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NARRATOR: Today we are unlocking the secrets of the cosmos--
exploding stars, super massive black holes
and screaming jets of gas.
Across the world and in space,
high-tech telescopes are picking up the signals
that reveal a hidden universe,
a cosmos almost incomprehensible in its size, age and violence.
WOMAN: Telescopes have continued to open up
vaster and vaster windows on the universe.
NARRATOR: Scientists are now racing to uncover new secrets.
With telescopes that are bigger, higher and more advanced
than ever before.
MAN: Every time you try and explore
a new part of the universe, we have these great discoveries
and these great surprises.
NARRATOR: Since the start of the 20th century,
telescopes have taken us beyond our planets
and beyond our galaxy
to see things we never dreamed of.
They've shown us the very birth of our universe,
invisible matter and the mystery of dark energy.
Will the next generation solve the biggest question of all,
our ultimate destiny?
WOMAN: Dark energy
is one of the keys to understanding the fate,
the ultimate fate of the universe.
pace,"
Major funding for NOVA is provided by the following...
And...
And the Corporation for Public Broadcasting
and:
Additional funding for "Hunting the Edge of Space"
is provided by:
To enhance public understanding of science and technology
in the modern world.
And by:
And:
(narrator) At the dawn of the 20th century
our galaxy, the Milky Way, was the entire known universe.
But now we live in the golden age of cosmic discovery.
Telescopes are exploding our understanding of the cosmos.
Bigger than ever and working
in giant networks across the globe and in space,
they are unlocking secrets that astonish and amaze us--
the planets of our solar system in breathtaking detail;
the majestic rings of Saturn;
and rolling storm clouds on the surface of Jupiter.
But far beyond our solar system we are now discovering
exoplanets orbiting other suns.
And beyond our galaxy,
another hundred billion galaxies,
like Andromeda...
Sombrero...
and Whirlpool,
each harboring hundreds of billions of stars.
We've detected supermassive black holes
spinning violently at the very centers of galaxies...
including our own.
We've witnessed supernovas--
exploding stars millions of light-years away
spewing out superheated gas
at 600,000 miles per hour.
And deep inside clouds of gas and dust
billowing trillions of miles high,
we can glimpse new stars being born.
Telescopes have continued to open up
vaster and vaster windows on the universe.
♪ ♪
(narrator) Now the latest telescopes
are revealing the invisible mysteries of space
that we are only just beginning to understand--
dark matter-- the hidden scaffolding
our entire cosmos is built on;
and dark energy-- a powerful and invisible force
that is pushing our universe apart.
Every time you try and explore
a new part of the universe
we have these great discoveries, these great surprises.
♪ ♪
(narrator) Back at the start of the 20th century
the universe seems to be a much smaller place.
The sun, Earth, and planets make up our solar system,
and beyond them are the millions of stars
that make up the rest of our galaxy...
the Milky Way.
But that's it-- that is our universe.
And for astronomers a major question remains.
A key question at the beginning of the 20th century was
whether or not our Milky Way was all there was,
was that the whole universe?
Or were there other galaxies?
(narrator) So what happened?
How did telescopes come to reveal
so much of our cosmos and reach to its very edges?
The revolution starts in the early 1900's.
A brand-new telescope is being built.
It will change our perception of the universe forever,
explode the edges of the cosmos
and set us on a voyage of discovery
that is still going on today.
(Alex Filippenko) That telescope is
one of the most important in the history of astronomy.
(narrator) The first steps in the revolution...
An astronomer is hiking up Mt. Wilson
a 5700-foot peak, high above Pasadena, California.
He's rising above the clouds and haze
of the lower atmosphere which distort telescopic images.
He wants to see if it is possible
to build an observatory at the very peak of the mountain
where the air is thin and crystal clear.
(Robert Smith) There was
a growing realization that for
really good astronomical seeing,
you had to find good sites,
rather than just build
a telescope where you happen to have an old observatory.
People had begun to realize that the mountains
in the west of the United States offered real possibilities.
(narrator) 100 years ago the simple idea of putting an observatory
on top of a mountain is revolutionary...
and an enormous logistical challenge.
Hundreds of tons of steel and concrete
have to be carefully hauled up the narrow mountain roads,
but the clear skies are worth it.
Mt. Wilson will become
the highest observatory on Earth and a blueprint
for observatories all over the world.
This observatory is the vision of one man,
George Ellery Hale.
His mission-- to solve the greatest mysteries in the cosmos
to find out if there is anything beyond our galaxy.
But for Hale, high altitude is just the first step.
To see deep into the cosmos with stunning clarity,
he needs his new observatory
to house the biggest telescope in the world.
Telescopes are like light buckets--
the larger the telescope, the more light it can gather,
bringing the faintest stars into focus.
But Hale faces a challenge--
most telescopes at the time use glass lenses to focus light,
but when glass lenses get really big,
they bend under their own weight, causing distortion.
Glass lenses just can't get any bigger.
What Hale needs is a radical new design--
a giant telescope that can collect a lot of light
but which doesn't use lenses.
So Hale turns to a telescope
first created by Isaac Newton in 1668-- the reflector.
This kind of telescope uses
a curved metal mirror instead of glass lenses.
It focuses light by reflecting it to a point.
Now, Hale is planning to build one
on a scale that has never been seen before.
Only revolutionary engineering
can support the gigantic instrument he plans.
And the project will take 11 years to complete.
The curved mirror spans 100 inches in diameter
and weighs 9000 pounds.
It sits at the bottom of a 40-foot cast-iron tube
housed in a 100-foot diameter dome.
Finally in 1917,
the biggest telescope the world has ever seen
sparks wonder amongst the public.
(male newsreel narrator) The scientific eye of America...
to this mecca of stargazers
flock astronomers from all nations.
(Wendy Freedman) In the pantheon of telescopes in astronomy,
Mount Wilson, it is no exaggeration to say,
is probably the most important telescope
in the history of cosmology.
Discoveries that were made here
really put it onto the map.
(narrator) This great telescope is soon directed
towards one of astronomy's most enduring mysteries.
Strange, fuzzy clouds of light hanging amongst the stars
have puzzled astronomers for years.
They are the nebulae.
Some are egg-shaped swirls,
others are delicate spirals of stars,
others have branching tentacles.
Thousands of them are visible through telescopes,
but nobody knows what they are or how far away they are.
Some astronomers believe that certain types of nebulae
could lie outside the edges of our Milky Way galaxy.
They wonder if they could be island universes,
galaxies like our own.
If so, this would shatter the limits of the universe
and our understanding of it.
But they have never had
the technology to solve the mystery...
until now.
Hale invites the world's best astronomers
to help crack the mystery once and for all.
Among them is a young man called Edwin Hubble.
(Alex Filippenko) Edwin Hubble was one of
the greatest observational astronomers ever to have lived.
He made a tremendous number of important discoveries.
(narrator) Night after night, Hubble examines the nebulae
with the 100-inch telescope.
He examines one in particular, the Andromeda Nebula,
which Hubble can now see in unprecedented detail.
(Michael Turner) It would be this 100-inch telescope
that would finally be powerful enough
to bring the nebulae within reach
and would start a series of discoveries
that just completely changed
our understanding of the universe.
(narrator) Hubble can see stars within the Andromeda Nebula,
but to find out if it really is
an island universe outside the Milky Way,
he has to find out how far away it is.
But that is not an easy task.
Establishing distances in the vastness of space
is one of astronomers' biggest challenges.
Stars, like car headlights
appear brighter the closer they are.
If you know their true brightness,
you can work out their distance.
It's like knowing the wattage of a light bulb.
If you don't know this, you have a problem,
as NASA astrophysicist Kim Weaver explains.
At that distance, the headlight on that car
appears to be the same brightness
as the headlamp on this bicycle.
(narrator) But as the headlights get nearer
it becomes obvious that their true brightness
is, in fact, greater than that of the bicycle lamp.
It's the same with stars.
If we know bright a star is intrinsically
we can work out how far away it is from us
and that's what we call a standard candle.
(narrator) Luckily for Hubble
astronomers had recently discovered
a special type of star
with a true brightness they can calculate.
It is called a Cepheid variable,
and it's recognizable because it pulsates over a period of days.
All Hubble has to do now is
find one of these stars in a nebula like Andromeda.
At night he scans the heavens with the 100-inch mirror.
By day he analyses the photographs he has taken,
hunting for any stars that have changed brightness.
Then, on October 6, 1923
after months of work, Hubble strikes gold!
A Cepheid variable on the edge of Andromeda.
(Wendy Freedman) I'm looking at the original discovery plate
of Edwin Hubble's where he first found
a Cepheid in the Andromeda galaxy.
And he actually marks on this plate, between 2 black lines,
where the position of the Cepheid is,
and he writes "VAR!"
when he realizes it's a Cepheid.
So he's compared 2 different plates, and he's discovered
that this thing is actually changing in its brightness.
(narrator) Hubble can now make a measurement
that will change history--
the distance to one of the nebulae.
He works out that Andromeda is
about 800,000 light-years away.
That's more than 8 times the distance
to the furthest-known stars in the Milky Way.
This means Andromeda has to be outside the Milky Way--
a whole new galaxy beyond our own.
This is irrefutable evidence; he's very excited.
He writes it with an exclamation mark because he realizes
the significance of the discovery.
(narrator) Hubble's discovery explodes the frontiers of our universe.
Our Milky Way galaxy is
no longer all there is in the cosmos.
Hubble goes on to discover that Andromeda is not alone.
He reveals that dozens of nebulae
are actually other galaxies.
Edwin Hubble's research with telescopes
profoundly changed our view of the universe.
The most powerful telescopes of today are still exploring
the wider cosmos that Hubble first discovered.
Looking across billions of light-years, they have uncovered
100 billion new galaxies beyond our own,
each made up of 100 billion stars.
Multiply those together and you have more stars
than all the grains of sand
on all the beaches and all the deserts on Earth.
Just like that, the universe
became 100 billion times larger.
(narrator) Hubble's discovery that there were
other galaxies outside our own
blows the universe wide open.
But what he discovers next
will be even more extraordinary.
♪ ♪
Several years earlier, other astronomers had discovered
that many of the nebulae,
now identified by Hubble as galaxies,
were moving away from us.
Now Hubble wants to work out why,
and he will do it by analyzing light itself.
He uses a method first discovered in the 1800's.
This is a spectroscope made
in about 1880, one of the first
generation of instruments used
for analyzing the light from the sun.
It's an instrument like this that transformed astronomy,
because you can decode the light
in a way that you'd never imagined.
(narrator) The spectroscope splits white light
into its rainbow spectrum of colors.
And hidden in this spectrum are clues
to the behavior of the stars.
Light is made up of waves,
and each color has it's own wavelength.
Blue light has a short wavelength.
Red light has a longer wavelength.
But when a galaxy is racing through the cosmos,
the wavelengths of light appear to change
from our perspective on Earth.
If the galaxy is moving towards us,
the wavelengths get squashed and appear more blue.
If the galaxy is moving away from us the wavelengths
get stretched out and appear to become more red.
We call the effect redshift.
It's like a cosmic speedometer.
The faster a galaxy is moving away from us,
the more its light waves are stretched towards the red.
Sound works in much the same way
because it too is made up of waves,
as astronomer Alex Filippenko explains.
(engine revs up)
♪ ♪
Ah, this is going to be great!
I'm going to blare on the horn now. Here we go.
(steady blast of the horn)
The pitch of the sound is constant
even though the car is speeding down the road.
(narrator) In the driver's seat,
Filippenko hears the horn at a constant pitch.
It doesn't change.
But now he wants to hear what the horn will sound like
if he stands on the roadside, and the car drives past him.
(blast of horn increases in intensity and pitch)
(blast of horn decreases in intensity and pitch)
When the car was coming towards me, the waves from the horn
were being squished together, so the pitch sounded higher.
As the car came passed and moved away,
the waves were stretched apart, so the pitch sounded lower.
So it sort of went nrrreeeoiii, like that.
(horn's pitch increases, then decreases)
If that blue car had been going fast enough,
the high-frequency blue light would have been stretched apart,
then the blue color would have shifted all the way to red.
The car would have looked red to me.
That's known as a redshift.
♪ ♪
(narrator) Back in 1928, Hubble is
looking at the redshift of his new galaxies
to find out how fast they are moving.
He sets out to chart the speeds of galaxies both near and far.
He wants to see if he can find any correlation
between how fast they're moving and how far away they are.
Night after night is spent
painstakingly analyzing the light from galaxies.
The final results are staggering.
Hubble discovers that the farther away a galaxy is,
the greater its redshift, so the faster it is moving away.
By 1929, he had established
a very interesting relationship
between them-- the nebulae
that are farther away are moving faster away.
(narrator) Hubble comes to an astounding conclusion--
the universe is expanding.
The galaxies may look like they are traveling away from us
but in fact, it is space itself that is stretching apart.
Here's a good analogy of how the expanding universe works.
Here's a hypothetical, one-dimensional universe,
where the ping-pong balls are the galaxies,
and the hose is the space between them.
As the space expands,
all the ping-pong balls recede away from one another.
And every bit of space expands.
The more space there is, the faster the distant one
looks like it's expanding away from us.
(narrator) Hubble's discovery is one of
the greatest breakthroughs in the history of astronomy.
The universe is not static.
It is growing bigger and bigger.
These galaxies are moving apart from one another
because space itself is expanding between the galaxies.
That was a marvelous discovery.
(narrator) Hubble could never have made his discoveries
without the 100-inch telescope on Mt. Wilson.
High above the plains of New Mexico,
one of the most advanced telescopes of today is taking
Hubble's groundbreaking work even further.
The Sloan Digital Sky Survey is analyzing starlight
from hundreds of thousands of distant galaxies.
Each aluminum disk is a galaxy map
for a small part of the night sky.
(Stephanie Snedden) So we've got 640 holes
on an aluminum plate, each hole corresponds to a galaxy
many millions of light-years away.
(narrator) Optic fibers link each hole to a hi-tech version
of the spectroscope used by Edwin Hubble.
It will measure the redshift of the galaxies.
Then technicians insert the map into the base of the telescope.
And match it up to the right section of the night sky.
So you can get 640 spectra at once,
which is a great way to get a survey done,
much better than one at a time.
(narrator) This survey has now calculated
the speeds of over 930,000 galaxies,
giving us a far more precise image
of the universe we live in and how fast it is racing apart.
But back in 1929, Hubble's discovery begs a new question--
If the universe is expanding, what is it expanding from?
Hubble saw and realized
that things were moving away from each other
and the natural leap from that is, well,
if things are now moving away,
weren't they all at some time in a central location?
(narrator) Astronomers put forward a revolutionary theory--
the big ***--
a single moment in time when the universe was born.
The idea is so revolutionary,
scientists struggle to make sense of it.
(Kim Weaver) We had no way to observe this phenomenon.
It made no sense to people at the time.
Even Einstein didn't believe in this idea.
We didn't have the belief that it might happen
and we also didn't have the telescopes
to observe the effects of the big ***.
(narrator) To find the proof, astronomers will need
a completely different type of telescope--
one that can see what our eyes cannot.
Beyond the colors of visible light
are the rays of the electromagnetic spectrum
that our eyes cannot detect--
gamma rays, X-rays,
radio waves and microwaves may be invisible,
but they are crucial for astronomers.
They hold the keys
to some of the most violent events in the universe.
The human eye is only sensitive
to a very small part of the electromagnetic spectrum,
these are all the waves that behave like light.
But we have been able to see in parts of the spectrum
which are not visible to the human eye.
(narrator) 1964...
astronomers Arno Penzias and Robert Wilson,
are working with a new radio telescope.
Its giant antenna enables them to measure microwaves
and radio waves in space in the form of heat.
They expect the stars of our Milky Way to emit a faint glow,
but when they point their antenna to empty space
where there should be nothing at all,
they discover something very unusual.
(Arno Penzias) We expected to find
the sky away from the Milky Way
to be quite cold, I mean, very close to absolute zero.
Instead we found to our very great surprise
that it was about 3 degrees hotter than that.
(narrator) The mysterious signal seems to come from every direction.
(Arno Penzias) We had a noise, a signal if you want to call it that.
It could be radio noise sources or something else.
I had no idea what it was.
(narrator) Penzias and Wilson suspect that there is a defect
with the equipment which is causing interference.
They try everything... even sweeping
the pigeon droppings from inside the antenna.
(Arno Penzias) It didn't go away
through winter or summer, day to night, seasons.
We looked at every possible direction.
There was a high altitude nuclear explosion
2 summers ago, so maybe there was something
in the atmosphere charged particles--I didn't know.
(narrator) Penzias and Wilson are at a loss,
until they hear about the work being carried out
by a team of scientists
just down the road, at Princeton University.
Robert Dickie and his colleagues have worked out
that the afterglow from the big *** should still be felt today.
They have even calculated the temperature--
3 degrees above absolute zero.
So I called up, and I got Bob Dickie's office,
and I happened to get him.
And what I learned afterwards was that he put down the phone
and he turned to his colleagues
and he said "Boys, we've been scooped."
(narrator) Penzias and Wilson have unwittingly found
the first physical evidence of the big ***.
Their radio telescope has picked up
the afterglow of the beginning of the universe.
It remains one of
the most important discoveries of all time.
I had no idea that we were
listening to the echo of creation.
(narrator) In 1978 Penzias and Wilson received the Nobel Prize.
(Arno Penzias) To be on a list with Albert Einstein,
to be on that same row,
was almost too much, it was too much to bear.
I just couldn't think of comparing myself
against the people who have won Nobel prizes.
In 1964, when the background radiation from the big ***
was discovered, it was for the first time direct evidence
that there was a hot big ***-- an origin to the universe.
Penzias and Wilson have found direct proof for the big ***.
But it will take another 37 years.
And far more sophisticated microwave technology
before we discover how the big ***
formed the universe we see today.
Heading to an orbit 1 million miles from Earth
is the Wilkinson Microwave Anisotropy Probe, or WMAP,
a superadvanced version
of Penzias and Wilson's giant antenna
armed with 2 reflecting telescopes
WMAP's mission is to examine the afterglow
of the big *** in extreme detail
and to try and find out why galaxies formed.
With WMAP we were trying to look way back
to the very, very earliest times in the universe.
(narrator) After a year of recording,
the first results are mapped.
(Wendy Freedman) The WMAP observations were incredible.
Instead of a smooth background radiation,
you could measure to 1000th of 1%
changes in the temperature across the sky.
(narrator) WMAP shows that actually
there are tiny fluctuations in temperature.
(Chuck Bennett) The dramatic looking temperature changes here
are actually tiny, going from a redder hot spot here
to a bluer cold spot is only a change
of a couple of millionths of a degree.
So it's really tiny temperature changes
but a really dramatic pattern over the sky
which has revealed tremendous information to us.
(narrator) The tiny red spots are
where matter is beginning to come together
and where clusters of galaxies will eventually form.
This is vital evidence--
clues to how stars and galaxies first came into being.
The WMAP data helps astronomers work out
what happened at the very beginning of the universe,
right after the big ***.
We can actually deduce from that
things that happened in the first
trillionth of a trillionth of a second of the universe.
I think that's just extraordinary to be able
to probe that early in the history of the universe.
(narrator) And WMAP's accuracy
allows astronomers to solve another great cosmic mystery--
the exact age of the universe.
For the first time, astronomers have an accurate figure.
We now know that the universe is
about 13.7 billion years old.
That's very old but it's not infinite.
It could have been infinite, but it's not--
one of the great discoveries of 20th-century science.
(narrator) WMAP has taken us further from the Earth
and closer to the very birth of the cosmos
than any other telescope in history.
It is revealing the edges of the universe
in unprecedented detail.
But the microwave data it records
is invisible to the human eye.
Would it ever be possible
to see the very first galaxies in the universe
in ordinary, visible light?
Only if optical telescopes also take a giant leap in technology
and head for the skies.
(man) Liftoff of the space shuttle "Discovery"
with the Hubble Space Telescope--
our window on the universe.
(narrator) NASA launches
the most famous telescope ever built.
If you ask any person on the street
to name a telescope, they will say the Hubble Space Telescope.
The Hubble Space Telescope is probably
the most productive telescope in history.
It has been compared to the time when Galileo
lifted his telescope to the sky for the very first time.
(narrator) The 12-ton Hubble Space Telescope is a fitting tribute
to the man who first took us beyond the edges of our galaxy.
It bursts through Earth's atmosphere
and is released into orbit 370 miles above us.
Ever since Hale built his observatory on a mountaintop,
astronomers have dreamt of having a telescope in space.
Here, far above the interference of the Earth's atmosphere
there's no haze, smog, or cloud
to obscure the light streaming in from the universe.
Putting a telescope in space
gives us an incredibly clear view of the universe.
We have seen further and deeper with the Hubble
than any other telescope in history.
(narrator) And Hubble is looking at light that is visible.
(Matt Mountain) What we're able to do with the Hubble
is essentially capture the images
as though you had 2-meter eyes and you were in a vacuum,
and you could hold them open for a week.
This is what you would see.
They're not computer creations, they're actually
digital pictures that you can actually see.
(narrator) The crystal clear images taken by Hubble are
some of the most extraordinary visions of space ever seen--
the remains of exploding stars streaming through space;
vast clouds of gas and dust
where new stars are being born;
distant galaxies, spiraling in giant disks
and colliding to create supergalaxies.
My favorite image I think must be the Butterfly Nebula.
It's a nebula that has gas streaming out
at 600,000 miles an hour.
♪ ♪
Telescopes are time machines.
We're seeing photons that actually started their journey
13 billion years ago and have taken that long
to traverse interstellar space to us.
And so you're not only looking out into space,
you're looking back in time.
(narrator) In 1995, Hubble's ability to look back in time
is put to the test.
Astronomers decide to turn its gaze
onto one dark point in the universe
just to find out what they can see.
We picked one tiny point in the sky in which there was,
essentially, nothing there, or nothing special there.
We stared for 10 days at a single dark spot on the sky.
(narrator) It is as if Hubble was peering through a tiny keyhole
of our Milky Way galaxy to the universe beyond.
The size of the spot that
we looked through was no more than a drinking straw.
(narrator) What Hubble sees is extraordinary.
And what we saw were 10,000 galaxies in that single spot.
(Mario Livio) Every point of light that you see in the image
represents a galaxy with 100 billion stars like the sun.
(narrator) The image is called the Hubble deep field.
It shows light from galaxies 4 billion times fainter
than anything we can see with the human eye,
light that set out on its journey billions of years ago.
If there is something that gives you a sense
of the size of the universe and its depth,
it's this kind of image.
(narrator) Every time the Hubble Space Telescope
has been serviced by astronauts,
the camera has been upgraded.
After NASA's final mission in 2009,
a new deep-field image reveals
the furthest galaxies ever seen--
only 600 million years after the big ***.
We're seeing back as far as we can see because
we're seeing back to the time of the birth of the galaxies.
(narrator) The Hubble Space Telescope is taking images
that continue to amaze us.
(Mario Livio) I believe that the Hubble Space Telescope
in some sense has been really unique
in the history of science.
It has taken really the excitement of discovery
and has made it, you know,
to belong to every home, to humans all across the globe.
(narrator) Hubble has revealed the mysteries of our cosmos
in stunning glory.
Now it is working within a vast network of modern
supertelescopes to investigate a discovery
that has rocked the world of astronomy,
a discovery that threatens to turn everything
we thought we knew about the universe on its head...
an enigmatic force called dark energy.
Dark energy is
the most mysterious thing we have ever discovered.
(Matt Mountain) It's an energy that seems to be created out of nothing,
out of a vacuum. But we have no idea what it is.
(narrator) Dark energy's discovery comes as a complete surprise.
In the mid 1990's on Mauna Kea, Hawaii
at the Keck Observatory, a team of astronomers
including Alex Filippenko is scouring the distant cosmos.
but will it really expand forever?
They have a theory-- the universe might
actually stop expanding and start slowing down.
Just like when I throw this apple in the air,
the gravitational attraction of the Earth on the apple
slows it and eventually stops it
and reverses its motion, so too, all the galaxies
pulling on each other could slow down
and ultimately stop the expansion of the universe,
to be followed then
by the collapse of the universe into a big crunch.
(narrator) So is the universe
really beginning to fall back in on itself?
To measure the speed of the very edges of space,
astronomers need the most powerful telescopes on Earth.
The giant mirrors of the Keck telescopes
are 33 feet in diameter.
Made not from one single disk of glass,
but 36 hexagonal mirrors working together.
They give a single image of exceptional clarity.
(Alex Filippenko) The Keck telescopes are really fantastic devices.
They can allow us to see galaxies that are
literally at the visible edge of the visible universe,
10, 11, 12 billion light-years away.
(narrator) But to find out how far away
these distant galaxies actually are,
astronomers need a standard candle,
a star that will act as a cosmic yardstick.
But the Cepheid variable stars that Edwin Hubble used
are too faint at the extremities of the cosmos.
The astronomers need to hunt
for an especially bright kind of star
inside the furthest galaxies.
The deaths of these stars cause
some of the most devastating explosions known to humankind.
They are called supernovae.
A supernova is quite literally an exploding star.
Now, most stars don't explode at the end of their lives,
but a few completely disrupt themselves
in a colossal, titanic explosion.
(narrator) And not just any type of exploding star will do.
They are looking for a type of supernova that explodes
with a very intense and consistent brightness--
a Type 1a.
They go off as a gigantic nuclear runaway.
They are essentially a gigantic nuclear bomb.
(narrator) In the most distant galaxies of the universe
they find what they are looking for--
Type 1a supernovae.
There it is there it is.
Look at that! It's a little bit fuzzy.
(narrator) Now they measure the redshift to calculate how fast
these distant galaxies are moving away.
Finally in 1998 after years of research,
they come to a shocking conclusion--
the expansion of the universe isn't slowing down at all.
It's speeding up.
Much to our surprise, we found
that the universe is expanding faster now than it used to be.
So instead of slowing down, it's been speeding up.
So it's like the apple goes "zzzzoom," like that.
A completely fantastic conclusion.
(narrator) A mysterious force that no one can see
is defying gravity,
pushing the universe apart faster than ever.
It is the force astronomers now call "dark energy."
There is the possibility that Einstein's gravity
is incomplete, that we don't understand gravity.
There is the possibility that it could change
some of the fundamental laws of physics.
(narrator) But what dark energy actually is
and what it will do to our universe
remains a mystery to this day.
Dark energy is one of the keys
to understanding the fate, the ultimate fate of the universe.
Is it going to expand forever?
(Michael Turner) Will it continue to speed up? Will the speedup speed up?
In which case the universe gets ripped apart.
(narrator) The one thing astronomers do know
is that dark energy makes up most of the universe.
(Mario Livio) We discovered since that this dark energy
is some 72% of the energy density of our universe
and yet we don't know what it is.
I mean, just so you understand the level of the puzzle,
about 70% of the surface of the Earth is covered with water.
Imagine we didn't have a clue what, what water was--
this is the situation we're in.
(narrator) As if one invisible mystery isn't enough,
scientists at NASA's Jet Propulsion Lab
are investigating an equally mysterious
invisible substance-- dark matter.
Dark matter is basically invisible.
We can only see it by looking at how it distorts things
that are behind the dark matter.
(narrator) Images taken by the Hubble Space Telescope
are now helping to reveal
where dark matter can be found in the universe.
Hubble's images show
that this invisible substance is bending light.
(Jason Rhodes) A good analogy is a pool of water.
If you went out and threw a penny
to the bottom of the pool, you would look down at that penny
and you can see the penny very clearly
because the light fromhe penny is coming through the water.
The water is essentially invisible, but the shape
of that penny is distorted because that light travels,
not a straight path, but a slightly curvy path
through the water to come to our eye.
(narrator) Dark matter has a similar effect.
It exerts a powerful gravitational pull
on light from distant galaxies.
(Jason Rhodes) So what we're looking at here is light from a distant galaxy
coming to us through this dark matter distribution
and as the light comes through the dark matter distribution,
the path of the light is bent.
(narrator) Astronomers calculate that dark matter
makes up 23% of the universe.
Add that to dark energy and that leaves
just 5% of the entire universe that is not invisible.
So after 400 years of searching the heavens with telescopes
we still have 95% of the universe to reveal...
and a new quest is beginning.
A new generation of telescopes millions of miles in space,
high on mountaintops, and deep below the Earth
is gearing up to change our understanding once again.
Telescopes are actually at the forefront
of changing the way we think of the universe
because it's the only way to see the universe.
(Wendy Freedman) So these big, giant, new telescopes
are trying to address some fundamental questions--
what's the nature of the universe we live in?
What's the stuff that makes up the universe?
Could there be life elsewhere in the universe?
(narrator) The most sensitive scientific instruments today
are not just looking at detectable light.
They are searching for the invisible,
and they will reveal mysteries of the cosmos
beyond our wildest dreams.
(Kim Weaver) There's a whole hidden universe out there,
and that's what we're trying to discover.
(narrator) Since the time when telescopes
were first raised towards the heavens,
we ha been hunting the edges of the universe.
Revolutions in technology and the race to build bigger,
higher, and even in space
have given us discoveries that have been revelatory,
earth-shattering, and profound.
We now know how little we are
compared to the extraordinary size of our universe.
(narrator) We are even on the brink of discovering planets
with the building blocks for life.
(Wendy Freedman) Are there Earth-like planets?
Could there be life elsewhere in the universe?
One of the exciting things about these big telescopes--
they're very likely to give us the answers to these questions.
(narrator) At each stage
we have pushed the boundaries of our universe further
beyond our planets, beyond our galaxy,
beyond the hundred billion other galaxies,
and virtually back to the big ***...
and the beginning of time.
Telescopes are changing everything
we thought we knew about our tiny planet
and its true place within the cosmos.
Who knows what they will reveal in the future?
We're gonna look back in another 100 years--
I think the whole world
and our view of it will be ansformed yet again.
♪ ♪
for NOVA
And...
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and:
Additional funding for "Hunting the Edge of Space"
is provided by:
To enhance public understanding of science and technology
in the modern world.
And by:
And:
On NOVA's "Hunting the Edge of Space" website,
see the next generation of giant telescopes
and learn more about our cosmos,
filled with black holes, dark matter, extrasolar planets
and other mysteries.
Find it at pbs.org.
This NOVA program is available on DVD at shopPBS.org,
or call 1-800-play-PBS.
Captioned by Media Access Group at WGBH access.wgbh.org