All language subtitles for Provan

Astronomers have begun one

of the most far-reaching efforts

ever undertaken to study the universe.

They are forging giant
new lenses and mirrors

- while marshaling vast
- computational power.

These new technologies are at

the center of a historic quest

- to peer into the deepest
- recesses of time

to find out how the universe set the stage

for galaxies and worlds like ours

in an era known as the Cosmic Dawn.

Felipe Menanteau and colleagues from

the University of Illinois are part

of a global push to advance
the science of cosmology,

the study of the universe as a whole.

They are mapping the positions of galaxies

across the sky and extending
deep into the universe.

So, that was only at the end, can you.

Their goal, to link the evolution

of planets, stars, and galaxies,

the universe we see around us,

with conditions that
existed at the dawn of time.

What forces came together
to form the first

generation of stars and galaxies,

and over time, the vast architecture

of matter and light we
see in our telescopes?

Only a century ago, astronomers debated

whether the universe
is confined to a giant

rotating disk of stars, dust, and gas,

the Milky Way,

or whether our galaxy is one of many

so-called island universes.

We now know that our galaxy
is part of a formation

of three major galaxies,

along with some 51 dwarf
galaxies called the Local Group.

The Local Group is bound by gravity

to a much larger formation,

the Virgo Cluster, with
up to 2,000 galaxies.

Beyond Virgo, galaxy clusters
are linked to superclusters

in a pattern laid out by the first great

cosmic mapping project: the
Sloan Digital Sky Survey,

beginning in the year 2000.

As the Sloan data shows,

superclusters are connected to each other

by streams or filaments of galaxies

bounded by immense empty regions.

To understand how the
universe got this way,

astronomers must identify
its basic components

of matter and energy.

Back in the 1930s,

the astronomer Fritz Zwicky measured

the rotation rate of spiral
galaxies like the Milky Way.

He found that the gravity
that binds their stars

is over 100 times greater
than what he expected

based on the amount of
matter that's visible.

Zwicky called the unseen substance

exerting this extra
gravitational pull dark matter.

You can see its influence
on even larger scales.

Without dark matter,

the gravity of clusters like this

is not enough to hold all the
galaxies rotating around it.

In this case, dark matter acts as a lens,

magnifying and distorting
the light of galaxies

in the deep background and causing

them to appear as blue arcs.

Astronomers use the pattern
of gravitational lensing

to map the distribution of dark matter

in the supercluster Abell 1689

shown here as a blue haze.

On a large scale,

galaxy structures like these are a measure

of how much dark matter there is.

One of the tools that we have in cosmology

to pin down the kind of
universe that we live in

is the growth of the structures.

These are giant systems with hundreds

of thousands of galaxies

and these systems,

these ones are particularly
big, are very, very rare

and the number of those that you can find

as a function of cosmic time,

you know, from here to the past,

depends,

it's a very strong prediction

of the universe that we live on.

This computer model

shows the role of dark matter has played

in shaping the contours of the universe.

Not long after The Big Bang,

gravity began to amplify
slight initial variations

in the distribution of dark matter.

Regions of the highest density

attracted enough visible
matter to form galaxy clusters

and the largest superclusters.

Even as astronomers struggle to define

what dark matter is,

they discovered another mysterious

and powerful influence
on cosmic evolution.

In the late 1990s, two
groups of astronomers asked

whether there's enough
dark matter out there

to one day slow, or even halt,

the expansion of the universe.

Using the Hubble Space Telescope,

along with ground-based telescopes,

the team set out to track
the rate of cosmic expansion

through the entire
history of the universe.

They did this by searching deep space

for a particular type of exploding star

called a Type Ia Supernova,

it often begins with two
stars in a close orbit,

one of which draws gas
from its companion.

When it gains enough mass,

it undergoes a runaway
nuclear reaction and explodes.

Because Type Ia supernovae are all thought

to blow up in the same way,

they have the same intrinsic brightness

That makes them ideal for
measuring cosmic distances.

It's like looking at car headlights

approaching on a highway.

The dimmer they appear,
the farther away they are.

The astronomers combined distance

measurements with another marker:

how far their light had shifted

toward the red part of the light spectrum.

The greater this red shift,

the more the universe had
expanded since the star exploded.

Some explosions appeared
dimmer than the teams expected

based on their red shift.

That meant their light had traveled

farther than it should have,

given a constant rate of expansion.

This finding led the two teams

to conclude that in the deep past

the universe was slowing down

but to reach its current size

it must have then sped up.

Scientists now believe
the universe is dominated,

not by matter we can see

nor by the mysterious gravitational
presence, dark matter

it's something else,

pervasive and powerful enough

to cause space to accelerate outward.

They call it dark energy.

One leading idea is that
it stems from particles

that well up from the vacuum of space.

As the universe expands,

it generates more and more dark energy.

That has the effect, over large distances,

of counteracting gravity and causing space

to expand even faster

Spread over the vastness of the universe,

it is the energy equivalent of only

five hydrogen atoms per cubic meter

And yet scientists find that dark energy

accounts for 68% of the entire
cosmic matter energy budget

with dark matter at 27%

and ordinary visible matter, less than 5%.

The twin discoveries of
dark matter and dark energy

have thrown cosmology into turmoil

and potentially, into
a new age of discovery.

Astronomers have now
launched a full-scale effort

to pin down the forces and events

that drove cosmic evolution going

back to the earliest times.

Already a fleet of space
telescopes led by Hubble

is scanning the distant universe

for light sources across the
electromagnetic spectrum.

The long-awaited James
Webb Space Telescope

slated for launch in 2018

represents the next generation
of great space observatories.

With a segmented primary mirror

that is almost three times
larger than that of Hubble,

the James Webb will capture
the trickle of photons

from a time nearly 13 billion years ago

when the universe lit up
with stars and galaxies.

The next generation of ground telescopes

will radically extend our
light-gathering power.

The European Extremely Large Telescope,

now under construction in
Chile's Atacama Desert,

will have a 39-meter mirror

that quadruples the light-gathering power

of the largest telescopes today.

While these telescopes extend

our vision into the deep universe,

the American WFIRST and the
European Euclid space telescopes

will take in large regions of
the sky at high resolution.

These new instruments, each
slated for launch in the 2020s,

will be used to survey the deep universe

for Type Ia supernovae

and other markers of cosmic evolution.

These space observatories
will work in conjunction

with an ambitious new effort to track

the evolution of the
cosmos in near real-time.

The Large Synoptic Survey
Telescope, or LSST,

is being built in the mountains of Chile.

It combines data gathering
on a unprecedented scale

with plans for dedicated
fiber optic connections

capable of delivering a flood of data

to supercomputers a continent away.

From there, it will be processed

and made available through
advanced internet links

to scientists around the world.

At its heart, the LSST will be outfitted

with the largest digital
camera ever built.

I don't see any leaks.

That includes the largest lens ever built,

now undergoing final
polish before assembly.

- Looks good, huh?
- Yeah.

With a field of view the size of 50 full moons,

the telescope will observe
just over half the sky

visible from the Earth to a depth of about

halfway back to the beginning of time.

- LSST is going to take
a new image of the sky

in roughly every 47 seconds,

and so, for us to bring
the picture of the sky

to the world as quickly as possible,

we are going to release a catalog of how

the universe appears to
have changed with time

within one minute of that shutter closing.

And so every 47 seconds,
every night for 10 years,

we're going to distribute effectively

in many worldwide data release

of how the sky looks like
it changed with time.

And on average, LSST will
image the entire southern sky

roughly once every several days.

Astronomers expect a telescope

to record a blizzard of transient events,

from asteroids buzzing
through the solar system,

to black holes flaring
up in distant galaxies,

and stars exploding out on the
horizons of space and time.

The telescope will revolutionize

what scientists call
Time Domain Astronomy.

- Right now, there are lots of
Time Domain Series going on,

and worldwide, you might
get thousands of new

alerts per night of things
that have changed in the sky,

but LSST will change that,

it is so much bigger and samples such

at a larger volume of space

that it will have 10 million
new things every night

that it looks at the sky,

that's 10 million every
night for 10 years.

And so, suddenly, it's a whole
different ball game, right?

The scale is well-beyond anything

that has ever happened
in Time Domain Astronomy,

it opens up space that
we've never explored before.

To make sense of the deluge of data,

this project will make extensive use

of supercomputer models
designed to simulate

periods in cosmic history.

These powerful programs
are based on theories

of star and galaxy formation,

the influence of dark
matter and dark energy

and a host of other parameters.

Scientists will use them to test theories

about what drives cosmic evolution

by comparing simulation results

with data captured by the telescope.

- These data sets are so complex

that we really need
simulations of cosmic evolution

to even understand and analyze the data,

let alone, interpret them.

The computations really
translate our theories

of dark energy, dark matter,

cosmic evolution, into

observables that we can then go out

and test with our observations.

The LSST project will build upon

previous large-scale cosmic surveys.

The Sloan Digital Sky Survey

has mapped galaxies up to 1/3 the distance

to our visible horizon.

Astronomers are now leaping beyond that

with a project based on a summit

across the canyon from LSST.

It's called the Dark Energy Survey.

Here, at a dedicated four-meter telescope,

Felipe Menanteau and colleagues,

are pioneering new systems and procedures

for mining the light of deep space.

- Five, one, five, four, seven, three.

- Five, one, five,

four, seven, three?
- Yeah.

Because of the time it takes

for the light of distant
objects to reach us,

when these astronomers
look deep into the cosmos,

they are looking back in time.

- We are looking back in time,

kinda like an archeologist,

like digging deeper into the ground,

and at each one of these air pockets,

we are kinda like seeing

the relic, the fossils that were left.

So we cannot follow a galaxy back in time

but we can actually take a snapshots

of populations at different cosmic times

and see how they have been changing

since early on until today.

Yeah, but the thing is that,

you know, under this, there are.

20 trophy, no?

- No, no, you're not that,

you know, you're like 2016 A.

The telescope captures

the light of stars and galaxies

across the electromagnetic spectrum

from high energy ultraviolet

to low energy infrared.

These colors reveal important
galaxy characteristics

such as the rate of star birth,

the amount of dust or gas within them,

their distance from Earth.

The camera sensor
divides the field of view

into 62 high resolution detectors.

Each one captures countless
thousands of celestial objects

some bright and well-known,

others too subtle to
see with your eye

Night after night, month after month

the exposures pile up
across a survey area

that covers 1/4 of the southern sky,

or 1/8 of the entire
sky as seen from Earth.

With data from the Dark Energy Survey

combined with a much larger LSST survey

scientists will create a
three-dimensional map of galaxies

going back to when the universe
was half its current age.

- We only understood that
we live in a universe

full of galaxies in 1930s,

before that, we didn't understand

that we're placed in the universe,

and since then, there's
been this constant quest

to understand why galaxies
look the way they look,

how did they form,

and how this process had
been shaping also, you know,

the planets, the stars,
everything that is in there,

because you know,

galaxies are the building
blocks of the universe.

In recent years,

advanced telescopes have shown

that the universe is filled with galaxies

in a wide variety of shapes and sizes.

From giant spheres of ancient dying stars,

to complex twisted shapes

often run through with rings of dust,

the historic Hubble
Deep Field took us back

for the first time to the early
stages of galaxy formation.

It found that blurry
scraps of stars and gas,

visible at the dark margins of space,

are primitive galaxies.

Theory says they will one day merge

into larger mature galaxies.

- Something that, you know,

astronomy has been trying
to answer for decades,

particularly after the Hubble
Space Telescope was in space

and we were able to see
with amazing precision

the morphology and the shapes

of the earliest galaxies in the universe,

we've been trying to answer
and trying to connect

morphology and colors

with the evolutionary
stage of the galaxies.

- Okay, you have this kind of galaxy

and that kind of galaxy,

how do they fit together,
or do they fit together?

Does that galaxy turn into this galaxy?

Or the other way around?

Does this kind of galaxy never
become that kind of galaxy

because it didn't have
the right nurturing

or the right environment?

You know, if you were an alien coming

down with no knowledge of
how humans work

and you landed in a city

and you were just walking around

looking at some city blocks,

you would see all kinds
of different people.

You'd see babies and
you'd see old people

and you'd see, you know, teenagers

and people in their mid-20s,

but you wouldn't necessarily have an idea

of how all those people fit together.

Do people just arrive at
these different stages,

or are they working through
some evolutionary process?

So, it's the science of
what you understand that

things are evolving
so you'll have a baby

that then grows to a toddler,

that grows to a teenager that

eventually becomes an old person.

- Using the ALMA
Telescope Array in Chile,

astronomers caught a
glimpse of galaxy evolution

in its earliest stages.

They focused the telescope on

the southern constellation of Cetus

setting their sights on
a seemingly empty region.

Deep within it, about 3.5
billion light-years from Earth,

lies the galaxy cluster Abell 2744.

It's known as Pandora's Cluster

for the tangle of shapes created

when at least four smaller
galaxy clusters merge together.

To one side, astronomers
found a faint ghostly shape

that had been magnified by
dark matter within the cluster.

It is a pocket of stars

far beyond and much older
than the galaxy cluster.

The stars were being
born when the universe

was just 600 million years old.

This animation recreates
the ancient star cluster

surrounded by gas and
punctuated with supernovae.

Over time, most star
clusters like this

would've merged with a galaxy.

As it turns out,

a small number have managed
to stay intact

over the billions of years
since they were born.

In the bottom of that.

Finding them

within their original dark
matter cocoons

has become a passion for these members

of the Dark Energy Survey,

Alex Drlica-Wagner and Keith Bechtol.

So we don't forget

There are expectations from this model

of galaxy formation for

the existence of many of
these small dark matter clumps

in the halo of the Milky Way

and so, while this was an
expectation that was put forth,

basically from simulations,

they were very firm predictions about

if this paradigm were correct,

how many dwarf galaxies DES should find.

Astronomers have long known

that the Milky Way galaxy is enveloped

in a diffused halo of stars,

including some 160 large star clusters.

M15 is one of the densest known.

Gravitational interactions among its stars

have caused them to pack in tightly.

So-called globular clusters like this

are like pottery shards
found by archeologists

at the sites of ancient villages.

One, called Terzan 5,

has even managed to survive
a fall into our Milky Way.

It contains a population of
relatively metal poor stars

that would've been born
12 billion years ago.

There should be many
more clusters like these

in a wide variety of sizes

that have simply not had
time to enter the disk.

Where are they today?

When the first round of data

from the Dark Energy
Survey was released,

Alex and Keith began combing it

for light that could be resolved as stars.

They saw what they were looking for.

Tiny remnants of the Milky Way's birth,

star clusters almost entirely
devoid of metal content.

These dwarf galaxies turned
out to be dark matter rich

with about 10 times the ratio
of dark to visible matter

as seen in the galaxy as a whole.

- We have this idea that galaxies
form from the bottom, up,

you know, many, many
small galaxies, and then,

over billion of years,

they merge together to
form larger galaxies.

What this means is that
the smallest galaxies

were also the first
galaxies, and therefore,

they're the oldest,

and when you actually look
at these dwarf galaxies

and you study the
properties of their stars,

you find that the stars
are very, very old,

then most of them formed
over 10 billion years ago.

This realization is central

to cosmology's quest to
link the early stages

in growth of galaxies to cosmic

evolution on the largest scales.

That quest points to the
ingredients of matter and energy

that produce the very first
stars at the Cosmic Dawn.

Immediately after the Big Bang,

the universe was in a hut

and very, very, very homogenous,

but it wasn't perfectly homogenous.

In fact,

astronomers have found a tell-tale pattern

in light emitted when the universe

was just 300,000 years old,

the so-called cosmic microwave background.

In this image from the
European Planck satellite,

the colors indicate hot and cold patches

produced by tiny variations
in the energy of the Big Bang.

- These small fluctuations,

these small variations of matter,

then got amplified by gravity,

and these tiny variations,

this tiny clumping of matter,

were the seeds of the
galaxies that we see today,

and this is crucial.

The amount of variation that
we saw earlier in the universe

predicts together with all
of the other ingredients

that we need for a universe, predict

the rate in which the
structures are growing,

meaning decide the number
of clusters of galaxy,

the number of superclusters,

the shapes of the cosmic wave

is determined by that initial imprint.

To trace the
evolution of this imprint,

scientists are using a supercomputer model

to recreate the eruption
of stars and galaxies

in the Cosmic Dawn.

It begins in the darkness
of the early universe,

barely 6 million years after the Big Bang.

Gravity draws dark matter
into diffused halos.

Within them, hydrogen gas forms clouds

that become more and more dense over time.

As gravity compresses the clouds,

they begin to heat up,

then finally ignite to form
the first generation of stars.

These stars are giants,

much larger than any today.

One blows up in a powerful supernova.

The model shows an environment
transformed by the explosion.

The supernova litters its surroundings

with heavier elements
created in nuclear fusion.

Carbon, silicon,

iron, and more.

These so-called metals

cause surrounding clouds
of hydrogen to cool.

That allows them to collapse.

Turbulence breaks them
into smaller pockets,

a cluster of smaller
second generation stars,

now begins to form.

Here's a wider view of the scene

almost 400 million years later.

From data generated by the simulation,

scientists are working to isolate

the dynamics of galaxy evolution.

Stars are being born
where filaments of gas,

shown in blue, come together.

Ultraviolet light from these stars

begins to strip electrons
from hydrogen atoms

in a process called ionization.

That causes surrounding regions
to glow with visible light.

The ionized gas appears as bubbles.

They are associated with pockets
of elevated temperatures,

shown in red,

as well as high concentrations of metal

spread by supernovae, shown in green.

The simulation reveals a dynamic

that shape the course of cosmic history.

Heating from ionization

tends to push the gas out.

That suppresses the rate of star birth.

Metals, on the other hand,

allow pockets of gas to
cool and fall inward.

That increases the rate of star birth.

So, instead of stars forming

and collapsing immediately into galaxies

the universe becomes a wide mix

of hot and cold regions,

large and small star clusters,

and pockets of gas amid
clouds of dust rich in metals.

The small dwarf galaxies that astronomers

have spotted hovering above the Milky Way

are relics of this early period

and of the galaxy's early years.

- The formation of the
first generation of stars,

also referred to as Population III stars,

were these very massive stars
to form early in the universe,

polluting the intergalactic medium

and the interstellar medium with unique

chemical fingerprints
of their own formation,

different than the sorts of
supernovae that we see today.

And ultra faint dwarf
galaxies, we have evidence,

that many of them are actually

fossils of this era of reionization

where some of them are
thought to have form

before reionization took place.

And we also have evidence

from the chemical abundances of stars

and the ultra faint dwarf galaxies

that the chemicals that
they were enriched with

may have been coming from

that first generation of stars itself.

The supercomputer model

gives us a view of cosmic evolution

advancing to an age of
about a billion years.

The scene is dominated by star birth

and by star clusters merging

together into larger formations.

The universe continues to put
the brakes on galaxy growth.

While star birth spreads heat,

stifling the flow of gas into galaxies,

metals from stars and supernovae

have a cooling effect
that enables this flow.

Many of these early generation galaxies

join in larger aggregations.

Take the Spiderweb Galaxy,

10.6 billion light-years away.

A close examination shows that it sits

in the middle of a cluster
of galaxy fragments.

This animated reconstruction
shows the chaotic scene,

hundreds of small galaxies
and patches of stars

are interacting while drawing in

matter from the surrounding region.

Starting in the early
years of the Cosmic Dawn,

this simulation shows
a slice of the universe

in a region 350 million
light-years across.

The gravity of dark matter

gradually concentrated visible
matter into galaxy clusters.

At the centers of large galaxies,

black holes grew to super
massive proportions.

As matter flowed in,

they generated immense
expanding bubbles of gas.

These bubbles push beyond their galaxies

spreading waves of hot gas.

The heating from these bubbles

would slow the flow of
gas into the clusters.

That allowed smaller galaxies, like ours,

to form on the margins.

At the same time,

black hole winds seeded
the wider universe

with dust and metals
generated by supernovae.

Flash-forward to the present era.

Our galaxy has, by no means,
completed its evolution.

This simulation recreates the last

60 million years of its history.

Within the disk,

each flash of light is a supernova.

As time goes by,

thousands upon thousands
of these explosions

feed the galaxy with metals,

the cosmic dust from which
new generation of stars

and solar systems are born.

Though most of the Milky Way stars

reside within the disk,

some orbit far above or below it

in the galaxy's halo
and occasionally

pass through the disk.

Our galaxy today is the
product of countless

small and large mergers going all

the way back to the early universe.

Its landscapes are the
ever-evolving product

of star birth and star death.

The Milky Way is filled
with some 200 billion stars

born at each stage in
the life of the cosmos.

They are intermixed with
clouds of dust and gas,

all swirling around a bright

central region called the bulge.

We glimpse its origins
within a halo of stars

and small clusters, some
nearly as old as the universe.

From our vantage on Earth,

the universe continues to
reinvent itself

Okay.

See, we almost have star facts.

Okay, okay.

A supernova's life has
just reached Earth

from a nearby galaxy called Centaurus A.

Right now, it's taking an exposure, so.

Okay, yeah,
yeah, let's finish that one.

It's a particular
interest to the astronomers.

Its interaction with
surrounding dust clouds

can reveal the environment in which

its parent star lived and died.

- If you're a physicist,
you know, you have a lab,

and in your lab, you can
change the parameters

of your experiment and keep testing it.

When you are on an astronomer,

you cannot create stars.

You cannot create galaxies.

The universe is your lab

and you are a humble collector of light.

- I have five, one,
five, four, seven, three.

- Five, one, five, four, seven, three?

- Yeah.
- Okay.

Day by day, month by month,

the light of the universe
rolls into the data pipeline.

Here is one slice of the southern sky

from the Dark Energy Survey

extending roughly half the distance

to the edge of our visible horizon.

It's just the beginning
of a grand cosmic census

that includes galaxy clusters,

galaxy types, rates of star birth,

chemical abundances,

distances from Earth, and more.

When the data from this

and the Large Synoptic Survey are combined

and laid out in time,

they promise a record of
how the universe evolved

since its early moments.

- It is just jaw-dropping
to me that humans can even

undertake these big questions

and figure out where
we are in the universe,

and as we see the universe
changing with time,

over the last 13.7 billion years,

it gives us a sense of the
cosmic structure formation events

that have ultimately led to systems

like the sun being formed.

Discovering the shapes

and contours of the universe

is only the first step in
understanding how it came to be.

Astronomers will sift the data for clues

to the initial conditions that

came together in the Cosmic Dawn.

They'll test theories about the identity

of dark matter and dark energy.

- But there is also even this
more fundamental question,

which is, do these things even exist?

I think the evidence for
dark matter is quite strong,

we see it really explains a
number of different phenomenon.

Dark energy, I think, is
our best current hypothesis

for what is causing the
universe to speed up,

but it's,

it's still on, I would say, shaky ground.

Is dark energy just the
energy of empty space,

or is it the energy
associated with some new

fundamental particle of the universe?

Assuming
current observations hold up,

astronomers in the distant future

may produce a very different cosmic map,

one that reflects a universe pushed

further apart by dark energy.

Many of the galaxies we see today

will have receded beyond our horizons,

becoming invisible from Earth.

Our own Milky Way will remain intact,

still enveloped in the dark
matter that spawned it.

Its halo will become increasingly entwined

with that of the Andromeda
Galaxy, our larger neighbor.

It is now moving toward us

at about 400,000 kilometers per hour.

When the two meet,

several billion years from now,

their interaction will
dominate our night skies

from a point of view unique to their time,

those future astronomers will look out

at the horizon and ask,

how did it all come to be?

Where does it end?

We ask the same questions today

based on our point of view at
this moment in cosmic history.

Our technologies are allowing us

to see nearly to the beginning of time

and to tract the behavior of
the universe

on the largest of scales.

And yet,

the more we see,

the deeper the mysteries become.