Space's Deepest Secrets (2016–…): Season 1, Episode 7 - Attack of the Space Junk - full transcript
narrator: in the beginning,
the universe...
was a bit of a letdown,
really.
abel: for millions of years
after the big bang,
things were actually
rather boring.
it's just this soup.
loeb: the big bang was not
the moment of creation.
narrator:
the real moment of creation
came 100 million years later.
there was this magical, if you
like, metaphysical moment.
narrator: the cosmic dawn.
bromm:
the moment of first light.
narrator:
it wasn't really our univers
until the first star was born.
tingay:
the first stars are
fundamental to how
abel: they're like
the rock stars in the
universe.
they live fast and die young.
narrator: the first star
lit up the universe...
bromm: for the first time
in cosmic history,
the universe really is
getting interesting.
narrator: ...and began forging
the ingredients
that made you, me,
and everything around us.
loeb:
it was the starting point
that led to
the appearance of life.
narrator: astronomers
are now trying to witness
and understand
this moment of creation.
dunlop: i guess what we're
trying to achieve is
see the beginning of things.
loeb: we are dealing
with a scientific version
of the story of genesis.
"let there be light."
captions paid for by
discovery communications
narrator:
our story started with a hot,
...the big bang, often
credited
as being the moment of
creation.
loeb: the big bang
arranged the initial
conditions
of the universe.
early on, the universe
was very bright.
the temperature of the
radiation
was very high,
much higher than we find at
the centers of stars nowadays.
but as the universe expanded,
it cooled off.
narrator:
and as it cooled,
the universe became darker
and darker.
the lights went out, and
our universe was nothing more
than a vast, black fog
of hydrogen.
welcome to the dark ages.
loeb: several million years
after the big bang,
the universe
was dark and boring,
filled with cold hydrogen
atoms
floating through space.
all the things we treasure
did not exist.
the big bang was not
the moment of creation.
narrator: the big bang
gets all the credit,
but in reality,
it merely set the stage.
it created space and time,
a brief flash of light,
and some hydrogen fog,
but nothing that you or i
would recognize
as our present-day universe.
but somehow the universe
transformed itself
from dark and boring
to a place filled with stars
and, eventually,
planets and life.
figuring out
the almost 14-billion year
history of our universe
is like researching
your ancestry,
when no ancestors
left any records,
and some relatives
are in hiding.
loeb:
our cosmic family book.
that's an image of the earth
from the moon,
a quite beautiful image.
this is our home.
and, of course, we would like
to trace our cosmic roots
all the way back
to where we started.
narrator:
we have some brilliant
pictures
of our universe as it is to
our solar system...
...our milky way galaxy...
and our galactic neighbors.
and if we go to
the very beginning of the
album,
we also have
one spectacular image.
where it all began.
narrator: this picture shows
the cosmic microwave
background
from a mere 400,000 years
after the big bang.
loeb: this is an image
of the infant universe,
and that image shows us
the conditions
in the very early universe.
narrator:
but after that image,
there is a gap,
a period of darkness and fog
--
the dark ages.
we don't have photos of those.
these are the missing pages
in our photo album.
"the universe --
the cosmic photo album."
yep, that's worth a blow-up.
[ laughs ]
i guess this is the famous
cosmic dark ages.
[ laughs, mutters ]
narrator: astronomers are
desperate to fill in the
blanks.
somewhere in these
missing pages,
the first star was born...
[ both laughing ]
still blank.
...a moment of transformation
when the dark fog gave way
to a universe of light...
these are the bits
that we want to fill in.
how dark is it?
narrator:
...the real moment of
creation,
when light and matter
came into being.
the first star probably formed
about here.
somewhere in these pages.
narrator:
astronomers around the world
are devising
a variety of ingenious methods
to capture an image of that
first light in the universe.
at the edinburgh
royal observatory,
jim dunlop and ross mclure
are tunneling deep into space
to see the true dawn
of the universe.
dunlop:
what we're trying to achieve
is see the begin
see when the first structures
in the universe formed,
first stars, first galaxies.
narrator: they have been using
the hubble space telescope
to take one of its most
important pictures ever.
they arranged
for the hubble space telescope
to spend almost 44 days taking
one very ambitious photograph.
we're looking at
an ordinary patch of sky.
in this case, a little bit
to the right of orion.
but it's a tiny, tiny area
smaller than my fingernail
that looks blank
to the human eye.
narrator: it may look blank
with the naked eye,
but hubble is allowing
jim and ross
to tunnel deeper
into the distant universe
than ever before.
dunlop: we're trying
to look back as far as we can
to the beginning of time,
as close to the big bang
as we can manage.
here, we have orion,
a constellation
that many people will
recognize.
and we're zooming in,
tunneling in.
narrator:
to tunnel through space a
from the most distant objects
in the university,
they used what may be
the longest exposure
in cosmic history.
during the course of 650
orbits,
they pointed hubble
at the same tiny thumbnail
patch
of dark sky for 100 hours.
dunlop: we go deeper,
tunneling into deep space,
and we start to see
very faint galaxies appear.
narrator: as they tunnel,
they are reaching further
and further back in time,
because the further away
something is,
the longer its light
has taken to reach us.
and what we see
of a distant object
is how it looked
in the distant past.
one of the simplest ways
to look at is to realize
that even the sun is seen
as it was eight minutes ago.
so, if the sun disappeared,
we wouldn't know
for eight minutes.
and if jupiter disappeared,
we wouldn't know
for about an hour,
or something like that.
what's really staggering
is that once you get
to the nearest galaxy,
that delay is already
several million years.
narrator: which means that
we are seeing these galaxies
as they were
millions of years in the past.
deeper down the tunnel,
there are galaxies
that we see as they were
many billions of years ago.
dunlop: and here, we start
to come into this image
of what's called
the hubble ultra-deep field.
and these galaxies now,
we're seeing back
to within a billion years or
so
of the big bang.
dunlop: so, this here
is the deepest ever image
of the night sky ever taken.
narrator: the hubble
telescope's
deepest, most distant image,
shows us galaxies as they were
over 13 billion years ago.
that tiny, if you like, bore
hole that we made into the
sky.
so, it is a window
into a very different time.
mclure: we're the first people
to look at this data.
there's just one object
in there
from the thousands
that are in that image
that we identified
as being potentially the most
--
the most distant object
ever been seen by anyone.
this one here is the most
distant of all.
sort of zoomed in, it's just
literally a faint blob.
and there's only
a few photons of light
being collected
to see this object,
which we're seeing
only 500 million years
after the big bang.
narrator: this faint blob
turned
out to be an entire galaxy.
dunlop: see, it's not a star.
it's not point-like.
you can see
it's slightly extended,
which proves it's a galaxy.
and about 20 times smaller
than our milky way.
but that's about all we have
on this galaxy.
we can't even measure
its color very well.
it's only just
detected by hubble
in its very reddest
wavelength.
there's a certain excitement
to being the first person
to ever look at that image,
and from that image,
see this object
that nobody's ever seen
before.
let's put it
in the right place.
narrator:
ross and jim have identified
it's more than
13 billion years old.
you can do the sticking.
why not?
this image shows
one of the first galaxies,
billions of stars
gathered together.
which way up is it?
but the first individual star
is not in this galaxy.
we will need other tools
to see that.
at siding spring observatory
in australia,
stefan keller is trying to see
the very first star
to ever light up the universe.
he's not staring at
the furthest reaches of space.
he's looking
much closer to home.
the star we're most familiar
with is, of course, our own
sun.
keller: here we are
on top of the mountains
catching the last rays
of the sun.
and the sun
is very special for us,
but it's a very average
sort of star.
it's been around
for about 4.6 billion years --
1/3 of the lifetime
of the universe.
narrator:
that may sound like a long
time,
but it's pretty typical
for stars in our galaxy.
keller: what we're looking for
are those very rare stars
that are amongst the oldest
stars that are out there.
narrator: stars can be
100,000 times bigger than
earth,
but all stefan has
available for study
is a pinprick of light.
keller: light is all
that we have to work with.
we need special ways
of dissecting the starlight
that is coming to us
so that we can understand
where they've come from,
how old they are.
when we decode that,
we can uniquely identify
some of the oldest stars
that remain with us today.
narrator:
by analyzing starlight,
stefan can see
what the star is made of.
and if he knows that,
he can estimate the star's
age.
keller:
stars are fundamental to life,
that have created everything
that we need on earth.
the rocks that we see have
been
formed inside a stellar
interior
and then thrown back
out into the universe.
the gold and the silver
in the rings on my finger,
they've all been made
in a supernova.
there's no other place
in the universe
that you can create elements
like that.
narrator:
after a lifetime forging
a star will eventually
run out of fuel.
many then explode
in a massive supernova,
spewing out a cloud of debris
into interstellar space.
this rich cloud is then
recycled
into the next generation
of stars.
keller:
again and again and again,
this cosmic recycling
has taken place.
in a star like the sun,
there have been about 1,000
generations of stars before
it.
narrator: each generation has
a richer and richer
composition
of heavier and heavier
elements,
and particularly noticeable
is the buildup of iron.
keller: so, the amount of iron
is an arrow of time.
it shows us how old the star
is.
narrator: if you want to find
a very old star,
you need to find one
with very little iron.
the way to do that
is to look for a specific
but minute variation in color.
each night, stefan's robotic
skymapper telescope
captures the light
from nearly a million stars.
it automatically analyzes
the color of each one
and arranges them
on a graph for stefan
according to iron content.
so, we see most stars like the
sun have quite a lot of iron.
but then there's
this tail of objects
that don't have
much iron in them at all.
and they're the potential
needles in the haystack.
narrator: in 2013, skymapper
presented stefan with a star
that stood apart from all
others
on stefan's graph.
here you see about 100 or so
ordinary stars
scattered around the field,
and in the center
is the star that we
discovered.
narrator: this star had
incredibly low iron content.
at first, we thought we
must've
done something wrong here.
but we confirmed it
the next night.
and that's when things
really got exciting.
narrator: the next step
was to take a much closer look
with a much bigger telescope.
keller:
we were lucky enough
to find some telescope time
over in chile,
and we stared at this one star
the entire night,
building up a very detailed
spectrum of the star.
there are a number of things
that we saw
that we just hadn't
ever seen before.
what we see here
is a spectrum of light
from a star
that's similar to the sun.
this is like a fingerprint
from the star,
and it tells us how much iron,
magnesium, and calcium
is inside that star.
and you can see that there's
quite a lot of lines here.
in the case of our star,
which is at the top here,
all we see
are the lines of hydrogen,
and a little bit here,
which is carbon.
and, so, it's quite
a different recipe.
and, indeed, we just don't see
any iron detectable
in this star.
and we knew that we were
onto something very exciting,
'cause we had never seen
a star like this before.
narrator:
a star with no detectable iron
must've been made very early
in the process
of cosmic recycling.
it's been around
for 13.6 billion years.
it's a very pristine star.
it formed very early on
in the history of the universe
before much stellar recycling
had taken place.
narrator: stefan had
discovered
the oldest star ever seen.
it's been burning
for 13.6 billion years --
not quite the first star,
but almost.
in fact, what we're able to do
with this star
is, for the first time, say
that there was only one star
that preceded it.
narrator:
stefan's star had to have been
formed from the exploding d
of one of the very first stars
in the universe.
stefan's image
of a second-generation star
takes us closer to the dark
ages
than ever before.
ah. here we are.
that looks like the right
spot.
this is a star that predates
the milky way galaxy itself.
narrator:
but we must go even further,
because even before this
came the very first generation
of stars of the cosmic dawn.
the first stars came together
in a dark sea of hydrogen
atoms.
bromm: as you go back
to this time of the dark ages,
the universe looked
completely different.
if you had a human observer
translated back in time,
you would see a completely
dark,
boring, featureless universe
--
an utterly alien place,
it would appear to us.
it was a universe
without any light.
there were no stars,
no galaxies.
narrator: just a collection
of lone hydrogen atoms
and the odd bit of helium
spread out in a diffuse fog.
bromm: hydrogen would be
in its most primitive state --
single hydrogen atoms.
and, basically,
we would have, say,
a volume of the size
of my stretched-out arms.
then in this volume,
you would particularly have
one hydrogen atom.
narrator: so diffuse
that if a hydrogen atom
was the size
of a ping pong ball,
the next closest one
would be halfway to the moon.
bromm: so, we have
this very diffuse universe.
how do we get stars out of
this?
narrator:
volker bromm decided
the only way to get a picture
of the first star
was to build one from scratch,
one hydrogen atom at a time.
it was time
to forget the telescopes
and use a supercomputer.
narrator:
astronomer volker bromm
to create an image
of the first star ever formed.
bromm: we can input
into the supercomputers
all the laws of physics,
from, as we say,
first principle.
we can put in
the initial conditions,
because initial conditions
is what we see here.
there are no missing pieces.
we have all the laws of
physics
that describe the behavior
of these basic ingredients,
and at that point,
we set up the computer,
and then we let it go.
[ operatic singing ]
narrator: the scale of the
calculation seems impossible
--
to model the behavior
of vast clouds
of primordial hydrogen gas,
trillions of hydrogen atoms,
one interaction at a time,
and to ask the question,
"will they form a star?"
bromm: at first, you might
think
this is hopeless.
how do we get things like
stars
out of this?
but what really then kicks in
is the force of gravity.
the force of gravity
has an infinite reach.
it reaches over
far stretches of the universe,
millions of light-years.
so, the force of gravity, in
a way, is a very patient
force.
narrator: tiny fluctuations
left over from the big bang
meant some regions were ever
so
slightly more dense than
others,
allowing gravity
to work its magic.
bromm: gravity would very,
very slowly act
to clump matter together.
certain regions of space
where then the density
of primordial stuff
is larger than the rest.
and then what would happen is
millions of years,
million of years
would create and attract
more and more material.
narrator:
eventually, gravity would pull
such a vast collection of a
so incredibly close together
under such extreme pressure,
that it could trigger
nuclear fusion,
and a star could be born.
but even as gravity is pulling
the gas atoms closer together,
there's another force
trying to push them apart.
bromm:
and it comes together.
when we compress gas,
then it also is heated up.
and at some point, the heat --
we basically have random
motion.
and the random motion will
basically prevent gravity
from condensing the gas
any further.
narrator: the more
that gravity squeezes inwards,
the more the gas heats up
and pushes outwards.
it's a stalemate.
and then the important
question
is, "can this gas,
this primordial gas,
can this get rid of the heat?"
narrator: what tipped
the balance in favor of
gravity
were a few chance encounters
between hydrogen atoms.
bromm: very rarely, something
very dramatically happened.
you have the two hydrogen
atoms,
and they meet, and they form
hydrogen molecules.
narrator:
and, crucially, a pair like
this
are able to absorb
a tiny bit of heat
in a way that a lone atom
can't.
this is the key process
for the entire end
of the cosmic dark ages.
the gas can cool.
gravity can take over
and eventually create
conditions
that are so extreme in terms
of temperature and density
that you can trigger
nuclear fusion.
you can eventually form,
out of this material, stars.
[ operatic singing ]
narrator:
the first star is born.
the first light of the
universe
is created.
the gas has collapsed
for millions of years
into the center of the system,
and now, for the first time
in cosmic history,
we see the moment
of first light,
the moment
that the first star formed.
narrator:
after 100 million years,
this was how the dark ages
finally came to an end.
the first stars were giants --
100 times or more
the mass of the sun.
bromm:
that has dramatic
consequences,
because massive stars
have a very different life,
a much more violent life
than the kind of low-mass star
that the sun is.
they would be 20 times
hotter...
...shining ultraviolet blue...
...10 million times
more luminous than the sun.
narrator:
volker bromm's supercomputer
of the first stars ever to
shine
in the darkness of space.
bromm: the one picture
that really captures
this metaphysical moment
of first light
would be like this,
a supercomputer frame
that shows the very first
star.
narrator:
it's a realistic image
of the first light
from the first-ever star.
let's patch it in
just at the end
of the cosmic dark ages,
because this is
when it happened.
narrator:
it shows the moment when,
from the impenetrable fog
of the dark ages,
light finally dawned
on the universe.
loeb: soon after
the first star formed,
a few million years later,
another star formed
somewhere else.
and then the process
accelerated.
narrator: after 100 million
years of darkness,
lights were coming on
across the universe.
loeb:
it grew up exponentially.
very quickly, within tens
of millions of years,
there were plenty of stars
filling up the universe.
narrator:
this was the era that so many
astronomers have searched for
the cosmic dawn.
loeb: the cosmic dawn
would've been spectacular.
new galaxies were forming
out of darkness.
this age of enlightenment was
a very dynamic period of time.
narrator: these great furnaces
start forging
the more useful ingredients
of the universe.
abel: all of a sudden,
it gets interesting.
for the first time,
new elements are being made.
they take hydrogen,
turn it into helium.
helium gets combined
to make carbon,
and we go to oxygen, and so
on.
narrator: deep in their
hearts,
the first giant stars
began the transformation
of matter,
producing the heavy elements
necessary for life.
they were huge
but so hot that they burned
through their fuel quickly.
abel: they can only live
for a very short time --
only a few million years.
that's really nothing.
we often say they're like
the rock stars in the
universe.
they live fast and die young.
and so, by the time
you make another one,
over here, this one
may already be ready to die.
narrator:
when they died, they died in
a hypernova --
the biggest explosions
ever seen in the universe.
stars were appearing
and disappearing.
it's like fireworks.
it's very dynamic.
loeb:
these were the very first
events
that spewed out
the heavy elements
and led to the formation of
the second generation of
stars.
narrator: for the first time,
stars were made,
light was produced,
and heavy elements were
forged.
and yet, the dramatic events
of the cosmic dawn
were still shrouded
behind a veil of fog.
abel: those first stars --
very bright, you know?
they could be a million times
as bright as our own sun,
giving off tons and tons
of light.
but the light's not getting
very far yet.
actually, most of it
gets sort of stopped
by all this fog of hydrogen.
narrator:
atoms of neutral hydrogen
filled the space
between the giant first stars.
abel:
as the light leaves the
surface of the st
it gets stopped,
so it couldn't get to us yet.
so the universe at this point
is still opaque.
narrator: tom abel uses
supercomputer simulations
to model these first stars
and the fog
to see how the universe
became transparent.
abel: what we'd like to do
is try and predict the past.
what we have here is
one of the first stars
forming.
there's a whole filament of
gas.
that was all that hydrogen
gas.
now, see, everything that gets
blue here gets really hot.
that's the ultraviolet
radiation
from this star
affecting everything
up to thousands of light-years
away from that star.
the radiation that they give
off, as it's trying to escape,
ionizes hydrogen gas.
but as a consequence,
you actually make things
transparent.
radiation hits the fog.
fog gets transparent.
now my boundary to the fog
is further away.
radiation in the next little
bit
can go a little further.
so, i make these bubbles.
narrator:
each star created a clearing
blowing a bubble
of transparent space.
abel: the simplest way to
think
about it is some swiss cheese.
as their light travels out,
it changes the "cheese."
our air bubbles are growing,
and we make ever larger ones.
in this way
of thinking about it,
at the end, we end up
with no cheese at all.
[ laughs ]
all the bubbles are so big
that the light from those
objects really travel freely.
narrator:
this image shows the cosmic
as the first light clears a
path
through the universe.
abel:
we're not even complete yet.
some parts of the universe
are still neutral and opaque.
but there it goes.
the whole fog lifts,
and all the galaxies
are revealed.
re-ionization would be
complete
somewhere in these pages.
narrator: tom's models
offer an explanation
for how our universe
finally became transparent.
shall we glue it in?
maybe with a light glue.
[ laughs ]
in case we have to correct it.
narrator: the theories and
computer models are valid,
but there's still testing
to be done in the real world.
narrator:
steven tingay is trying to see
but he's doing it
in an unexpected way.
he's trying to tune in
to radio hydrogen.
[ rock music playing ]
first light tonight
first light tomorrow
first light this morning
tingay:
well, in the early universe,
there were vast amounts
of hydrogen,
and each one
of those hydrogen atoms
can randomly give off
a radio wave.
and, so, we can tune
our telescope
to that radio frequency,
and then we're tuning in
to the hydrogen gas.
first light this morning
first light this evening
first light tonight
been looking back
narrator:
unfortunately, the band of
radio where hyd
is already filled with music
and news here on earth.
first, i was an ancient
hydrogen gas
produces radio waves
at a very specific frequency.
that's similar
to sort of f.m. radio
by the time they get to us.
so, it means that we've got to
build our telescopes
in areas where
there's no human interference.
so, you can't have f.m. radio.
you can't have tv.
you can't have mobile phones,
traffic on the road,
or anything like that.
first light tonight
first light this evening
first light this morning
distance is the only cure,
so we need to be in the middle
of nowhere, basically.
narrator: murchison county,
western australia,
is bigger than massachusetts
and rhode island combined,
but with less than
150 residents.
then i found it
i did it finally, oh
it's a terrible place
if you want radio, television,
or cellphone service.
i prayed till it was gone
my all in light
but it's the perfect place
to hear radio
from the beginning of time.
this is steven's telescope,
the murchison widefield array,
or mwa.
tingay: so, what we've got
here
are the antennas.
we have a cluster
of 16 of them here.
so, you can build
a lot of antennas
and get a very
sensitive telescope.
narrator: 2,000 antennas
spread
out over 1/3 of a square mile
are sensitive enough
to receive radio waves
that have traveled more than
13 billion light-years.
tingay: so, that gas outside
the
bubble produces the radio
waves.
no radio waves from the
bubble.
and so, for us,
we're sort of looking
for this swiss-cheese pattern
of bubbles and holes
in the hydrogen gas
distribution.
narrator: although it's not
possible to see the first
stars,
it should be possible
with this radio telescope
to find clues about the way
they cleared the hydrogen fog.
tingay: we don't actually see
the stars themselves.
we see the effect of the star
on its environment.
this is an actual image
made from the mwa data.
this is a patch of the sky
that's around about
30 degrees across,
so it's quite a big
chunk of sky.
so, we're looking through
our atmosphere.
we're looking
through our galaxy.
we're looking through
most of the universe.
if you look carefully down
here,
you can see many, many specks,
and these are all
galaxies or quasars,
millions, billions
of light-years away.
so, we need to remove
each of these signals one by
one
in order to peel back
those layers.
and, hopefully,
what we're left with
is just the signature of the
gas
and the first stars forming
13 billion years ago.
narrator: this radio signal
will be our first direct
contact
with the very first stars
in the universe.
tingay:
it's incredible to think
that in this very image
that i'm looking at right now,
that signal exists.
what's really special for me
is being able to look at this
while sort of sitting
in an ancient landscape
where we've actually built the
telescope and collected the
data
from these signals
that have traversed
billions of light-years
throughout the universe.
so, it's just astonishing
on a number of different
levels
for me.
loeb: we are all curious
where we came from.
we are now at a special time
that allows us to explore
these questions
scientifically.
we are able to peer
deep into space
and see those very early
sources of light
that tell us
how we came into existence.
the universe...
was a bit of a letdown,
really.
abel: for millions of years
after the big bang,
things were actually
rather boring.
it's just this soup.
loeb: the big bang was not
the moment of creation.
narrator:
the real moment of creation
came 100 million years later.
there was this magical, if you
like, metaphysical moment.
narrator: the cosmic dawn.
bromm:
the moment of first light.
narrator:
it wasn't really our univers
until the first star was born.
tingay:
the first stars are
fundamental to how
abel: they're like
the rock stars in the
universe.
they live fast and die young.
narrator: the first star
lit up the universe...
bromm: for the first time
in cosmic history,
the universe really is
getting interesting.
narrator: ...and began forging
the ingredients
that made you, me,
and everything around us.
loeb:
it was the starting point
that led to
the appearance of life.
narrator: astronomers
are now trying to witness
and understand
this moment of creation.
dunlop: i guess what we're
trying to achieve is
see the beginning of things.
loeb: we are dealing
with a scientific version
of the story of genesis.
"let there be light."
captions paid for by
discovery communications
narrator:
our story started with a hot,
...the big bang, often
credited
as being the moment of
creation.
loeb: the big bang
arranged the initial
conditions
of the universe.
early on, the universe
was very bright.
the temperature of the
radiation
was very high,
much higher than we find at
the centers of stars nowadays.
but as the universe expanded,
it cooled off.
narrator:
and as it cooled,
the universe became darker
and darker.
the lights went out, and
our universe was nothing more
than a vast, black fog
of hydrogen.
welcome to the dark ages.
loeb: several million years
after the big bang,
the universe
was dark and boring,
filled with cold hydrogen
atoms
floating through space.
all the things we treasure
did not exist.
the big bang was not
the moment of creation.
narrator: the big bang
gets all the credit,
but in reality,
it merely set the stage.
it created space and time,
a brief flash of light,
and some hydrogen fog,
but nothing that you or i
would recognize
as our present-day universe.
but somehow the universe
transformed itself
from dark and boring
to a place filled with stars
and, eventually,
planets and life.
figuring out
the almost 14-billion year
history of our universe
is like researching
your ancestry,
when no ancestors
left any records,
and some relatives
are in hiding.
loeb:
our cosmic family book.
that's an image of the earth
from the moon,
a quite beautiful image.
this is our home.
and, of course, we would like
to trace our cosmic roots
all the way back
to where we started.
narrator:
we have some brilliant
pictures
of our universe as it is to
our solar system...
...our milky way galaxy...
and our galactic neighbors.
and if we go to
the very beginning of the
album,
we also have
one spectacular image.
where it all began.
narrator: this picture shows
the cosmic microwave
background
from a mere 400,000 years
after the big bang.
loeb: this is an image
of the infant universe,
and that image shows us
the conditions
in the very early universe.
narrator:
but after that image,
there is a gap,
a period of darkness and fog
--
the dark ages.
we don't have photos of those.
these are the missing pages
in our photo album.
"the universe --
the cosmic photo album."
yep, that's worth a blow-up.
[ laughs ]
i guess this is the famous
cosmic dark ages.
[ laughs, mutters ]
narrator: astronomers are
desperate to fill in the
blanks.
somewhere in these
missing pages,
the first star was born...
[ both laughing ]
still blank.
...a moment of transformation
when the dark fog gave way
to a universe of light...
these are the bits
that we want to fill in.
how dark is it?
narrator:
...the real moment of
creation,
when light and matter
came into being.
the first star probably formed
about here.
somewhere in these pages.
narrator:
astronomers around the world
are devising
a variety of ingenious methods
to capture an image of that
first light in the universe.
at the edinburgh
royal observatory,
jim dunlop and ross mclure
are tunneling deep into space
to see the true dawn
of the universe.
dunlop:
what we're trying to achieve
is see the begin
see when the first structures
in the universe formed,
first stars, first galaxies.
narrator: they have been using
the hubble space telescope
to take one of its most
important pictures ever.
they arranged
for the hubble space telescope
to spend almost 44 days taking
one very ambitious photograph.
we're looking at
an ordinary patch of sky.
in this case, a little bit
to the right of orion.
but it's a tiny, tiny area
smaller than my fingernail
that looks blank
to the human eye.
narrator: it may look blank
with the naked eye,
but hubble is allowing
jim and ross
to tunnel deeper
into the distant universe
than ever before.
dunlop: we're trying
to look back as far as we can
to the beginning of time,
as close to the big bang
as we can manage.
here, we have orion,
a constellation
that many people will
recognize.
and we're zooming in,
tunneling in.
narrator:
to tunnel through space a
from the most distant objects
in the university,
they used what may be
the longest exposure
in cosmic history.
during the course of 650
orbits,
they pointed hubble
at the same tiny thumbnail
patch
of dark sky for 100 hours.
dunlop: we go deeper,
tunneling into deep space,
and we start to see
very faint galaxies appear.
narrator: as they tunnel,
they are reaching further
and further back in time,
because the further away
something is,
the longer its light
has taken to reach us.
and what we see
of a distant object
is how it looked
in the distant past.
one of the simplest ways
to look at is to realize
that even the sun is seen
as it was eight minutes ago.
so, if the sun disappeared,
we wouldn't know
for eight minutes.
and if jupiter disappeared,
we wouldn't know
for about an hour,
or something like that.
what's really staggering
is that once you get
to the nearest galaxy,
that delay is already
several million years.
narrator: which means that
we are seeing these galaxies
as they were
millions of years in the past.
deeper down the tunnel,
there are galaxies
that we see as they were
many billions of years ago.
dunlop: and here, we start
to come into this image
of what's called
the hubble ultra-deep field.
and these galaxies now,
we're seeing back
to within a billion years or
so
of the big bang.
dunlop: so, this here
is the deepest ever image
of the night sky ever taken.
narrator: the hubble
telescope's
deepest, most distant image,
shows us galaxies as they were
over 13 billion years ago.
that tiny, if you like, bore
hole that we made into the
sky.
so, it is a window
into a very different time.
mclure: we're the first people
to look at this data.
there's just one object
in there
from the thousands
that are in that image
that we identified
as being potentially the most
--
the most distant object
ever been seen by anyone.
this one here is the most
distant of all.
sort of zoomed in, it's just
literally a faint blob.
and there's only
a few photons of light
being collected
to see this object,
which we're seeing
only 500 million years
after the big bang.
narrator: this faint blob
turned
out to be an entire galaxy.
dunlop: see, it's not a star.
it's not point-like.
you can see
it's slightly extended,
which proves it's a galaxy.
and about 20 times smaller
than our milky way.
but that's about all we have
on this galaxy.
we can't even measure
its color very well.
it's only just
detected by hubble
in its very reddest
wavelength.
there's a certain excitement
to being the first person
to ever look at that image,
and from that image,
see this object
that nobody's ever seen
before.
let's put it
in the right place.
narrator:
ross and jim have identified
it's more than
13 billion years old.
you can do the sticking.
why not?
this image shows
one of the first galaxies,
billions of stars
gathered together.
which way up is it?
but the first individual star
is not in this galaxy.
we will need other tools
to see that.
at siding spring observatory
in australia,
stefan keller is trying to see
the very first star
to ever light up the universe.
he's not staring at
the furthest reaches of space.
he's looking
much closer to home.
the star we're most familiar
with is, of course, our own
sun.
keller: here we are
on top of the mountains
catching the last rays
of the sun.
and the sun
is very special for us,
but it's a very average
sort of star.
it's been around
for about 4.6 billion years --
1/3 of the lifetime
of the universe.
narrator:
that may sound like a long
time,
but it's pretty typical
for stars in our galaxy.
keller: what we're looking for
are those very rare stars
that are amongst the oldest
stars that are out there.
narrator: stars can be
100,000 times bigger than
earth,
but all stefan has
available for study
is a pinprick of light.
keller: light is all
that we have to work with.
we need special ways
of dissecting the starlight
that is coming to us
so that we can understand
where they've come from,
how old they are.
when we decode that,
we can uniquely identify
some of the oldest stars
that remain with us today.
narrator:
by analyzing starlight,
stefan can see
what the star is made of.
and if he knows that,
he can estimate the star's
age.
keller:
stars are fundamental to life,
that have created everything
that we need on earth.
the rocks that we see have
been
formed inside a stellar
interior
and then thrown back
out into the universe.
the gold and the silver
in the rings on my finger,
they've all been made
in a supernova.
there's no other place
in the universe
that you can create elements
like that.
narrator:
after a lifetime forging
a star will eventually
run out of fuel.
many then explode
in a massive supernova,
spewing out a cloud of debris
into interstellar space.
this rich cloud is then
recycled
into the next generation
of stars.
keller:
again and again and again,
this cosmic recycling
has taken place.
in a star like the sun,
there have been about 1,000
generations of stars before
it.
narrator: each generation has
a richer and richer
composition
of heavier and heavier
elements,
and particularly noticeable
is the buildup of iron.
keller: so, the amount of iron
is an arrow of time.
it shows us how old the star
is.
narrator: if you want to find
a very old star,
you need to find one
with very little iron.
the way to do that
is to look for a specific
but minute variation in color.
each night, stefan's robotic
skymapper telescope
captures the light
from nearly a million stars.
it automatically analyzes
the color of each one
and arranges them
on a graph for stefan
according to iron content.
so, we see most stars like the
sun have quite a lot of iron.
but then there's
this tail of objects
that don't have
much iron in them at all.
and they're the potential
needles in the haystack.
narrator: in 2013, skymapper
presented stefan with a star
that stood apart from all
others
on stefan's graph.
here you see about 100 or so
ordinary stars
scattered around the field,
and in the center
is the star that we
discovered.
narrator: this star had
incredibly low iron content.
at first, we thought we
must've
done something wrong here.
but we confirmed it
the next night.
and that's when things
really got exciting.
narrator: the next step
was to take a much closer look
with a much bigger telescope.
keller:
we were lucky enough
to find some telescope time
over in chile,
and we stared at this one star
the entire night,
building up a very detailed
spectrum of the star.
there are a number of things
that we saw
that we just hadn't
ever seen before.
what we see here
is a spectrum of light
from a star
that's similar to the sun.
this is like a fingerprint
from the star,
and it tells us how much iron,
magnesium, and calcium
is inside that star.
and you can see that there's
quite a lot of lines here.
in the case of our star,
which is at the top here,
all we see
are the lines of hydrogen,
and a little bit here,
which is carbon.
and, so, it's quite
a different recipe.
and, indeed, we just don't see
any iron detectable
in this star.
and we knew that we were
onto something very exciting,
'cause we had never seen
a star like this before.
narrator:
a star with no detectable iron
must've been made very early
in the process
of cosmic recycling.
it's been around
for 13.6 billion years.
it's a very pristine star.
it formed very early on
in the history of the universe
before much stellar recycling
had taken place.
narrator: stefan had
discovered
the oldest star ever seen.
it's been burning
for 13.6 billion years --
not quite the first star,
but almost.
in fact, what we're able to do
with this star
is, for the first time, say
that there was only one star
that preceded it.
narrator:
stefan's star had to have been
formed from the exploding d
of one of the very first stars
in the universe.
stefan's image
of a second-generation star
takes us closer to the dark
ages
than ever before.
ah. here we are.
that looks like the right
spot.
this is a star that predates
the milky way galaxy itself.
narrator:
but we must go even further,
because even before this
came the very first generation
of stars of the cosmic dawn.
the first stars came together
in a dark sea of hydrogen
atoms.
bromm: as you go back
to this time of the dark ages,
the universe looked
completely different.
if you had a human observer
translated back in time,
you would see a completely
dark,
boring, featureless universe
--
an utterly alien place,
it would appear to us.
it was a universe
without any light.
there were no stars,
no galaxies.
narrator: just a collection
of lone hydrogen atoms
and the odd bit of helium
spread out in a diffuse fog.
bromm: hydrogen would be
in its most primitive state --
single hydrogen atoms.
and, basically,
we would have, say,
a volume of the size
of my stretched-out arms.
then in this volume,
you would particularly have
one hydrogen atom.
narrator: so diffuse
that if a hydrogen atom
was the size
of a ping pong ball,
the next closest one
would be halfway to the moon.
bromm: so, we have
this very diffuse universe.
how do we get stars out of
this?
narrator:
volker bromm decided
the only way to get a picture
of the first star
was to build one from scratch,
one hydrogen atom at a time.
it was time
to forget the telescopes
and use a supercomputer.
narrator:
astronomer volker bromm
to create an image
of the first star ever formed.
bromm: we can input
into the supercomputers
all the laws of physics,
from, as we say,
first principle.
we can put in
the initial conditions,
because initial conditions
is what we see here.
there are no missing pieces.
we have all the laws of
physics
that describe the behavior
of these basic ingredients,
and at that point,
we set up the computer,
and then we let it go.
[ operatic singing ]
narrator: the scale of the
calculation seems impossible
--
to model the behavior
of vast clouds
of primordial hydrogen gas,
trillions of hydrogen atoms,
one interaction at a time,
and to ask the question,
"will they form a star?"
bromm: at first, you might
think
this is hopeless.
how do we get things like
stars
out of this?
but what really then kicks in
is the force of gravity.
the force of gravity
has an infinite reach.
it reaches over
far stretches of the universe,
millions of light-years.
so, the force of gravity, in
a way, is a very patient
force.
narrator: tiny fluctuations
left over from the big bang
meant some regions were ever
so
slightly more dense than
others,
allowing gravity
to work its magic.
bromm: gravity would very,
very slowly act
to clump matter together.
certain regions of space
where then the density
of primordial stuff
is larger than the rest.
and then what would happen is
millions of years,
million of years
would create and attract
more and more material.
narrator:
eventually, gravity would pull
such a vast collection of a
so incredibly close together
under such extreme pressure,
that it could trigger
nuclear fusion,
and a star could be born.
but even as gravity is pulling
the gas atoms closer together,
there's another force
trying to push them apart.
bromm:
and it comes together.
when we compress gas,
then it also is heated up.
and at some point, the heat --
we basically have random
motion.
and the random motion will
basically prevent gravity
from condensing the gas
any further.
narrator: the more
that gravity squeezes inwards,
the more the gas heats up
and pushes outwards.
it's a stalemate.
and then the important
question
is, "can this gas,
this primordial gas,
can this get rid of the heat?"
narrator: what tipped
the balance in favor of
gravity
were a few chance encounters
between hydrogen atoms.
bromm: very rarely, something
very dramatically happened.
you have the two hydrogen
atoms,
and they meet, and they form
hydrogen molecules.
narrator:
and, crucially, a pair like
this
are able to absorb
a tiny bit of heat
in a way that a lone atom
can't.
this is the key process
for the entire end
of the cosmic dark ages.
the gas can cool.
gravity can take over
and eventually create
conditions
that are so extreme in terms
of temperature and density
that you can trigger
nuclear fusion.
you can eventually form,
out of this material, stars.
[ operatic singing ]
narrator:
the first star is born.
the first light of the
universe
is created.
the gas has collapsed
for millions of years
into the center of the system,
and now, for the first time
in cosmic history,
we see the moment
of first light,
the moment
that the first star formed.
narrator:
after 100 million years,
this was how the dark ages
finally came to an end.
the first stars were giants --
100 times or more
the mass of the sun.
bromm:
that has dramatic
consequences,
because massive stars
have a very different life,
a much more violent life
than the kind of low-mass star
that the sun is.
they would be 20 times
hotter...
...shining ultraviolet blue...
...10 million times
more luminous than the sun.
narrator:
volker bromm's supercomputer
of the first stars ever to
shine
in the darkness of space.
bromm: the one picture
that really captures
this metaphysical moment
of first light
would be like this,
a supercomputer frame
that shows the very first
star.
narrator:
it's a realistic image
of the first light
from the first-ever star.
let's patch it in
just at the end
of the cosmic dark ages,
because this is
when it happened.
narrator:
it shows the moment when,
from the impenetrable fog
of the dark ages,
light finally dawned
on the universe.
loeb: soon after
the first star formed,
a few million years later,
another star formed
somewhere else.
and then the process
accelerated.
narrator: after 100 million
years of darkness,
lights were coming on
across the universe.
loeb:
it grew up exponentially.
very quickly, within tens
of millions of years,
there were plenty of stars
filling up the universe.
narrator:
this was the era that so many
astronomers have searched for
the cosmic dawn.
loeb: the cosmic dawn
would've been spectacular.
new galaxies were forming
out of darkness.
this age of enlightenment was
a very dynamic period of time.
narrator: these great furnaces
start forging
the more useful ingredients
of the universe.
abel: all of a sudden,
it gets interesting.
for the first time,
new elements are being made.
they take hydrogen,
turn it into helium.
helium gets combined
to make carbon,
and we go to oxygen, and so
on.
narrator: deep in their
hearts,
the first giant stars
began the transformation
of matter,
producing the heavy elements
necessary for life.
they were huge
but so hot that they burned
through their fuel quickly.
abel: they can only live
for a very short time --
only a few million years.
that's really nothing.
we often say they're like
the rock stars in the
universe.
they live fast and die young.
and so, by the time
you make another one,
over here, this one
may already be ready to die.
narrator:
when they died, they died in
a hypernova --
the biggest explosions
ever seen in the universe.
stars were appearing
and disappearing.
it's like fireworks.
it's very dynamic.
loeb:
these were the very first
events
that spewed out
the heavy elements
and led to the formation of
the second generation of
stars.
narrator: for the first time,
stars were made,
light was produced,
and heavy elements were
forged.
and yet, the dramatic events
of the cosmic dawn
were still shrouded
behind a veil of fog.
abel: those first stars --
very bright, you know?
they could be a million times
as bright as our own sun,
giving off tons and tons
of light.
but the light's not getting
very far yet.
actually, most of it
gets sort of stopped
by all this fog of hydrogen.
narrator:
atoms of neutral hydrogen
filled the space
between the giant first stars.
abel:
as the light leaves the
surface of the st
it gets stopped,
so it couldn't get to us yet.
so the universe at this point
is still opaque.
narrator: tom abel uses
supercomputer simulations
to model these first stars
and the fog
to see how the universe
became transparent.
abel: what we'd like to do
is try and predict the past.
what we have here is
one of the first stars
forming.
there's a whole filament of
gas.
that was all that hydrogen
gas.
now, see, everything that gets
blue here gets really hot.
that's the ultraviolet
radiation
from this star
affecting everything
up to thousands of light-years
away from that star.
the radiation that they give
off, as it's trying to escape,
ionizes hydrogen gas.
but as a consequence,
you actually make things
transparent.
radiation hits the fog.
fog gets transparent.
now my boundary to the fog
is further away.
radiation in the next little
bit
can go a little further.
so, i make these bubbles.
narrator:
each star created a clearing
blowing a bubble
of transparent space.
abel: the simplest way to
think
about it is some swiss cheese.
as their light travels out,
it changes the "cheese."
our air bubbles are growing,
and we make ever larger ones.
in this way
of thinking about it,
at the end, we end up
with no cheese at all.
[ laughs ]
all the bubbles are so big
that the light from those
objects really travel freely.
narrator:
this image shows the cosmic
as the first light clears a
path
through the universe.
abel:
we're not even complete yet.
some parts of the universe
are still neutral and opaque.
but there it goes.
the whole fog lifts,
and all the galaxies
are revealed.
re-ionization would be
complete
somewhere in these pages.
narrator: tom's models
offer an explanation
for how our universe
finally became transparent.
shall we glue it in?
maybe with a light glue.
[ laughs ]
in case we have to correct it.
narrator: the theories and
computer models are valid,
but there's still testing
to be done in the real world.
narrator:
steven tingay is trying to see
but he's doing it
in an unexpected way.
he's trying to tune in
to radio hydrogen.
[ rock music playing ]
first light tonight
first light tomorrow
first light this morning
tingay:
well, in the early universe,
there were vast amounts
of hydrogen,
and each one
of those hydrogen atoms
can randomly give off
a radio wave.
and, so, we can tune
our telescope
to that radio frequency,
and then we're tuning in
to the hydrogen gas.
first light this morning
first light this evening
first light tonight
been looking back
narrator:
unfortunately, the band of
radio where hyd
is already filled with music
and news here on earth.
first, i was an ancient
hydrogen gas
produces radio waves
at a very specific frequency.
that's similar
to sort of f.m. radio
by the time they get to us.
so, it means that we've got to
build our telescopes
in areas where
there's no human interference.
so, you can't have f.m. radio.
you can't have tv.
you can't have mobile phones,
traffic on the road,
or anything like that.
first light tonight
first light this evening
first light this morning
distance is the only cure,
so we need to be in the middle
of nowhere, basically.
narrator: murchison county,
western australia,
is bigger than massachusetts
and rhode island combined,
but with less than
150 residents.
then i found it
i did it finally, oh
it's a terrible place
if you want radio, television,
or cellphone service.
i prayed till it was gone
my all in light
but it's the perfect place
to hear radio
from the beginning of time.
this is steven's telescope,
the murchison widefield array,
or mwa.
tingay: so, what we've got
here
are the antennas.
we have a cluster
of 16 of them here.
so, you can build
a lot of antennas
and get a very
sensitive telescope.
narrator: 2,000 antennas
spread
out over 1/3 of a square mile
are sensitive enough
to receive radio waves
that have traveled more than
13 billion light-years.
tingay: so, that gas outside
the
bubble produces the radio
waves.
no radio waves from the
bubble.
and so, for us,
we're sort of looking
for this swiss-cheese pattern
of bubbles and holes
in the hydrogen gas
distribution.
narrator: although it's not
possible to see the first
stars,
it should be possible
with this radio telescope
to find clues about the way
they cleared the hydrogen fog.
tingay: we don't actually see
the stars themselves.
we see the effect of the star
on its environment.
this is an actual image
made from the mwa data.
this is a patch of the sky
that's around about
30 degrees across,
so it's quite a big
chunk of sky.
so, we're looking through
our atmosphere.
we're looking
through our galaxy.
we're looking through
most of the universe.
if you look carefully down
here,
you can see many, many specks,
and these are all
galaxies or quasars,
millions, billions
of light-years away.
so, we need to remove
each of these signals one by
one
in order to peel back
those layers.
and, hopefully,
what we're left with
is just the signature of the
gas
and the first stars forming
13 billion years ago.
narrator: this radio signal
will be our first direct
contact
with the very first stars
in the universe.
tingay:
it's incredible to think
that in this very image
that i'm looking at right now,
that signal exists.
what's really special for me
is being able to look at this
while sort of sitting
in an ancient landscape
where we've actually built the
telescope and collected the
data
from these signals
that have traversed
billions of light-years
throughout the universe.
so, it's just astonishing
on a number of different
levels
for me.
loeb: we are all curious
where we came from.
we are now at a special time
that allows us to explore
these questions
scientifically.
we are able to peer
deep into space
and see those very early
sources of light
that tell us
how we came into existence.