Seeing the Beginning of Time (2017) Movie Script
- [Narrator] 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.
(ambient music)
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.
- [Felipe] Hey, hi, guys.
- [Man] Hey.
- [Narrator] They are mapping
the positions of galaxies
across the sky and extending
deep into the universe.
- [Felipe] So, that was
only at the end, can you.
- [Narrator] 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?
(eerie piano music)
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.
(eerie piano music)
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.
(eerie piano music)
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.
(ambient music)
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.
(upbeat music)
- 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.
- [Narrator] 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.
(uplifting piano music)
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.
(rumbling explosion)
Because Type Ia supernovae are all thought
to blow up in the same way,
they have the same intrinsic brightness.
(rumbling explosion)
That makes them ideal for
measuring cosmic distances.
(ambient music)
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.
(rumbling explosion)
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.
(ambient music)
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.
(eerie piano music)
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.
(eerie piano music)
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.
(eerie piano music)
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.
(moves into uplifting piano music)
At its heart, the LSST will be outfitted
with the largest digital
camera ever built.
- [Man] I don't see any leaks.
- [Narrator] That includes
the largest lens ever built,
now undergoing final
polish before assembly.
- Looks good, huh?
- Yeah.
- [Narrator] 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.
- [Narrator] 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.
- [Narrator] 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.
- [Narrator] The LSSproject 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.
(ambient music)
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.
- [Narrator] 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.
- [Felipe] Yeah, but the thing is that,
you know, under this, there are.
- [Woman] 20 trophy, no?
- No, no, you're not that,
you know, you're like 2016 A.
- [Narrator] The telescope captures
the light of stars and galaxies
across the electromagnetic spectrum
from high energy ultraviolet
to low energy infrared.
(ambient music)
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.
(suspenseful ambient music)
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.
- [Narrator] In recent years,
advanced telescopes have shown
that the universe is filled with galaxies
in a wide variety of shapes and sizes.
(ambient music)
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, you know,
eventually becomes an old person.
- [Narrator] 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.
(sinister ambient music)
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.
(upbeat dramatic music)
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.
- [Man] In the bottom of that.
- [Narrator] 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.
- [Man] So we don't forget (giggles).
- 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.
- [Narrator] 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.
(mysterious music)
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.
- [Narrator] 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.
(intense rumbling)
(mysterious piano music)
- Immediately after the Big Bang,
the universe was in a hut
and very, very, very homogenous,
but it wasn't perfectly homogenous.
(intense rumbling)
- [Narrator] 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.
- [Narrator] 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.
(ambient music)
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.
(moves into suspenseful piano music)
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.
(suspenseful piano music)
Turbulence breaks them
into smaller pockets,
a cluster of smaller
second generation stars,
now begins to form.
(suspenseful piano music)
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.
(mysterious piano music)
Stars are being born
where filaments of gas,
shown in blue, come together.
(mysterious piano music)
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.
- [Narrator] 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.
(dramatic music)
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.
(dramatic piano music)
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.
(dramatic piano music)
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.
(ambient music)
Our galaxy today is the
product of countless
small and large mergers going all
the way back to the early universe.
(ambient music)
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.
(ambient music)
From our vantage on Earth,
the universe continues to reinvent itself.
- [Felipe] Okay.
See, we almost have star facts.
- [Man] Okay, okay.
- [Narrator] A supernova's
life has just reached Earth
from a nearby galaxy called Centaurus A.
- [Man] Right now, it's
taking an exposure, so.
- [Felipe] Okay, yeah,
yeah, let's finish that one.
- [Narrator] 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.
- [Narrator] Day by day, month by month,
the light of the universe
rolls into the data pipeline.
(mysterious ambient music)
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.
- [Narrator] 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.
(sinister ambient music)
- 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?
- [Narrator] 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.
(sinister ambient music)
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.
(mysterious piano music)
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.
(ambient music)
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.
- [Felipe] Hey, hi, guys.
- [Man] Hey.
- [Narrator] They are mapping
the positions of galaxies
across the sky and extending
deep into the universe.
- [Felipe] So, that was
only at the end, can you.
- [Narrator] 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?
(eerie piano music)
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.
(eerie piano music)
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.
(eerie piano music)
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.
(ambient music)
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.
(upbeat music)
- 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.
- [Narrator] 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.
(uplifting piano music)
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.
(rumbling explosion)
Because Type Ia supernovae are all thought
to blow up in the same way,
they have the same intrinsic brightness.
(rumbling explosion)
That makes them ideal for
measuring cosmic distances.
(ambient music)
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.
(rumbling explosion)
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.
(ambient music)
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.
(eerie piano music)
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.
(eerie piano music)
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.
(eerie piano music)
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.
(moves into uplifting piano music)
At its heart, the LSST will be outfitted
with the largest digital
camera ever built.
- [Man] I don't see any leaks.
- [Narrator] That includes
the largest lens ever built,
now undergoing final
polish before assembly.
- Looks good, huh?
- Yeah.
- [Narrator] 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.
- [Narrator] 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.
- [Narrator] 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.
- [Narrator] The LSSproject 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.
(ambient music)
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.
- [Narrator] 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.
- [Felipe] Yeah, but the thing is that,
you know, under this, there are.
- [Woman] 20 trophy, no?
- No, no, you're not that,
you know, you're like 2016 A.
- [Narrator] The telescope captures
the light of stars and galaxies
across the electromagnetic spectrum
from high energy ultraviolet
to low energy infrared.
(ambient music)
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.
(suspenseful ambient music)
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.
- [Narrator] In recent years,
advanced telescopes have shown
that the universe is filled with galaxies
in a wide variety of shapes and sizes.
(ambient music)
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, you know,
eventually becomes an old person.
- [Narrator] 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.
(sinister ambient music)
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.
(upbeat dramatic music)
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.
- [Man] In the bottom of that.
- [Narrator] 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.
- [Man] So we don't forget (giggles).
- 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.
- [Narrator] 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.
(mysterious music)
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.
- [Narrator] 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.
(intense rumbling)
(mysterious piano music)
- Immediately after the Big Bang,
the universe was in a hut
and very, very, very homogenous,
but it wasn't perfectly homogenous.
(intense rumbling)
- [Narrator] 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.
- [Narrator] 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.
(ambient music)
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.
(moves into suspenseful piano music)
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.
(suspenseful piano music)
Turbulence breaks them
into smaller pockets,
a cluster of smaller
second generation stars,
now begins to form.
(suspenseful piano music)
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.
(mysterious piano music)
Stars are being born
where filaments of gas,
shown in blue, come together.
(mysterious piano music)
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.
- [Narrator] 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.
(dramatic music)
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.
(dramatic piano music)
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.
(dramatic piano music)
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.
(ambient music)
Our galaxy today is the
product of countless
small and large mergers going all
the way back to the early universe.
(ambient music)
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.
(ambient music)
From our vantage on Earth,
the universe continues to reinvent itself.
- [Felipe] Okay.
See, we almost have star facts.
- [Man] Okay, okay.
- [Narrator] A supernova's
life has just reached Earth
from a nearby galaxy called Centaurus A.
- [Man] Right now, it's
taking an exposure, so.
- [Felipe] Okay, yeah,
yeah, let's finish that one.
- [Narrator] 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.
- [Narrator] Day by day, month by month,
the light of the universe
rolls into the data pipeline.
(mysterious ambient music)
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.
- [Narrator] 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.
(sinister ambient music)
- 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?
- [Narrator] 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.
(sinister ambient music)
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.
(mysterious piano music)