NARRATOR: Does our sun
have a deadly nemesis that dooms life on our planet? [explosion] Is it possible to
travel through time? That is one of the
greatest questions. NARRATOR: What happened
to matter's evil twin? The mind hunts
for an explanation. NARRATOR: How did the
water on Mars disappear? And what came
before the Big Bang? This is the greatest
mystery in all of science. NARRATOR: Big questions
and cutting-edge science The Universe,
Unexplained Mysteries. [dramatic music] Among the unexplained
mysteries in the universe, one has a particular
urgency for those of us who enjoy living
on planet Earth. Do earthlings have a
regularly scheduled date with extinction once
every 26 million years? And if so, what causes
this periodic hard reign of destruction? RICHARD MULLER: You have
this enormous explosion. Anything within thousands
of miles will be killed. You're talking here, first,
the blast wave of a tsunami. You're talking about
the enormous heat, fires all around the
globe, and then darkness. NARRATOR: For millions of years,
enormous objects from space have slammed into Earth
with disastrous results. One impact in the waters
of the Yucatan Peninsula is blamed for the
extinction of the dinosaurs 65 million years ago. But this wasn't the first
mass extinction on Earth, and it probably
won't be the last. And it wasn't the biggest mass
extinction event of all time, because that one was the
permian extinction in which 95% of the species in the
oceans died and about 80% of those on land. So radical extinction
events have happened. NARRATOR: Some
scientists believe these periods of
death and destruction happen like clockwork. RICHARD MULLER:
Some paleontologists found a very strange pattern. What they found were the great
extinctions such as the ones that killed the dinosaurs. But others, too, didn't
happen at random times, but seemed to occur on
a regular time schedule. That was very strange. They were disappearing
every 26 million years. It was begging for
an explanation. NARRATOR: Astrophysicist
Richard Muller believes the explanation for
this periodic destruction is a dim red dwarf star
lurking on the edge of the solar system, a star
that he fittingly calls Nemesis. According to his theory, Nemesis
is an undiscovered companion star to our own sun. [dramatic music] It travels between one
and three light years from the center of
the solar system on an elongated,
elliptical orbit. As Nemesis makes its closest
approach to the sun every 26 million years, its orbit takes
it right through the Oort cloud, a collection of
an estimated trillion comets surrounding
our solar system. That's when the order
of the solar system turns especially chaotic. RICHARD MULLER:
When that happens, Nemesis gets close to the
comets and perturbs their orbit. NARRATOR: According
to Muller's theory, the gravitational
disruption caused by the small, innocuous star
causes long, undisturbed comets to break away from their
orbits in the Oort cloud. Pulled towards the
sun by its gravity, a billion comets
are sent careening toward the inner solar system. A handful inevitably cross
paths with the Earth, resulting in massive impacts
and mass extinctions. The claim that our sun has an
undiscovered companion death star is controversial. Most scientists believe that
the sun is a solitary star with no companions. But in the universe, binary
or even triplet stars grouped together by
gravity are the norm. ADRIENNE COOL: The majority
of stars in our galaxy are parts of either
binary or triple stars. And so the idea that
the sun conceivably could be part of a binary isn't
crazy from that point of view at all. It's an interesting question. NARRATOR: Even if the
sun could conceivably have a binary companion,
astronomers have never observed a binary system in
which the pair of stars are as far apart as
Muller claims our sun and Nemesis would be. Muller needed proof
that Nemesis was real. In 1997, a NASA mission
began that had the potential to shed light on the mystery. The Two Micron All-Sky
Survey, or 2MASS, used twin infrared telescopes
to scour the universe for previously unknown stars. 2MASS specialized in
hard-to-find bodies in and near our
galaxy, and to date, has produced over
two million images. If Nemesis was out there,
2MASS should have spotted it. But the survey never
detected anything fitting the description of
Muller's death star. MICHIO KAKU: We've looked. We've looked real hard for
death star, for Nemesis. And we can't find it anywhere. NARRATOR: But Muller
isn't surprised 2MASS didn't find his Nemesis. RICHARD MULLER: The reason
is, at a distance of about one light year, which is the
distance it would have in order to have a 26 million year orbit,
its motion is very little. And so it would have been missed
by the standard surveys that look for nearby stars. NARRATOR: Another possibility
is that Nemesis may actually be a brown dwarf. These failed stars are much
smaller than red dwarfs. And with a highly
elliptical orbit, a brown dwarf would remain far
from earth most of the time, and out of the watchful
eye of astronomers. If that's the case, Nemesis
could have easily slipped under the 2MASS radar. [dramatic music] Richard Muller vows
to continue looking and plan as yet another
more detailed study. He believes it's
only a matter of time before Nemesis is found. RICHARD MULLER: There are
lots of stars out there. There are millions of them. But when you find a needle in
a haystack, you can look at it and say, well, that's not hay. Similar with this. When we find Nemesis,
we'll measure the orbit and we'll prove
that it's Nemesis. [dramatic music] NARRATOR: Of all the unexplained
mysteries in our universe, perhaps the most tantalizing
and controversial is whether it's possible
to travel through time. Can we really travel
back into the past? Can we really alter our destiny? It is one of the
greatest questions. NARRATOR: In 1965, Ron
Mallett was only 10 years old when his father died
of a heart attack. Grief stricken, young
Mallett yearned for a way he could see his father again
and perhaps save his life. RONALD MALLETT: About
a year after he died, I came across HG Wells's
book The Time Machine. And that is what saved me
because I thought, if I could build a time machine, as
HG Wells talked about, that I could go back into the
past and try to save his life and see him again. And so I became obsessed
with the notion of trying to build a time machine. [suspenseful music] Gentlemen, I am talking
about traveling through time. NARRATOR: The Time Machine
was a work of fiction. But Mallett soon
discovered there was science to support the
mysterious notion of time travel. And the source was none
other than Albert Einstein. Einstein theorized that
space and time were linked so that one could imagine
space-time as a sort of fabric or sheet. With his general
theory of relativity, Einstein showed that a massive
object like a planet, a star, or a black hole, actually warps
the fabric of space and time. In fact, Einstein believed
that gravity, the force that binds us to the earth and
keeps the earth in orbit around the sun, is really just
an effect of this warping. For Mallett, this mind
and universe bending idea has far-reaching implications. Because if you could generate
enough gravity to twist time into a loop, perhaps you
could create a pathway for moving backwards and
forwards through time. Einstein's theories
fueled Ron Mallett's quest to learn how to build
his own time machine. But time travel
wasn't a subject that could be studied by serious
scientists out in the open. RONALD MALLETT: As
a matter of fact, I used a cover story
that worked for me. I study black holes. Because black holes allow
me to understand how Einstein's theory affected time. And it was a crazy idea,
but it was considered legitimate crazy. So I built my career on
studying that and being able to use Einstein's
general Theory of Relativity. NARRATOR: Black holes,
the massive remnants of collapsed stars,
have an almost unmatched gravitational power to
distort space and time, which is exactly what
Mallett wanted to do. But how could he create in
the laboratory something jam-packed with enough matter
to actually warp space-time? For inspiration, Mallett
again to Einstein and his most famous equation,
E equals MC squared, which showed that matter and
energy are just different forms of the same thing. So following Einstein's
theory, light, which is energy, should be able to
warp space and time just like a massive object does. RONALD MALLETT: We're used
to the notion that gravity is created by matter. But it turns out that
in Einstein's theory, light can create gravity. And that is what my
work is based on. In other words, if gravity
can affect time and light can create gravity, then
light can affect time. [mysterious music] NARRATOR: Mallett
has built a model to demonstrate his concept that
a circulating laser beam can create a tunnel of light
that twists space and time. RONALD MALLETT: It has four
intersecting laser beams. The region within
that column of light would represent the region in
which space is being twisted. And eventually, time
would also get twisted by this column of light. [mysterious music] And this would allow us to
travel back into the past. NARRATOR: The
first time traveler will have to be
something much smaller than a human being, a subatomic
particle like a neutron. What we're trying to
do is not human beings, but to try to send subatomic
particles and information to that. And that is a huge leap in
itself, because imagine, if we can send information back
into the past that could tell us about future disasters and be
able to avert those disasters. We can understand how a
circulating light beam can twist space and time by a simple
analogy with a cup of coffee. We think of the coffee in the
cup as being like empty space and we think of the spoon as
being like a circulating light beam. And you can see what happens
to the coffee as I stir. The coffee swirls around. Well, that's what the
circulating light beam is doing to empty space. And we can see the
effect of this, in the case of the coffee,
by putting in a coffee bean. As I swirl around, the coffee
bean gets swirled around. In the case of the laser,
as the beam is circulating, we put a subatomic particle
called a neutron in. And as we stir the space
around, the neutron will get swirled around
just like the coffee bean. Now remember, in
Einstein's theory, space and time are connected. So that swirling of space will
cause the straight line of time to be swirled into a loop. And along that loop in time,
we can go from the past to the present to the future,
and then back into the past. NARRATOR: Science fiction
has depicted time machines as allowing unrestrained travel
forward and backwards in time. But Mallett cautions that a
time traveler could only journey back as far as the moment that
the time machine was first turned on. In other words, if I
turned the device on today and I leave it on for 100 years,
then someone 100 years from now could travel back 75 years, 50
years, 25 years, all the way back to the moment I
turned the device on. But they can't travel earlier
than that because the device didn't exist earlier than that. And it's the device that's
creating the effect. So there's nothing for
them to time travel-- to materialize into. NARRATOR: This limitation means
that Mallett's time machine could never give
him the capability to travel back to 1955 to
save his father's life. To do that would
take some technology from out of this world. Theoretically, an advanced
alien civilization might have a time machine
that was switched on thousands of years ago. RONALD MALLETT: We may be able
to use their time travel to go back to visit our ancient past. Because if they have developed
time travel, let's say, 10,000 years ago, it would
still have the same limitation. But once we encounter
them, we could use it to-- perhaps someday, we may
be able to visit ancient Egypt and ancient Rome. NARRATOR: For now, Mallett is
focused on getting his time machine built, a project
that will require a quarter of a million dollars
in startup costs alone. Money is just one obstacle
facing any physicist daring to dabble in time travel. There are also certain
paradoxes that many believe make time travel impossible,
like the infamous grandfather paradox. Imagine you go back in time
and kill your own grandfather before he meets
your grandmother. Therefore, you never
would have been born and therefore, couldn't
have gone back in time in the first place. And then a loop is setup
of possible, impossible, happened to didn't happen. NARRATOR: But Mallett
believes recent advances in theoretical physics suggest
that these paradoxes aren't a problem at all. Many physicists now believe
in the far out notion that our universe is just one
of many parallel universes, so that when you
go back in time, you might actually be entering
a parallel universe in which you can alter events without
affecting the universe you came from. We believe that
the river of time can have whirlpools, whirlpools
by which you may be able to go back and meet your parents
before you're born or perhaps even fork into two rivers by
which you can actually alter the past to create an
alternate universe. These are all theories that
are at the very forefront of modern physics today. NARRATOR: Mallett believes we
may be as little as a century away from time travel
by humans, still too late for him to travel back
in time to save his father. CUSTOMER: Ronald,
nice to meet you. Thank you. Remember what's
happening in space. It's swirling around. NARRATOR: But his
personal loss has opened the door for a new
world for future generations. I developed the basic
equations for this. It has led to my being able to
share something with the world that I would never have
been able to share before. And I feel that is actually a
fitting memorial to my father, that I've been able to do that. I feel very good about that. [suspenseful music] NARRATOR: As the universe
was first forming, scientists believe
it was comprised of more than just the regular
matter that now makes up everything around us. They believe it had an almost
equal amount of antimatter, matter's elusive, evil twin. ADRIENNE COOL: If you go back
to the very early universe, it turns out that it was made
of matter and antimatter. It turns out that every
particle has an antiparticle. And it sounds kind of
crazy, but it's real. It's of sci-fi, you
know, antimatter. But what is this
mysterious antimatter? And where did all of it go? RONALD MALLETT: Antimatter
is exactly like matter. The difference
between it is the fact that it has completely different
charge associated with it. NARRATOR: Regular matter is made
of atoms, which in turn, are made of subatomic particles like
negatively-charged electrons and positively-charged protons. Antimatter are the opposite
of these particles. They have the same mass but
the opposite electrical charge. Protons are
positively-charged particle, and it's the
nucleus of the atom. The antiproton would be a
negatively-charged proton that has exactly the same mass. NARRATOR: In our universe,
opposites attract and particles and antiparticles
are pulled together. One would think this
is a relationship made for the heavens. But every time matter comes
in contact with antimatter, the outcome is the same. They annihilate each other. Imagine two space ships hurtling
through space on a collision course. One is made of regular
matter, and the other is an antimatter craft built
by an alien civilization. The impact would be spectacular,
and there would be no wreckage left behind for cosmic crash
investigators to examine. ADRIENNE COOL: The matter
and the antimatter disappear. Poof, they're gone. But the energy
doesn't disappear. The energy reemerges in the
form of two very energetic gamma rays, photons. And the amount of energy locked
up in a tiny amount of mass is quite astonishing. If you take matter and
antimatter and combine it, it is explosive. And in fact, it is one of the
greatest sources of energy in the universe, the collision
of matter and antimatter. So if I were you, I would not
put antimatter in your pocket, if you know it's good for you. NARRATOR: Volatile as antimatter
is when it meets matter, there's a tremendous
energy potential if we knew how to harness it. So to get an idea of how much
energy is locked up in matter, if you imagine for a minute that
these two piles of sand are-- that one is matter
and one is antimatter. And you let them
come together, they would annihilate
and produce energy. How much energy? Enough energy to power all
of California for a week, just in those two piles of sand. NARRATOR: The biggest mystery
surrounding antimatter is this. If there were nearly
equal amounts of matter and antimatter in
the early universe, then where is all
the antimatter now? MICHIO KAKU: One of the great
mysteries of the universe is, what happened to our
evil twin, antimatter? Everywhere we look
in the heavens, we see ordinary matter. We don't see antimatter. There's only a small amount
of antimatter coming out of the center of the
Milky Way Galaxy. KIM STANLEY ROBINSON:
Why this universe appears to be made entirely
of matter and there isn't much antimatter to be
seen out there is a mystery. I don't think it'll ever
be explained anyway. But the mind hunts
for an explanation. NARRATOR: One possibility
is that perhaps, there was a slightly higher
percentage of matter than antimatter in
the early universe. So as the particles and
antiparticles collided in a war of annihilation, that
small percentage of matter survived, the last living
veterans of our most ancient battlefield. For every billion
antiprotons, you need a billion and one protons. Then a billion all annihilate. And you're left with
that one proton. MICHIO KAKU: And
the leftover is us. We are the residue. We are the leftover of this
titanic blast of energy released by the collision
of matter and antimatter at the instant of time. [gentle music] Our most advanced theories
cannot explain why there was this asymmetry between
matter and antimatter. But thank god, it exists. Otherwise, we wouldn't be here. NARRATOR: But even though matter
prevailed to make up everything we see around us, could
there be distant galaxies or regions of space where
antimatter still reigns supreme? KIM STANLEY ROBINSON: It may be
that there are entire galaxies that are just 99.9% antimatter,
just like this one's matter. And if an antimatter galaxy were
to run into a matter galaxy, then they both
would be annihilated in some stupendous flash
of light and power. NARRATOR: As strange
as it is, scientists have learned how to create
minute quantities of antimatter in laboratory accelerators
for medical purposes. Particles of antimatter from
decaying radioactive material are injected into the body to
create PET scans of the brain. Many people don't realize that
when they go to the hospital and have a PET scan, they're
actually being injected with a source of antimatter. The P in PET corresponds
to positrons. Positrons are antielectrons. ADRIENNE COOL: And it goes
to some part of the body that they're trying to
figure out what's going on. And then when the
positron's emitted, it finds an electron very
quickly, annihilates with it, and the gamma rays come out
of the body and are detected. MICHIO KAKU: It concentrates
in the parts of the brain where there's mental activity. And then we can detect the
emission of positron radiation. So this allows brain scans to
give us gorgeous photographs of the thinking brain, made
possible by antimatter. NARRATOR: While
antimatter has helped to unlock the secrets
of the human brain, the human brain has yet
to unlock all the secrets of antimatter. ADRIENNE COOL: We do not
know why the universe is made of matter now. But we are making
progress towards answering that question, you know,
little steps at a time. NARRATOR: Like many mysteries
in our ever-changing universe, the truth about antimatter may
remain for now in the realm of the unexplained. [suspenseful music] Mars and mystery have
always gone hand-in-hand. But the most intriguing
mystery of the Red Planet has nothing to do
with alien invaders. Scientific evidence
suggests that Mars was once a more earth-like planet,
with one of the key elements to support life, water. PETER SMITH: Water existed
in abundance on Mars. We find the evidence
of old flows. We see a tiny bit of water
vapor in the atmosphere. NARRATOR: There are
even features on Mars that look like old river
valleys and floodplains. It was once a tropical
planet with oceans and seas. But all that water disappeared. NARRATOR: How could
all the water on Mars have simply vanished? And why did it disappear? These are mysteries that
scientists are struggling to solve. Geologic evidence gathered by
the Mars rovers and orbiters suggest that 3.5 billion years
ago, Mars's watery surface changed dramatically. The once temperate planet
became a cold, dry place, and the water vanished. But figuring out when
the water disappeared doesn't tell you
where it went or why. PETER SMITH: The water on Mars
was lost a very, very, very long time ago. And I'm talking
billions of years. And the clues that would
lead you to know where that water went are long gone. NARRATOR: A series
of events on Mars appears to have drastically
changed the watery landscape. Mars endured an intense period
of volcanism that spewed lava across the surface. When it finally ended, the
planet's molten iron core solidified. This may have been what caused
Mars to lose its magnetic field and protective ozone layer. This left the atmosphere
vulnerable for the solar wind from our sun, which
is quite powerful. NARRATOR: Solar winds
pummeled the planet for millions of years, stripping
any remaining atmosphere. Now, water vapor that
once fell as snow or rain escape the planet's small
gravitational field. PETER SMITH: So water is brought
up into the atmosphere as water vapor. And it's bombarded by
ultraviolet radiation, which can split water, which is
H2O, into hydrogen and oxygen. And the hydrogen, being
the lightest gas known, floats up to the top
of the atmosphere and can get swept away
by the solar winds. [dramatic music] NARRATOR: Another theory
for the loss of Mars's water involves a threat from
outside the planet. There is evidence that
in the early years of the solar system, Mars
resided in a deadly flight path. PETER SMITH: There was one
cluster about 3.9 billion years ago called The Great Bombardment
that really must have peppered that planet with
many, many impacts. And that kind of an event would
have actually thrown material and atmosphere right off
of the planet and outside of the gravitational field. Let's imagine that we
have an asteroid here. And this asteroid is really
the size of a mountain. And imagine this is tumbling
through space at a very high speed, and we're talking tens
of thousands of miles per hour. If we come zipping in
at a high speed, splat. It's lost to space. Much of it will sink in. Some will become atmospheric
gases, sputtered away to space. Some will be lost. NARRATOR: Other
answers to the mystery of Mars's disappearing water may
be hidden deep inside the Red Planet. Some of the water combined
with carbon dioxide to form polar icecaps up to
two miles deep and a permafrost that covers much of the surface. But there is evidence that
beneath the ice, liquid water still flows. Much of the water on
Mars has gone underground. And some of it certainly
has migrated down to a depth where it's warm
enough for it to exist as liquid water. And then when it
gets colder, it's going to be frozen
into a cryosphere, if you like, an ice
part of the subsurface. Then near the
surface, it's going to dry out as the water
can move through the soil and go into the atmosphere. NARRATOR: University of
Arizona scientist Peter Smith is eager to solve the mystery
of Mars's disappearing water. OK. I'm digging a little
trench here to show you what happens if you get
below the absolute hyper arid surface. And you go down
just a foot or so. Because this is
similar to what we're going to be doing on Mars. NARRATOR: Smith is the principal
investigator for NASA's Phoenix Mars mission. It's a robotic probe with one
simple objective, land on Mars and follow the water. What happened to that water? Could have frozen into
underground ice or even aquifers of liquid water. These are something we're
looking for today using radio and radar to penetrate
through the surface and try and locate these
reservoirs of water. NARRATOR: Smith believes that
Arizona's Wilcox Playa reflects what scientists will find
when Phoenix finally scratches the red martian surface. PETER SMITH: Even though
the surface is parched and salty and dry, just within
six inches of the surface is a very wet clay, like
a reservoir of water. And there's a whole
ecosystem of life that's living in these wet
soils and in these clays. When it rains, it
comes to the surface. And in fact, you
see little pools where actually brine shrimp that
are locked into these soils. We wonder, if we get down under
the surface in the right place on Mars, and that is
the permafrost region, can we find the same sort
of ecosystem around the ice, melting over time as
climate changes, that's habitable for some sort
of martian life forms? NARRATOR: Some believe that life
on Earth originated on Mars, and that its strange
transformation foretells our destiny. If that's true,
finding Mars's water may lead us back to our cosmic
beginnings and into the future. [dramatic music] When it comes to the
universe, what we know is surpassed only by what
we have yet to learn. And of all the
unexplained mysteries, one remains the greatest of all. Did anything come
before the Big Bang? Or was that event truly the
beginning of everything? And if it was, what was
the spark that lit it? This is the greatest
mystery in all of science. What started creation itself? Big Bang Theory has this
tremendous hole in it. We are clueless. We are clueless as to what
set the Big Bang into motion. [suspenseful music] NARRATOR: The Big Bang
is the cosmological model for the birth of our universe,
13.7 billion years ago. Everything in our universe can
be traced back to that moment. ANDREAS ALBRECHT: There seems
to be this mysterious point at the beginning. And we call that
the singularity. But even though it's mysterious
and has many open questions associated with it, it still
makes a good starting point for our timeline. NARRATOR: But our
scientific instruments are blind and deaf to the
period before the Big Bang, if such a period existed at all. The singularity
is like a horizon that we can never see beyond. Because in the creation, time
was created along with space and along with matter. And the Big Bang is
just that sort of event. And therefore, it's impossible
to know what happened before the creation of it. [dramatic music] NARRATOR: Nevertheless,
scientific speculation as to what happened before
the Big Bang is something that intrigues the greatest
minds in astrophysics. Some theorists believe that our
universe experiences big bangs at regular intervals. This cyclic model proposes
that every trillion years, there's a big bang, after
which the universe expands before again collapsing, setting
the stage for another big bang. ANDREAS ALBRECHT:
There's interesting ways that can connect with the
story of a previous universe. The end of one universe can
bring the beginning of another. KIM STANLEY ROBINSON: Maybe
there never was a start, that it's somehow been
ongoing from an earlier moment and never had a creator at all. [mysterious music] NARRATOR: But we might be
closer to an explanation of the pre-big
bang than we know. The cosmic reverberations from
the Big Bang that still echo through the universe we
actually hold the answer to the moment before
the singularity. ANDREAS ALBRECHT: Turns
out, these standing waves are key to how we understand
the universe today. Inflation gives the universe
one big hit at the beginning, just like I'm hitting
the pot right here. It forms the standing waves. And we can look for those
symmetrical patterns in the cosmic radiation today. So we sent our satellites out. We observed the radiation of
the symmetrical standing waves. MICHIO KAKU: A new wave
of detectors, gravity wave detectors, will be launched into
outer space in the next decade. Connected by laser
beams, any shock wave from the instant of creation
will jiggle these laser beams. And we'll be able to then
record the vibrations left over from the
Big Bang itself. That's why I'm confident that
we'll be able to probe not just the Big Bang itself, but
even the pre-Big Bang era in the coming decades. NARRATOR: The lasers
will also detect sources of inflationary energy, and
perhaps determine the mechanism that created the Big Bang. If we struggle to solve the
greatest mystery of all, how can we ever hope to really
understand the universe? ADRIENNE COOL: Whenever you
get an answer to a question, it almost always leads
to more questions. You make progress, and
mysteries can get solved. But then, there'll
always be more mysteries. RONALD MALLETT: And
we are the result of the universe attempting
to understand itself. That's my conception of
our place in the universe. And so that makes it
difficult to understand. But nevertheless, it
might be possible. [dramatic music] The universe is
constantly changing. But the laws, the laws
of physics are immutable. They don't change. And that gives us hope
that out of all this chaos, we'll be able to explain how
it all got here to begin with. In our ever-changing universe,
the unexplained mysteries will continue to elude us. But we're edging ever closer to
unlocking the ultimate secrets, the keys to our past, and
the pathways to our future. While science has made
sense of many things, there is still plenty
left to be discovered about our vast, dark,
and mysterious universe. [dramatic music]
