ALAN ALDA Once we thought our world was the center of the
Universe. Today we know we're on a minor if privileged planet
circling an average star in an inconspicuous spot in an unremarkable
galaxy that's just one of billions of galaxies occupying a
Universe that stretches farther than we can see -- even with
our biggest telescopes. But in the last few years telescopes
like these here in Chile have shown us that we are even less
at the center of the Universe than we could ever have imagined.
You and me and these rocks and the sun that shines on us and
the stars that twinkle overhead aren't even built of the same
stuff that most of the Universe is made of. And there's a
mysterious force out there in space that literally comes out
of nowhere. It's a force that seems to be pushing the Universe
apart faster and faster - until one day everything out there
beyond our own little solar system will simply disappear into
blackness. Our Universe - and our place in it - just got a
whole lot weirder.
ALAN ALDA (NARRATION) Staring at a patch of sky one-tenth
the diameter of the moon, the Hubble Space Telescope recently
peered farther out into our universe - and farther back in
time - than any telescope before. For a million seconds it
gazed, gathering light from 10,000 galaxies. The smallest
and faintest are some 13 billion light years away, meaning
their light has been traveling toward us since shortly after
the Universe began. What gave birth to these first galaxies
is one of the great mysteries of our Cosmos. But astronomers
now suspect that matter we can see in the Universe -- including
ourselves -- resulted from a titanic struggle between a form
of matter we can't see - Dark Matter - and a force - Dark
Energy - we've only recently detected. Together, Dark Matter
and Dark Energy rule our Universe; and we're here to wonder
about them only because in their battle for domination -which
has gone of for most of eternity -- neither has triumphed.
MISSION CONTROL Two, one, main engines start and lift-off
of the Delta 2 rocket with the MAP spacecraft exploring the
past and future of our Universe.
ALAN ALDA (NARRATION) This was the launch on June 30th, 2001
of a spacecraft able to look even farther back in time than
the Hubble. Called WMAP, its mission was to capture the very
first light of the Universe. That light has been traveling
toward our own little corner of the Cosmos ever since it was
released from what most astronomers now agree was the origin
of everything we can see… planets…stars… galaxies like our
own Milky Way… and the billions of other galaxies that have
been expanding outward since the beginning. That beginning
was the Big Bang, a ripping open of space and time inflating
in an instant to become an unimaginably hot cauldron of energy
and matter. It was light escaping from that cauldron that
the WMAP satellite was sent to detect and measure - light
now reduced by its journey through eternity to a faint afterglow
called the cosmic microwave background radiation. What the
satellite saw has been mapped onto something I can comfortably
get my hands around - if not yet quite my head.
ALAN ALDA This device, this satellite, is picking up this
cosmic background microwave radiation from way back in time,
from the beginning of the Universe.
CHUCK BENNETT It's actually a direct picture of what the
Universe used to be like, because it took that light all that
time to get from there to the satellite.
ALAN ALDA OK, here's the thing… You have to help me visualize
this. A lot of us when we first hear about the Big Bang think
of it as an explosion happening in a point of space and moving
out, and then somewhere we're in there or something. And a
lot of us think when you look back in time, we want to look
back to that point. But on the contrary, when you look back
in time you're looking in every direction, you're looking
all over some shell. And everywhere you look it's as far back
as you can go. How could that be? Can you give me an image
that helps me grasp that?
MAX TEGMARK You're trying to think of an explosion that happened
in one place.
ALAN ALDA Yeah, I know, I know.
MAX TEGMARK And instead the Universe today doesn't have any
particular center and it never did. Everywhere you were, you
would have gone, it would have been expanding. I like to think
of baking a loaf with little raisins in it, and when the bread
rises all the raisins are moving away from all the other raisins,
no raisin can really claim that it's in the center of this
expansion any more than any other, right? And this is the
same way we need to think of our space.
ALAN ALDA I know, but here's the problem. Every time one
of those raisins wants to look at another raisin, it can look
all the way across the loaf to a raisin on the other side.
But if it looks in the other direction it sees the baking
tin. That's a little bit different.
MAX TEGMARK That's because the bread is finite and we live
in maybe an infinite space. If you live in an infinite loaf
of bread there's nothing you can do to tell the difference.
CHUCK BENNETT The picture of an explosion as a ball of stuff
is I agree that that's what many people think of, but that's
just wrong. It's not what the Big Bang theory is all about.
What the Big Bang theory is all about is space itself, think
of it being stretchy and constantly stretching between every
object everywhere, so that everything is getting farther away
from everything else, and no matter where you are and you
look out you see a glow left from the initial Big Bang.
ALAN ALDA So it needs to be called the big taffy pull instead
of the Big Bang.
CHUCK BENNETT That would be a better name.
MAX TEGMARK It should be infinite then.
ALAN ALDA The infinite taffy pull. Well, I think we're getting
closer. OK, show me what the implications of this mapping
are.
MAX TEGMARK Well, what I love about, what I really love about
Chuck's beach ball is that it represents this very basic fact
that even though space itself may be infinite, we can only
see a finite volume. It's a huge volume, this is about 13
billion light years in radius, but it's still only finite.
So we're in the center of this and the most distant thing
we can see is this hot glowing wall of hydrogen plasma, which
is opaque. We just can't see what's on the other side.
ALAN ALDA (NARRATION) But on the side of the wall we can
see - actually the inner surface of the beach ball - the incandescent
plasma just beyond has cooled enough to go from being uniform
and featureless to having eddies and ripples. It was these
tiny imperfections that were imaged by the exquisitely sensitive
eyes of the WMAP satellite.
MAX TEGMARK Chuck and his colleagues have stretched the contrast
here by a factor of 100,000, to prevent it looking completely
uniform. But there are nonetheless these tiny ripples where
some places look hotter and some places look colder and that's
just because there's a tiny bit more stuff in some directions
than in other directions. And these little ripples are extremely
important because it's because of them that we're here. You
know if you had something that was extremely uniform it would
stay uniform forever, it would never make clumps, planets,
and we couldn't be here talking.
ALAN ALDA (NARRATION) To find out more about how those faint
early ripples left over from the Big Bang became our Universe
we've come here to the foothills of the Andes in Chile. This
region has become home to some of the world's biggest and
most powerful telescopes, lured here by clear skies and a
smooth flow of air off the Pacific Ocean that reduces atmospheric
turbulence, making for what astronomers call superb "seeing."
This is the site of one such observatory, Las Campanas, run
by the Carnegie Institution of Washington --- and the principle
research site of an old friend of Frontiers, Alan Dressler.
ALAN DRESSLER Welcome to Las Campanas Observatory and the
Magellan telescopes.
ALAN ALDA There seems to be two of them.
ALAN DRESSLER There are two, there are twin 6 1/2 meter telescopes
which means they have mirrors that are about 22 feet across,
which is a good size, and they collect light from distant
stars and galaxies, and this is where we do most of our research.
ALAN ALDA (NARRATION) That research is focused on the formative
years of the Universe.
ALAN DRESSLER At the beginning we know there was a very simple
distribution of matter, it was very smooth, it was a very
simple distribution of elements, hydrogen and helium, there
were no stars, just gas. How did the Universe go from being
deadly dull, with no variation, to tremendously complex so
that there are creatures on it that look back and figure it
all out? That's the fundamental question. And this zone, this
sort of 3 billion years in to maybe 8 is where most of the
complexity grew, and we can see that evolving, happening,
by this strange ability to look back in time. I mean only
in astronomy can you look back and see 5 billion years, 10
billion years into the past, you can see the past, because
it took the light…
ALAN ALDA All those stories about time machines, we got one,
we're looking at it. The light from the stars comes in through
that mirror…
MIGUEL ROTH Exactly. Gets reflected on another mirror up
there, which in turn reflects then the light through the hole
in the black turret where there is another mirror, a diagonal
mirror at 45 degrees that deflects the light into the instrument.
ALAN ALDA When the light hits that mirror, how long has it
been traveling?
ALAN DRESSLER Well, for the things I'm looking at with Pat
tonight, the light has been traveling for about 10 billion
years. So pretty much the whole age of the Universe. And this
is the first thing it hits in all that time. So it's got to
be clean!
ALAN ALDA (NARRATION). Especially tonight - because it's
the first time Alan will be using a brand new instrument.
ALAN DRESSLER Alan, this is Pat McCarthy, my science partner
here. This is the slit mask.
ALAN ALDA (NARRATION) In what they call affectionately the
wok, Pat has painstakingly cut tiny holes corresponding to
the galaxies he and Alan plan to study.
ALAN DRESSLER In any area of the sky that we pick up, say
a half a degree across, that's what this is looking at, that's
the size of the moon, there would really be 100,000 galaxies,
very faint, very distant galaxies, and we have selected in
this case 700 of them we want to look at. So we must make
sure the light from those 700 goes through the spectrograph,
but nothing else.
ALAN ALDA (NARRATION) Alan's new instrument doesn't just
take pictures of those distant galaxies: it can read their
spectra. In fact, nearly everything we know about stars and
galaxies comes from analyzing their light with the aid of
a prism or - more commonly - a device called a diffraction
grating.
ALAN DRESSLER When sunlight, or any light, strikes this,
it's spread by color into its component colors. You can say
how much red light, how much green light, how much blue light,
tells you something about the temperature of the sun, and
the sun is a star at 5000 degrees temperature, produces a
lot of yellow light and so the middle of the spectrum, in
the most intense part, is yellow green.
MIGUEL ROTH That we can see almost with our bare eyes. We
can see red stars and bluer kind of stars, that has to so
with the temperature of the star, basically.
ALAN ALDA (NARRATION) Here, for example, in one of the first
images taken with Alan Dressler's new camera, both red stars
and blue stars are visible in a galaxy nearby. But in the
spectrographs astronomers use, the colors of a star can be
analyzed in much finer detail than is visible in a rainbow.
There are dark lines and bright lines at precise locations
across the spectrum that reveal what a star is made of as
well as its temperature and its size.
ALAN DRESSLER The reason that's important is different stars
of different sizes last, they live, a different amount of
time. The sun will last 10 billion years, it's halfway through
its lifetime. A star much more massive than the sun might
only live for one billion years. So if we can find those,
we know that those are young stars, they cannot be any older
than one billion years old, because they would already be
gone.
ALAN ALDA Yeah, yeah.
ALAN DRESSLER So when I look across our galaxy I could do
them one by one, I could tell you what each individual star
is like. I could see a star like the sun all the way across
our galaxy. And it I put together the light from billions
of stars, I can see them all the way across the Universe and
in that information is the rate at which new stars are being
born in that galaxy, 3 billion years ago, 5 billion years
ago, 7 billion years ago, so I begin to build up a picture
of how rapidly were galaxies turning their gas into stars
over their lifetime. A complete construction project.
ALAN ALDA (NARRATION) With twilight, the Magellan telescope's
dome is opened.
PAT MCCARTHY We need to rotate 0.335 degrees, plus, 0.335,
tres, tres, cinquo.
ALAN ALDA So how many galaxies are going to have their spectra
taken?
PAT MCCARTHY We're going to take the spectra of 700 galaxies
tonight.
ALAN ALDA Seven hundred.
PAT MCCARTHY Yeah, that's probably as many as has ever been
done. I've got to remember to put in the wok, because that's
a big mistake if you don't do that, you've really blown it.
ALAN ALDA (NARRATION) This first exposure using the wok took
a half an hour.
PAT MCCARTHY OK, so already we can see some objects, that's
encouraging. There's a bright one.
ALAN ALDA (NARRATION) This is just the beginning of several
months' work that will add up to some 50 hours of data. But
even from these first few minutes of peering across the Universe,
a trickle of light has left the signature of a galaxy in the
full fury of creation.
ALAN DRESSLER So here is a very faint line that is a very
faint galaxy, very far away, and here is this one color that
represents probably 100 photons of light coming from a place
where a million hot young stars have formed in that galaxy
ten billion years ago.
ALAN ALDA So ten billon years ago and all that made it to
us tonight were 100 photons?
ALAN DRESSLER A hundred photons, that's right.
ALAN ALDA So this is the first scientific run you've done,
right?
ALAN DRESSLER Yes, new instrument.
ALAN ALDA How do you feel, is it a good start?
ALAN DRESSLER It's a good start. I wish we'd seen a lot more
in the first exposures, but you've got to have a lot of patience
if you're going to do something really hard. But it works.
The instrument works. It's producing spectra.
ALAN ALDA You've been working on this instrument for how
long now?
ALAN DRESSLER Six years.
ALAN ALDA Six years.
ALAN DRESSLER Took a long time to build, but now it's going
to pay off for us.
ALAN ALDA (NARRATION) That pay-off will help illuminate one
of the Universe's darkest secrets - how those early ripples
left from the big bang became the seeds of the stars. A vital
clue to that mystery was discovered because a little girl
loved watching the movement of the stars in the night sky
outside her bedroom window. That story next.
Dark Matter
ALAN ALDA (NARRATION) In the early 1970s, Vera Rubin was
a rare young woman in the traditionally male dominated world
of astronomy.
VERA RUBIN I got interested in astronomy by watching the
stars as they moved outside my window. I had a window that
faced north, I had a bed under the window and I could see
during the night that the stars changed their positions. And
that's really what got me interested in astronomy. So I guess
I was always interested in how things moved.
ALAN ALDA (NARRATION) Vera decided to look at how stars moved
as spiral galaxies - like our own Milky Way - revolve majestically
in space. Most astronomers then studying galaxies were drawn
to their centers, where the stars are densest. But as a then
shy young graduate student, Vera looked instead to where galaxies
trail off into empty space.
VERA RUBIN I had children and I didn't want to compete with
what other people were doing. So I decided to study the outsides
of galaxies.
ALAN ALDA (NARRATION) What she discovered there was revolutionary
-- in both senses. In our solar system, the planets revolve
more slowly the farther they are from the gravitational attraction
of the sun. Galaxies were assumed to rotate similarly, with
stars moving more slowly the farther they are from the center.
Instead…
VERA RUBIN I found that the stars very far out were going
just as fast as those near the center, sometimes even faster.
ALAN ALDA Sometimes faster?
VERA RUBIN Sometimes faster, and well beyond where there
was no light. In fact, I brought - I went to my office this
morning and got this. Here's the Andromeda, which is the largest
galaxy, largest spiral, near us. At our position in our galaxy,
which would be maybe a third of the way out here, we are moving
at half a million miles an hour around the center of our galaxy.
ALAN ALDA You can hardly feel the wind.
VERA RUBIN That's right. And you don't notice it because
everything around us, all the stars near us, everything, is
going just at the same speed that we are. So here are the
velocities of stars and gas all the way across. Newton's Laws,
because this is where the luminosity is, would predict that
the velocities rise and then fall rapidly, so that by the
time you get to what looks like the edge of the galaxy, the
stars would be moving almost negligibly, very, very slowly.
So what you see instead is they're moving very, very fast,
all the way out there.
ALAN ALDA So when you got that information then, did you
think you were wrong?
VERA RUBIN No.
ALAN ALDA You knew you were right.
VERA RUBIN I never thought…
ALAN ALDA You never thought you were wrong?
VERA RUBIN No, I had some crazy ideas, and then shortly settled
with what would have to be, that matter that isn't luminous,
that you don't see, the galaxy has to extend that far out,
there has to be something, there has to be matter that's gravitationally
accelerating the little bit of gas that we could see.
ALAN ALDA (NARRATION) There had been hints of invisible matter
in the Universe before, but Vera Rubin's startling discovery
confirmed it. Her observations implied, in fact, that galaxies
are embedded in immense halos of Dark Matter, invisible to
our telescopes, and yet making up most of the actual mass
of each galaxy, including our own.
VERA RUBIN The whole concept of Dark Matter is enormous.
It means that when you're looking at the sky you're only looking
at a few percent of the Universe, that most of the Universe
is invisible.
ALAN ALDA (NARRATION) To look into one of the possible sources
of this invisible Dark Matter, we've come to California and
the first mountain top observatory ever built -- the Lick
Observatory, dating back to 1888. MAN The founder's buried
at the base of the telescope. James Lick was buried at the
base of the pier here.
ALAN ALDA Does anyone ever think about that?
DEBRA FISCHER I used to think about that when I was observing
at the 40-inch down at the end of the hall and in the middle
of the night the wind would come whirring through the hall
and you'd hear the clanking of the old heaters, and yeah,
I was pretty sure he was coming down to visit me.
ALAN ALDA (NARRATION) The original telescope here is still
used to look at the planets in our own solar system. But Debra
Fischer is hunting for planets well beyond its range - in
fact for planets around other stars.
DEBRA FISCHER So this is the little collecting mirror that
we're going to use tonight. The starlight will come down and
hits the mirror and is reflected up through that trough, rslides
up there and goes through that hole in the side of the dome.
Looks like fun, right, we want our photons to have fun. So
the light that we saw, the light-path outside…
ALAN ALDA I love these little mechanical things…
DEBRA FISCHER That's right.
ALAN ALDA Like something from Jules Verne.
DEBRA FISCHER Exactly. The magic part of our whole project
really is this iodide cell. And now as the starlight passes
through the cell, the iodine is absorbing the starlight at
particular wavelengths and so finally in the spectrum of the
star, etched into the spectrum, we have a forest of iodine
lines, thousands of them, and so it's essentially like a grid
on our spectrum.
ALAN ALDA (NARRATION) Debra is looking for tiny telltale
shifts of a star's signature spectrum against that fixed grid
of iodine lines - a shift that betrays a star's moving toward
and away from us due to a planet's tugging at it. The wobble
also reveals the planet's size and orbit.
ALAN ALDA The bigger the wobble of the star, the more it's
doing that, the bigger the planet is going around it, and
the faster it wobbles, the closer it is.
DEBRA FISCHER That's exactly right, yeah.
ALAN ALDA OK, so in that way you can really tell us what's
there.
DEBRA FISCHER That's right.
ALAN ALDA (NARRATION) Debra and her colleagues have found
some 70 of the over 100 planets so far discovered orbiting
other suns. Most of these planets are huge and orbiting fast,
making their detection easier. Debra's team's most dramatic
discovery attracted the attention of a fourth grade class
in Moscow, Idaho.
DEBRA FISCHER And when we found this system, this first star
with three planets, they sent me a letter, you know, "Dear
Dr. Fischer, we've been reading about this discovery in the
newspaper and we're doing scale models of the solar system
with paper plates, but we wondered if you've named the planets
yet, because if you haven't, we have a suggestion." And so
they said the planet that's four times the mass of Jupiter
should be called Fourpiter, and the one that's two times the
mass of Jupiter should be called Twopiter -- of course --
and then the little one that just orbits every four days should
be Dinky.
ALAN ALDA (NARRATION) The star that Debra's observing tonight
she's already looked at some 200 times - and while it used
to be thought an unlikely candidate to have a planet, she's
now picking up the faint trace of a wobble. Planets are thought
to form from discs of dust and gas that surround a sun. And
it could be that many of the billions of stars out there have
planets, so far undetected.
ALAN ALDA The fact that you're looking for planets that so
far haven't been seen mostly, is that some of the missing
matter, or what?
DEBRA FISCHER That's a good question, and one of the early
hypotheses was that maybe the Dark Matter is just planets.
After all, we now believe that planets when they form, some
of those planets fall inward but some are ejected from the
solar system. And the best way to get a handle, sort of a
back of the envelope calculation, is to look at stars that
are forming, being born out of molecular clouds, and to imagine
that all of the material in these typical discs around the
star is ejected. Let's just take that as an approximation.
And then, would that be enough to make up all of the missing
matter. And the answer is no, the calculation has been done,
and that it probably isn't the, it's an order of magnitude,
orders of magnitude, too low, to account for the missing matter.
ALAN ALDA (NARRATION) In fact, not only is most of the missing
matter in the Universe probably not the stuff that stars and
planets are made of - its probably not the stuff that anything
is made of. Here on the Yorkshire coast of northern England
the search for Dark Matter has gone underground. This is the
Boulby Mine, whose mile deep shafts provide cover from something
tantalizing similar to the prime suspect for missing matter.
NIGEL SMITH If you're standing on the surface of Earth, and
you put your hand out, you get hit, one cosmic ray a second
goes through your hand, and that would spoil the detector
signal that we're looking for. So you go deep underground,
and then the large amount of rock between us and the surface
shields us from the cosmic rays. So when we're down in our
labs, rather than one a second going through your hand, it's
one a week.
ALAN ALDA (NARRATION) But while cosmic rays are exotic, at
least they're made from subatomic particles that science is
familiar with. By contrast, the things Nigel Smith is trying
to detect are bizarre even to physicists. Here, a mile down
in a vein of rock salt mined to spread on the winter roads
of northern England, he is in a race with some half dozen
groups set up in similar underground labs around the world
to be the first to detect what are called - with tongue in
cheek -- WIMPs, for Weakly Interacting Massive Particles.
WIMPs have the apparently paradoxical property of being massive
-- in the sense that they exert a gravitational tug - while
being almost completely unable to connect with ordinary matter
in any other way. In fact, to call them "weakly interacting"
is to be generous.
NIGEL SMITH Most of them pass straight through the Earth
and don't even notice. Most of them pass straight through
the sun and don't even notice. But every so often there's
just one or two a month of a year that will actually hit a
nucleus head on, and that nucleus recoils and it's that nuclear
recoil that we're looking for. But the majority of the billions
of WIMPs that are passing through as we stand here every second,
they just stream straight through and you never see them.
ALAN ALDA (NARRATION) This is just one of three different
kinds of detectors here at the United Kingdom's Dark Matter
hunt, and the research project has just constructed an large
new underground facility to house them. There are other detectors
in tunnels beneath the Apennine mountains in Italy, where
a joint Italian-Chinese team has been claiming evidence for
WIMPs - a claim met with skepticism from their competitors…
while in the United States a new facility is being constructed
in a mine in northern Minnesota. All this effort to detect
a hefty ghost particle that may not even exist. For those
involved in the hunt, there's no doubt that it's worth it.
NIGEL SMITH It's a fantastic question. If you're an astronomer
and someone says you don't know what two-thirds of the Universe
is made from, that irritates you, so you want to go out there
and find out what it is.
ALAN ALDA (NARRATION) And astronomers aren't the only ones
in the hunt. Which is why I find myself driving a golf cart
through the longest building in the world, the Stanford linear
accelerator in California. I'm following the track of a subatomic
particle as its accelerated during its two-mile trip to a
speed approaching the speed of light. Eventually the beam
of particles will be divided and spun around a couple of loops
before crashing head on into particles coming in the opposite
direction and smashing into smithereens. We're visiting the
collision point, appropriately, with both a particle physicist
and an astronomer.
ALAN ALDA So the beam of particles will come down here and
go through that pipe?
PERSIS DRELL And then you hope that an electron and a positron
will meet, annihilate, and new particles will be born.
ALAN ALDA (NARRATION) It's from collisions like this that
scientists have built up their picture of the fundamental
particles of matter in what they like to call the Standard
Model. But for the Standard Model to work, physicists have
been forced to invent a strange mirror world, in which the
known particles have ghostly cousins called supersymmetric
particles.
PERSIS DRELL This extra set of particles we haven't discovered
yet, but they're our best candidate, we think it's the smoking
gun, for the Dark Matter out there. So you and I aren't made
of these supersymmetric particles, but the Dark Matter that's
controlling a lot of what's happening in our Universe is made
of these supersymmetric particles.
ALAN ALDA That's the best theory.
PERSIS DRELL That's our best guess at this point.
ALAN ALDA Now this is interesting. You are pretty sure or
are you dead certain that these supersymmetric particles exist
or have existed?
PERSIS DRELL Let Roger…
ROGER BLANDFORD Less than pretty sure but if this were a
horse race this is the one I'd be putting my money on.
ALAN ALDA Is it thought that supersymmetric particles are
all over the Universe?
PERSIS DRELL They're out there…
ALAN ALDA And how did they get started? Where did they come
from?
PERSIS DRELL From the Big Bang itself.
ALAN ALDA From the Big Bang. So are you trying to create
a situation something like the Big Bang where you get both
the particles and the supersymmetric particles, the mirror
versions of them? I thought you needed something a lot… I
thought you needed a lot more energy than you could possible
get on Earth to create a Big Bang.
PERSIS DRELL We're not recreating the Big Bang.
ALAN ALDA Right, thank God, because I'd stand a lot further
away from it and I'd wear that hat.
PERSIS DRELL But we are able, if we have enough energy in
our particle accelerators to create the constituents that
were created in the Big Bang.
ALAN ALDA (NARRATION) And so at the same time as astronomers
are going underground in their hunt for the missing Dark Matter,
particle physicists too are burrowing to build the biggest
atom smasher ever in the hope of creating Dark Matter. This
is the construction of what's called the Large Hadron Collider
at CERN in Switzerland. Due to come on line in 2007, the LHC
will have gigantic detectors designed to peer into the wreckage
of particle collisions of truly stupendous energies - if not
quite the Big Bang, then certainly the closest we've ever
been to it. The closest we've actually been to it, of course,
was with the WMAP spacecraft, which mapped the ripples left
as the Big Bang cooled. In the pattern of these ripples, the
WMAP scientists see direct evidence for Dark Matter.
MAX TEGMARK You only get this if you have about six times
more Dark Matter than all atoms combined.
CHUCK BENNETT What we did was we generated literally tens
of millions of possible Universes on the computer and we compared
them with our measurement of the real Universe that we have.
And I think of it like matching fingerprints. So this is the
actual fingerprint of the real suspect and we have a mug-book
of fingerprints and we match 'em up and we pick out the right
suspect that way. And as Max described, the right suspect
has this substantial amount of Dark Matter in it.
ALAN ALDA (NARRATION) Today, then, the evidence is mounting
that most of the stuff in the Universe is not only invisible
to us but isn't even what the visible stuff is made of. But
to astronomers like Alan Dressler, looking back in time to
see how the Universe began, Dark Matter is more than just
astonishing; it allowed us to be.
ALAN ALDA So you're taking this picture of way back in time
and you're seeing the formation of the stars. What role does
Dark Matter play in that?
ALAN DRESSLER It's very important to see how galaxies form
but they couldn't have formed we now believe without the Dark
Matter. Because there wasn't enough gravity in all this kind
of material that we're made of to coalesce and make stars.
And that's where the Dark Matter played the pivotal role.
It actually held this, what we call baryonic, normal matter
together and allowed it to begin to concentrate and to cool
and then make stars. So already there were those sort of wells,
these places where gravity was strong… And all these atoms
suddenly said, oh, there's gravity here from this Dark Matter,
and they headed in that direction. So they fell into those
little wells of gravity that had been growing since the Big
Bang.
ALAN ALDA (NARRATION) But if Dark Matter's gravitational
hug was indispensable to our Universe's birth, we now know
that from the start it's been opposed by an anti-gravity force
that might - if things had turned out just a little bit differently
- have overwhelmed it, and instead blown the infant Universe
apart. That story next.
Dark Energy
ALAN ALDA (NARRATION) In the early 1990s, two groups of astronomers
came up with a new idea for discovering the ultimate fate
of the Universe. Both groups - which were soon to become rivals
- used several telescopes in their quest, including this one
at Cerro Tololo in Chile.
CHRIS SMITH They have their nights on the telescope, sometimes
actually immediately after our nights, or in between our nights.
ALAN ALDA So do you go around looking for scraps of paper
the other one's left, or what?
CHRIS SMITH No, sometimes we look at, you know we try to
figure out what they've observed, but usually it's a friendly
rivalry.
ALAN ALDA (NARRATION) Both teams used the telescope to look
for the same thing - the death of a star. But not just any
stellar death - a particular kind caused when a companion
star dumps material onto a so-called white dwarf, until the
white dwarf reaches a critical mass and explodes. This is
called a Type 1a Supernova - and the astronomers like it because
all Type 1a Supernovae are almost exactly alike -- identical
flashbulbs popping off randomly all over the sky.
NICK SUNTZEFF With just a two-minute exposure on this telescope,
we can see half way across the Universe. That's how powerful
the telescopes are and how bright supernovae are. So we can
take very short exposures and cover large parts of the sky
to discover supernovae.
ALAN ALDA (NARRATION) But discovering them is only the beginning.
Once a supernova is spotted, other even bigger telescopes
are standing by to pounce on its light and read its spectrum.
NICK SUNTZEFF If we don't find supernovae in this telescope,
then all the other telescopes who are waiting have nothing
to do. They get real mad at us.
ALAN ALDA Is this the first night you're observing in this
test?
NICK SUNTZEFF Yeah, this is the beginning of our season,
so we're going to go three months now, thirty half nights
searching for supernovae. And tonight is the first night.
ALAN ALDA So your exposure is covering all of this and that's
even more than a full moon would be in the sky. So what's
the probability that you'll find a supernova?
NICK SUNTZEFF In this one field?
ALAN ALDA Yes.
NICK SUNTZEFF It's about one.
CHRIS SMITH It's one for the month.
ALAN ALDA So sometime during this month you're going to,
if you keep pointing there, you're going to catch at least
one.
NICK SUNTZEFF Oh, yes, definitely.
CHRIS SMITH Now the telescope is slewing so stars are whipping
by.
NICK SUNTZEFF Here's a cool image. This is the first image
that came off tonight. And so you can see lots of galaxies.
Very faint galaxies, stars. There's a very nice spiral galaxy
here with distorted arms. So you're going to observe, right?
ALAN ALDA You mean, more than I am now?
NICK SUNTZEFF Yes, right here.
ALAN ALDA You want me to actually…
NICK SUNTZEFF Sit here, yes.
ALAN ALDA The end of science as we know it. All right. OK.
Well now, let's see, I'll just hit a few keys.
NICK SUNTZEFF No!
ALAN ALDA I just like to poke around, that's how I learn,
you know. What should I do first?
CHRIS SMITH When he says OK, you hit enter.
ALAN ALDA And that's it?
CHRIS SMITH That's it, yes. OPERATOR OK.
ALAN ALDA OK
CHRIS SMITH And that sound was the shutter opening.
ALAN ALDA Oh yeah, I heard that.
NICK SUNTZEFF Your first image in search of supernovae.
ALAN ALDA I hope I find one.
ALAN ALDA (NARRATION) That first night of the season, Nick
and Chris and their team took 16 different snapshots of the
sky. By the next night, now no longer observing from the telescope
but from a control room in the nearby town, they had processed
several of those images. And one of them - though sadly not
mine - came up trumps. GAIUS So here we've got a big diffuse
source of light. And in both the images there's apparently
a new light source just outside that galaxy. That looks like
a supernova to me.
NICK SUNTZEFF Yeah, great. This would be a really good candidate
if we get a follow-up image to do spectroscopy. As a matter
of fact, we don't need a follow-up image. This definitely
is a supernova.
ALAN ALDA (NARRATION) Supernovae are very rare events. The
last one in our galaxy was 300 years ago. So it's only by
staring at tens of thousands of galaxies at a time that the
supernova hunters can hope for success. Once they've found
one, then there are a few days while its explosion continues
for a large telescope like the Keck in Hawaii to get its spectrum.
This not only confirms it's a Type 1a, but also gives its
age: the older the light, the more it's been stretched as
space itself has expanded, and so the longer its wavelength
-- the more it is shifted toward the red. And because every
Type 1a supernova explodes like a standard flashbulb, its
brightness reveals how far away it is. And this is why both
rival teams of astronomers were hunting so eagerly for Type
1a Supernovae: by finding them of different ages and measuring
their distance, both groups hoped to find the answer to one
of astronomy's great questions: what is the ultimate fate
of the Universe? We met members of one team at Cerro Tololo.
The other is based here in at the Lawrence Berkeley Laboratory
in California, and is led by Saul Perlmutter. Both teams expected
to measure how much the expansion of the Universe has been
slowing due to gravity - especially the gravity of all that
recently discovered Dark Matter.
SAUL PERLMUTTER We thought it was going to be a great project.
We were going to find out whether the Universe was going to
last forever or not, or whether some day all this stuff in
the Universe, all the matter in the Universe, would slow the
expansion down to the point where it would come to a halt
and then collapse. And what we ended up with, when we started
looking at the data, it looked like it was very little matter
in the Universe, in fact it wasn't slowing very much at all.
And then as you really looked at the data you started noticing,
oh, it's not only not slowing down much at all, it's not even
slowing, it's actually speeding up. And that was a real shock,
because it was not part of the original, you know, description
of our project when we were applying to use the telescopes.
It was way better than that.
ALAN ALDA (NARRATION) Instead of slowing down due to gravity,
the expansion of the Universe appeared to be speeding up as
if under the influence of some sort of anti-gravity. The rival
team was coming to the same mind-boggling conclusion.
ALAN ALDA Was it an exciting moment of was it just puzzling?
CHRIS SMITH Puzzling and concerning, because it wasn't the
expected result. We were expecting deceleration. So really
the knot twists up in your stomach saying, OK, let's go back
and do this again and make sure this is right. And you go
back through the numbers once again, and you go back through
the numbers yet again and now you're starting to believe,
well, we're on to something here. Wow! And the whole group
- we're distributed and so the emails start coming in, saying,
jeez, can this be right?
SAUL PERLMUTTER You don't want to come out with anything
that's wrong, of course, in a scientific, you know, a major
scientific announcement, and so you're being so careful trying
to check, well maybe it's this, maybe it's that, you're looking
at every possible thing. Finally we came to the conclusion,
well, we have to come out and say it.
ALAN ALDA Were you all getting it at around the same time?
NICK SUNZTEFF Yeah, we announced at the same time in 1998
at a conference in Santa Barbara, and both groups came out
and we sort of knew that the other team was going to announce
the same thing, and I'm never sure how we knew that.
ALAN ALDA Were you pointing your telescope in their window
and looking at their paper?
NICK SUNZTEFF No, we wouldn't do that!
SAUL PERLMUTTER The fact that both teams got the same result
I think gave people a lot of confidence that it wasn't just
some mistake somebody had made in their calculations, because
they knew that the two teams would have loved to, you know,
been able to get the right answer and show the other one might
be wrong.
ALAN ALDA (NARRATION) Not everyone was taken aback by the
idea of a runaway Universe. Michael Turner had actually predicted
the possibility several years earlier, reviving an old idea
of none other than Albert Einstein. Turner came up with a
name for a force that could push the Universe apart - Dark
Energy -- but its roots lay in one of Einstein's famous equations.
ALAN ALDA The notion of Dark Energy was, as I understand
it, something that he came up with and didn't really understand
he'd come up with it. How far off am I with that?
MICHAEL TURNER That catches a lot of it. I mean, in science,
people are often confused and so Einstein was confused about
the expansion of the Universe. His equations wanted a Universe
that expanded and so he put in this fudge factor that canceled
the attractive gravity of matter.
ALAN ALDA (NARRATION) When just a few years later the Universe
was discovered actually to be expanding, the Cosmological
Constant - Einstein's anti-gravity fudge factor - was no longer
needed. He gratefully discarded it, calling it his greatest
blunder.
MICHAEL TURNER But one of the wonderful things about science
is that when we're in this struggle to try to understand,
we invent things. And once you take something out of Pandora's
Box, you can't put it back. And so this idea was laying around
in our idea box and it's sort of like anti-gravity, it's a
repulsive gravity, and so it resurfaced again in trying to
understand why the Universe, not is expanding, but the expansion
is speeding up.
ALAN ALDA How did you come up with the name Dark Energy?
MICHAEL TURNER It's kind of a nice yin and yang with the
Dark Matter. You know, so we have Dark Matter and we have
Dark Energy and they're fundamentally different - you know,
matter is different than energy - and then today we have the
battle between the Dark Matter and the Dark Energy.
ALAN ALDA (NARRATION) There is one uniquely privileged spectator
to the battle between Dark Matter and Dark Energy - the Hubble
Space Telescope. Perched high above the atmosphere of Earth,
it has a clear view of the supernova beacons used to track
the Universe's history. We went to visit the control room
for the Hubble Space Telescope in Baltimore.
ADAM RIESS Welcome to the Space Telescope Science Institute.
ALAN ALDA (NARRATION) My guide is supernova hunter Adam Riess.
ALAN ALDA Can you tell me what all these folks in here are
doing? I mean, there's constant activity and chatter. What
is it all about?
ADAM RIESS Right. They're primarily monitoring health and
safety. They're looking at telemetry. They're looking at temperatures
and voltages of thousands of different components pf the telescope
to make sure they're all within tolerances. They're looking
at heating on one side of the telescope when it's in the sun
side. About once a week we upload a whole week's worth of
observations, what's supposed to be done that week with the
telescope. So if we find a supernova, for example, we usually
have to find it by Tuesday, because Tuesday is a special day
when they build the calendar for the next week. It's sort
of funny. The light's been traveling for 11 billion years
and it finally arrives and it's got to arrive on Tuesday.
ALAN ALDA (NARRATION) In March 2002, the space shuttle Columbia
- on what was to turn out to be its last completed mission
- installed a new camera on the Hubble, the Advanced Camera
for Surveys.
ADAM RIESS This camera is much more sensitive to light, and
it has more area, so I have a better chance of finding a supernova
every time I pick an image in the sky.
ALAN ALDA (NARRATION) Adam's plan was to look back with the
new camera to supernovae exploding when the Universe was young.
He found some half dozen, ranging in age back to 11 billion
years ago. His hope was to find out if the Universe has always
been pushed apart by Dark Energy, or if once it had been reined
in by the gravitational pull of Dark Matter. Adam Riess works
closely with Mario Livio. Adam observes the Universe, Mario
comes up with theories about it.
MARIO LIVIO Basically, you have the Universe behaving something
like this. At first, it is expanding against gravity. So think
of it as being held back by some sort of spring…
ALAN ALDA But it's getting bigger and bigger and bigger over
millions, billions of years…
ADAM RIESS That's right.
ALAN ALDA And then at some point it's…
ADAM RIESS About five billion years ago, we think…
ALAN ALDA It stops slowing down, and instead of collapsing
- that's what we would expect, it would get that big and then
come back, right?
MARIO LIVIO Well, maybe not come back, but it would go slower
and slower and slower. Instead, it suddenly starts going faster
and faster and faster.
ALAN ALDA And you found out when it started going faster
and faster and faster?
ADAM RIESS That's right. We actually witnessed the transition
from the more recent accelerating expansion to the earlier
slowing expansion.
ALAN ALDA (NARRATION) This literal turning point in the history
of the Universe came at about five billion years ago, when
Dark Matter began losing its gravitational pull against Dark
Energy's inexorable push.
MARIO LIVIO You know, gravity increases in proportion to
distance. You know if you double the distance, gravity becomes
four times weaker. This force that you get from Dark Energy,
when you double the distance the force becomes twice larger.
ALAN ALDA Oi, oi, oi!
ADAM RIESS We think it's a property, actually of the vacuum.
So when there's more vacuum between you and a distant galaxy,
there's more of this Dark Energy.
ALAN ALDA So there is a factor of an increase in the amount
of Dark Energy that has a factor on speed?
ADAM RIESS Yes, that's right. It's a little bit like a built-in
spring in the vacuum, and as something gets further away,
there are more and more of these springs connected and it's
harder to compress. In fact, they're pushing more and more.
And so the bigger the Universe gets, Dark Matter is losing
its pull on the Universe, Dark Energy is gaining its push.
ALAN ALDA It's always been there, right?
ALAN ALDA (NARRATION) The question that's now obsessing astronomers
- including Michael Turner - is what Dark Energy might be.
MICHAEL TURNER We just don't know what it is. If it is like
Einstein's' Cosmological Constant, then it's just the energy
of nothing. And according to quantum mechanics, nothing is
not nothing, it's full of particles that are living on borrowed
time and borrowed energy.
ALAN ALDA That pop into existence…
MICHAEL TURNER Pop into existence and then when the accountants
come along, they disappear. And so, if it's the energy of
nothing, it's always been here, and then we're in for a very
tough bit of history in the future because the Universe will
keep speeding up and speeding up and speeding up and things
will get farther and farther away and instead of the beautiful
sky we have today with billions of galaxies, we'll only see
a couple. It could be that it's just a phase we're going through,
that something's out of whack and that the Dark Energy will
dissipate. I think what you're starting to see is that we
don't know much about it at all.
ALAN ALDA All this stuff didn't fill us in that much.
MICHAEL TURNER We need some help, we need some help.
ALAN ALDA (NARRATION) Help may be on the way from a proposed
new spacecraft expressly designed for supernova hunting. With
a camera able to image thousands of supernovae at a time,
the SNAP satellite would hugely increase the number of beacons
out there measuring the Universe's expansion. This might not
only help find out what Dark Energy is, but also help answer
what is perhaps the deepest question of all. Is there a reason
why the Universe turns out to be in almost perfect balance
between the pull of Dark Matter and the push of Dark Energy?
Or is the fact that Dark Energy didn't blow it apart in its
infancy just a lucky accident? Maybe the Big Bang that turned
out so well for us was just one big bang among many.
MICHAEL TURNER If this burst of expansion happened here,
there's no reason it wouldn't have happened here and there,
and in that past and in the future.
ALAN ALDA In the same Universe?
MICHAEL TURNER In the same Universe.
ALAN ALDA In what was, what should amount…
MICHAEL TURNER So now we need new language, right? So the
Universe is a whole ball of wax, but there are different disconnected
parts in it.
ALAN ALDA It's like bubbles in a glass of champagne.
MICHAEL TURNER Exactly.
ALAN ALDA The champagne is the Universe at any given time,
or the multiverse, and each bubble is a new Universe.
MICHAEL TURNER Is a new Universe.
ALAN ALDA If this is our Universe, where would the other
Universes be in this multiverse?
MAX TEGMARK Thanks for passing me the Universe. We're actually
kind of sloppy in astronomy when we talk about the Universe.
What we usually mean is just the interior of this beach ball.
CHUCK BENNETT The part of the Universe that we can observe,
we call the Universe.
MAX TEGMARK And that's of course, strictly speaking, not
true at all, because I don't have a single colleague who would
entertain that space ends here, you know, there's a sign here
saying "space ends here, mind the gap." We all believe that
space goes on outside, right?
ALAN ALDA Yes.
MAX TEGMARK And most of us believe that space actually goes
on forever, it's infinite. Which means there's another sphere
like this and in the middle of that maybe there's another
planet where people discuss their Universe and can't see ours,
and there's probably infinitely many of these.
MARIO LIVIO If you have this ensemble of universes, there
may be some basic things which are true for all of them, but
there may be some quantities which are accidental in these
different universes Some of those universes will allow life
to evolve and us to be here and speak about it, and some won't.
ALAN ALDA (NARRATION) We said at the outset that our Universe
just got a whole lot weirder, dominated by matter we can't
see and a force we can't feel. But maybe it's even weirder
than that. Not only are we not at the center of our Universe;
we are not even in the only universe, just one in which Dark
Matter and Dark Energy fought each other - at least when it
mattered, back when the stuff we're made of was created -
to a standstill.
