Original subtitles

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.