galaxies

requires murder and mayhem, and without them,

we wouldn't exist.

ROWE: The infant universe is a dramatic place.

Stars ignite, and stars die,

even in the violent surroundings of supermassive black holes.

Baby galaxies form with the cosmic web.

But how do they grow?

Scientists believe the critical factor is galactic turmoil.

The universe does need to churn things up.

You need to break some eggs to make an omelet.

You need to introduce some chaos into your galaxy

to rapidly form stars or grow black holes.

Smashing things together is how the universe came to be.

ROWE: The Hubble Space Telescope discovers many distorted

galaxies -- twisted, battered, and torn,

victims of violent collisions on a cosmic scale.

HOPKINS: Galaxies are never sitting quietly, doing nothing.

They're always undergoing change -- they're constantly

encountering and slamming into and colliding with

and mixing with other galaxies.

MINGARELLI: You can see images in Hubble

of total car wrecks, of galaxies that are

trying to merge with each other.

ROWE: We know that galaxies collide now,

but what about in the early universe,

when the cosmic web was beginning to take shape?

Astronomers study a strange galaxy named Himiko,

born just 800 million years after the Big Bang.

Three bright light sources suggest intense star formation.

Detailed analysis reveals not one galaxy,

but three baby galaxies, not yet fully formed.

Scientists call these youthful star systems protogalaxies.

The trio that make up Himiko are in mid-collision.

Computer simulations of the early universe suggest

protogalaxies smashed together with frightening regularity.

These violent shake-ups trigger star birth.

Protogalaxies are rich in gas,

and when they collide and merge, those gas clouds

collide and collapse and form stars,

sometimes, at prodigious rates, and after a billion years

or so, all of that structure forms, and you get

a formal galaxy.

ROWE: Picture the early universe,

500 million years after the Big Bang.

It's smaller and more compact than today.

Cosmic collisions are common.

PLAIT: Imagine taking a bunch of cars and just letting them

drive around in Nevada where

there's nothing but space, right?

You're not gonna get too many collisions.

Now squeeze them into a tiny little city block

some place, and you're just gonna have accidents everywhere.

Well, it's the same thing with the universe.

When the universe was younger, it was smaller,

and these protogalaxies were everywhere.

It was crowded.

You were bound to get collisions between them back then.

ROWE: More and more baby galaxies form at the growing

web's gas-rich intersections.

A collision between small protogalaxies

might trigger modest amounts of star formation

when regions of dense matter come together.

But a merger involving

protogalaxies with rich reserves of gas

can rev up the rate of stellar ignition,

supercharging a growing galaxy.

Gas-rich mergers can generate starburst galaxies,

where we see incredibly vigorous events of star formation.

ROWE: Astronomers think one such smash-up,

around 10 billion years ago, kickstarted the growth

of the Milky Way.

A group of stars called the Gaia Enceladus Cluster

in the outer reaches of the galaxy

behaves strangely compared to other stars around it.

SUTTER: The stars in the Gaia Enceladus Cluster,

they're different, they move differently,

they act different, they're like -- they're like

kids from the next town over showing up at your school.

You just know that they don't belong.

The Milky Way had already largely formed,

and then this massive cluster comes screaming in.

It was a violent event

that eventually ended up absorbing the stars

from this cluster into the body of

the Milky Way itself.

Galaxies are built from these kinds of collisions.

ROWE: Less than a billion years after the Big Bang,

the dark scaffold of the cosmic web begins to glow.

Matter channeled down the web's tendrils creates

dense clumps of gas -- Even in the turbulent

neighborhoods of supermassive black holes,

stars burst into life.

Baby galaxies collide, and the young universe

sparkles with light.

But an important question remains.

In the mayhem of the early universe,

how did galaxies like our Milky Way

survive and thrive?

MINGARELLI: Galaxy evolution is very dynamic.

Our understanding of galaxy evolution is very dynamic,

and there's so much that we still don't know.

There's a lot of different competing theories

right now as to how galaxies grew into the galaxies

that we see today.

It's a huge open question, and it's something that's

a big deal in science right now.

ROWE: New research suggests that life and death

in the cradle of the universe lay within

the cosmic web.

ROWE: 13.6 billion years ago,

a protogalaxy, the infant Milky Way,

forms in the tendrils of the young cosmic web.

Today, it bears the scars

of many collisions.

Each one could have torn it apart.

So what controls if a young galaxy lives or dies?

May 2020.

Scientists image a graceful galaxy that existed

just 1.4 billion years after the Big Bang.

Analysis of its light shows this

is a starburst galaxy, pumping out newborn stars.

Galaxies like our Milky Way are old and rather stately,

and they don't form stars very rapidly --

About the equivalent of the mass of the sun every year.

Well, starburst galaxies -- Yeah, they form them

a lot more quickly -- hundreds of solar masses per year.

But BRI 1335-0417,

4,650 times the mass of the sun every year.

It is blasting out stars.

ROWE: Some young galaxies in the early universe

appear to be supercharged with star fuel.

How can they grow at such an incredible pace?

Scientists think the answer lies in the mysterious substance

that's controlled the flow of gas since the beginning --

The dark structure whose tendrils stitch

the universe together,

but exploring this cosmic network is no easy task.

When it comes to dark matter,

we're flying blind.

May 2021.

An international team of researchers investigates

dark matter in the local universe by observing

its effect on the path of light.

Gravity affects light.

A massive object causes light to curve

through space, even if that object is invisible,

like dark matter.

We can't see the dark matter directly, but we can see

what it's doing to the light -- It's stretching it,

it's bending it, it's creating arcs in ways

that would never happen unless the dark matter were there.

ROWE: Using an AI program,

the team analyzes 100 million visible galaxies,

looking for warped galactic light.

Because the model is artificially intelligent,

it gets better and better at finding dark matter.

What's very clever about this kind of algorithm

is that it's learning as it goes.

It uses the information that it has

to predict the existence of new structures.

ROWE: As the model teaches itself to see

the dark matter behind the stars,

it maps out new, dark structures,

never-before-seen highways between galaxies.

There's a lot more filaments, there's a lot more

intricacies, there's a lot more cosmic web there

than what meets the eye.

It's like if you look how

Manhattan is connected to the land around it,

you can see all the bridges, but now we're also seeing

the underwater tunnels.

ROWE: The new layout of dark matter reveals

the local universe is a bird's nest of hidden channels,

feeding galaxies with gas.

Galactic structures seem to thrive

at the cosmic web's most densely-knotted intersections.

Because multiple filaments are intersected

in those locations, and that is a location

of very enhanced gravity relative to other locations,

the material will be drawn in,

so these galaxy clusters are likely feeding off

the cosmic web.

ROWE: This connectivity could be the key to the rapidly-forming

galaxies in the early universe, but there's a catch.

Sitting right at the densest regions of

the cosmic web can be really good for galaxy growth.

You have all of this gas being funneled in

for a new star formation, but being that plugged in

to the network isn't all good news.

ROWE: There is evidence that, though the cosmic web

gives life, it can also take life away.

Scientists studying some of the universe's most heavily

connected galaxies found something unexpected --

Plummeting rates of star birth.

In some ways, it's a little bit counter-intuitive, right?

If these nodes are meeting grounds for all of

this gas, right, why aren't you forming more stars there?

ROWE: One explanation? In the all-you-can-eat buffet

of the cosmic web's matter-rich junctions,

a young galaxy might over-indulge.

As the cosmic web funnels more matter towards a junction

and its growing galaxies, the gas influx doesn't

just boost star formation, it fattens up

the supermassive black hole at the galaxy's core.

For a young galaxy, that's dangerous,

because when this monster over-eats, it produces

high-energy jets and belches out

super hot wind.

These black holes radiate tremendous amounts of energy

when they grow, and that radiation can

slam into the material around them in the galaxy

and blow it all out of the galaxy, launch it away

or heat it up to super high temperatures.

Star formation requires stuff, so if you blow that stuff

away, how are you gonna form a star?

And what's left behind would be what we call

a quenched galaxy that basically can't form any new stars.

ROWE: The researchers found that although connectivity

within the cosmic web can boost galactic growth,

it was the super connected galaxies that died

the quickest, choked and stunted like over-watered plants.

Perhaps our Milky Way got lucky.

You could say that the Milky Way Galaxy is sort of

in this Goldilocks zone of galaxy formation.

It's been receiving enough gas over time that it's

been able to keep up with its star formation

but not so much gas that its central black hole

has been fed enough that it would clear the galaxy

out of gas.

ROWE: The cosmic web determined if galaxies lived or died.

Its construction project brought order to chaos.

The cosmic web is the architect, the engineer,

the builder, the construction worker, even the interior

designer of the cosmos.

ROWE: But now, work has shut down.

An invisible force threatens to tear apart the very

fabric of the cosmic web -- What does this mean

for galaxies and for us?

ROWE: The cosmic web brought order to the early universe.

The gravitational attraction of its dark scaffolding

helped build galaxies and fueled their development.

But growth tops out at the level of galaxy clusters.

Nothing bigger will ever form.

Something has stopped the formation of structure

in our universe.

ROWE: To understand what's going on,

we need to return to the Big Bang

and the formation of the cosmic web.

13.8 billion years ago, the universe sparks into life.

A tiny ball of pure energy cools and expands.

The energy transforms into regular matter

and dark matter, but another force appears

at the same time -- dark energy.

Dark energy, as far as we understand it,

which is not much, has always been here.

It's always been a part of the universe,

but it's been silent, in the background.

Dark energy is everywhere -- It's over here,

it's over there, it's between you and me.

It's absolutely everywhere.

One theory is that dark energy never formed,

that it's just a constant in the laws of physics

that has always been there and always will be.

ROWE: Some physicists believe that dark energy

is simply the force of emptiness.

TEGMARK: People used to take for granted that space was empty,

a vacuum, but the discovery of dark energy

has made some people wonder if space is actually

more of a substance, and, um, that space also

might have pressure that causes things

to push apart, so, you know, whatever space is,

it might be more interesting than we thought.

ROWE: Dark matter dominates the young universe,

but as the dark scaffold of the cosmic web grows,

it sows the seeds of self-destruction.

As the network of matter takes shape,

pockets of emptiness form between the filaments --

Cosmic voids.

In these expanding hollow spaces, dark energy grows.

The weirdest thing about dark energy is that

it has constant density -- Constant density means

the more volume you have, the more dark energy you have,

so the larger the voids get,

the more dark energy they contain.

ROWE: Dark energy pushes against the cosmic web,

opening up huge chasms in

the architecture of the universe.

Five billion years ago, dark matter's strength of

attraction is finally overwhelmed.

Like bridge cables in a hurricane,

the cosmic web's filaments stretch and snap,

and the universe's substructure fails.

Galactic construction freezes as the universe expands,

but darker times are ahead for the cosmic web.

As time goes on, not only is it expanding,

but this expansion gets faster and faster and faster.

ROWE: As the dark energy in the voids increases,

the entire structure of the cosmic web

begins to break up.

The effects of dark energy will get stronger

and stronger with time, until the very fabric

of space time gets torn apart.

This isn't a superhero movie -- The bad guy wins.

The future of the cosmic web is looking bleak.

Ultimately, it's gonna be

a cold, lonely universe.

ROWE: Our closest galaxies will accelerate away,

until they're just tiny pinpricks of light.

Then the universe will go dark again.

Everything will fade out.

So the universe started with a bang,

but it will die with a whisper.

ROWE: The cosmic web transformed the universe

from a hot mess to a sparkling structure.

It gave birth to billions of galaxies and us.

Without it, space would be

a much less interesting place.

This giant structure, the largest thing that we know of

in the universe, is responsible for nourishing the galaxies,

creating the stars, making the conditions right

to form life -- we would not be here, talking right now,

if it were not for this cosmic web.

SUTTER: Understanding the cosmic web

is understanding dark matter, is understanding dark energy,

is understanding our past, is understanding our future.

Really, everything that we know about how the universe works

is directly tied to the cosmic web.

It's amazing to think that the overall structure of

the universe that we witness today began in the earliest

times of the universe and has yielded

beings like ourselves who can now

discover it and ponder about its existence.

That's pretty dope.