NARRATOR: In the beginning,
there was darkness. And then, bang. Giving birth to an endless
expanding existence of time, space, and matter. Every day, new discoveries
are unlocking the mysterious, the mind-blowing, the deadly
secrets of a place we call the universe. Energy, the ultimate
galactic transformer. Forever morphing from
one form to another. It powers our planet
and everything else in the universe. But what exactly is it? Where did it all come from? And how do we get more? Energy can be neither
created, nor destroyed. It can only be transformed
from one type to another. NARRATOR: This transformation
sometimes goes to the extremes in objects like black holes. Could a future civilization
harness that power? What a neat way to
get rid of your garbage and solve your energy
crisis all at the same time. NARRATOR: And what if
our universe's energy was transferred to
another place in time? What if a passageway opens
up to a parallel universe and bleeds off some
of that energy? Life wouldn't be able
to withstand that. NARRATOR: This is
the story of energy, from the Big Bang to
your own backyard. Charge up your
engines as we follow the trail of extreme energy. [music playing] Energy is a cosmic chameleon. It drives our universe by
constantly changing form. It power's
acceleration, expansion, and apocalyptic impacts. Everything in our
universe is energy. You're energy. Trees are energy. The dirt is energy. And even the empty space
between the stars is energy. NARRATOR: But where does all
this ever-changing energy come from? All of the energy to see
around us every day actually comes from the very beginning of
the universe, billions of years ago. When you see a car
accident on the highway, that's a very energetic event. Cars get mangled. There's a big noise. But where did the
energy come from? Well, the energy comes from the
energy of motion, of the two cars before they crashed. NARRATOR: But where did
the cars get their energy? From gas. A fossil fuel that
gets its energy from plant life that was
living millions of years ago. Plant life that got its
energy from the sun, which gets its energy
from nuclear reactions inside the core. Those nuclear reactions
get their energy from the particles that were
created at the time of the Big Bang. NARRATOR: All the many forms
of energy we see around us come from the Big Bang. [music playing] The beginning of the universe. The origin of all the matter
and energy in the universe is really, the Big Bang. The creation of the
universe itself. Now we think that,
in fact, the Big Bang was the sudden expansion of
a very small amount of space into a very large space, driven
by a weird kind of an energy. NARRATOR: We're not
sure what type of energy kick-started the Big Bang. But whatever it was,
in one brief instant, it produced all the
energy in our universe. Past, present and future. [music playing] This is one of the most
important and surprising aspects of energy. In black holes, exploding stars,
or even power plants on Earth, it can be neither
created, nor destroyed. It can only be transformed
from one type to another. [music playing] If the laws of
physics in the universe never changed in the past and
don't change in the future, then no energy can be
created or destroyed. It can only be transformed. NARRATOR: Transformation is
the key to how energy works. The universe is filled with many
forms of energy, such as light, sound, thermal, and chemical. The most common among
them is potential energy-- the stored or pent up
energy of an object-- and kinetic energy-- the
movement of an object. And all forms of energy
are constantly converted into other forms of energy. When you fire a
gun at a target, you might think that once
the bullet hits the target that that energy is gone,
but it's not actually gone. It's actually just been
transformed into another type of energy. The chemical potential
energy in the gunpowder has been converted into the
kinetic energy of the bullet. Sound waves, heat,
and whatever energy gets transferred
into the target. Maybe causing it
to move or explode. [music playing] NARRATOR: Even the human
body is a fine-tuned energy transforming machine. A good way to think about how
we transform energy is eating. Humans eat a certain amount
of calories every day. And then whatever
physical activity they do, they do that and
burn off that certain amount of calories. And you have to continue to
eat because you continue to be active and burn off calories. NARRATOR: Incredibly,
Albert Einstein realized that energy and matter
are really the same thing. And one can be converted
into the other. That's the meaning of
his famous equation-- E equals MC squared. Einstein came up with a way
to explain that everything in this universe is energy. Matter is energy. If you weight, say, 100
kilograms, that's your mass. And if you take that
and you multiply that by the speed of light
and then multiply that by the speed of light, then
you get the amount of energy that exist within your body. Actually, about 1,000 times
more energy is in your body than there was in the largest
nuclear weapon detonated by mankind. [music playing] NARRATOR: Objects may have
the same amount of energy, but that doesn't mean they
have the same amount of power. The key ingredient is how
quickly the energy is released. Power is equal to
energy per unit time. So even something with a
really small amount of mass, like, say, this cupcake, would
have the equivalent energy of about a million tons of TNT. We all know that cupcakes don't
spontaneously explode and emit a million tons of TNT. If I eat a cupcake, it only
gives me about 200 calories of energy over several hours. Whereas, if I have
a stick of dynamite, that same amount of energy
would be released in, say, a millionth of a second. So the TNT has much more
power, even though it has the same amount of energy. [music playing] If you have a pizza and
you're going to eat that pizza. Say you eat 1,000
calories worth of pizza. That might be a big
meal, but your body has to convert the
matter of that pizza into that 1,000 calories. And it's really
not that efficient. Take, for example, the same
mass in TNT or dynamite. When you light the fuse on
that, you get way more energy. NARRATOR: All of the
energy we use here on Earth to feed our bodies, power
our electronic devices, and light our homes ultimately
comes from outer space. Some of the most extreme
transformers of energy are stars, including our sun. At any given second, the
sun is putting out about 10 to the 26 watts. That means a one with
26 zeros after it. That's like 400 billion nuclear
weapons all in one second. That's how much energy
we're getting from the sun at any given second. [music playing] NARRATOR: Stars, like our sun,
produce many forms of energy. But it all began with gravity. All gravity means is that
we've observed that all matter falls towards all other matter. And it's interesting that
you can use the gravity to transform energy from
one type to another. If I hold a rock up here, it
has a certain potential energy. And then I let it go. Gravity turns that potential
energy to kinetic energy, until it hits the ground. NARRATOR: Over 13
billion years ago, gravitational energy
gathered up dust and gas to form the first stars. Once a star is formed
through gravitational energy, it then produces nuclear energy. Stars are powered
by nuclear fusion. So this is when you take
multiple hydrogen atoms and smash them together to
produce heavier elements like helium or carbon and oxygen
and nitrogen. When this fusion process happens, the
enormous energy of what's called the strong nuclear
force is liberated. And that is what
lights up the star. NARRATOR: Nuclear fusion
within stars, like our sun, then produces a form
of energy called electromagnetic radiation. These are oscillating waves of
photons or particles of light. On Earth and in space,
electromagnetic radiation consists of a
spectrum of energy. On the low end are radio
waves, with low frequencies and very long wavelengths. On the high end of the
electromagnetic spectrum are gamma rays, with high
frequencies and extremely short wavelengths. Each photon of
electromagnetic radiation takes up to 150,000
years to actually get from the center of
the sun to the surface before it can escape
and head towards Earth. Luckily for us, our
atmosphere blocks most of the
dangerous wavelengths of electromagnetic energy,
which are ultraviolet, x-rays, and gamma rays, from
reaching our world. But it allows visible light,
infrared, and radio waves to pass through. Light and infrared
energies are absorbed by landmasses and oceans and
then converted to heat energy. The sun is
continually emitting electromagnetic radiation, which
is giving us heat energy here on Earth and in space. NARRATOR: Humans have found
clever ways to harness the energy of the universe. We've learned to transform solar
radiation into heat, as well as electrical energy. One of the most
common technologies we use to harness the power
of sunlight is solar panels. Solar panels are usually made
out of semiconductors, which are light sensitive. So when sunlight hits
the silicon solar array, it generates charges. Those charges are then swept out
of the semiconductor material and that generates an
electrical current. NARRATOR: Electricity can be
generated from one solar cell or a solar farm, holding
550,000 solar panels. And those currents
can charge everything from a home to a hot sports car. [music playing] Stars are awesome
transformers of energy. Here on Earth, we are
constantly bombarded with the sun's electromagnetic
energy in the form of light. In turn, we convert
it into other energies to power some of the
most unlikely things in our everyday world. We're here at
Tesla Motors today, to see how electromagnetic
energy can be converted into mechanical energy, which
is used to power this high end sports car here. All it takes is
simple electricity from your average wall socket. So if we plug the car in, like
so, we're now taking energy from the wall socket and we're
using it to charge up the car's battery. The battery, located
right here, is used to run the
car's electric motor. So the computer inside the
car, which is right here, takes energy from
the battery and uses it to turn the single
electric motor, which powers the car at
astonishing speeds, actually. So you can imagine, if you
had, say, solar panels on top of your house and you
were to plug the car in, your car would literally
be running off of sunlight. [music playing] All right. Here we go. NARRATOR: And transforming
sunlight into electricity has its advantages. Electric vehicles accelerate
faster than gas vehicles. Because electric motors provide
full torque immediately, while gas engines
have to rev up. The Tesla here can do
zero to 60 in 3.9 seconds. And that makes it faster than
just about any other production gasoline-powered car there is. This just illustrates
the great power of electromagnetic energy. Isn't science fun? NARRATOR: Our sun is responsible
for fueling almost everything in our world by transforming its
energies from one useful form to yet, another. Green plants convert solar
energy into chemical energy through photosynthesis,
which feeds all living things, including humans. I get energy from my
cornflakes because the corn in the flakes got their energy
from photosynthesis of sunlight that converts sunlight
into sugar-- carbohydrates. All kinds of molecules have
bonds between the atoms and the molecules
that when they break, release energy and give us
the energy that we need when we exercise. NARRATOR: And this life cycle
of energy doesn't end here. Over millions of years,
the decomposed remains of dead plants and animals
are compressed underground and converted into fossil fuels. They come in many forms,
including coal, petroleum, and methane. When we burn oil
or natural gas, we're really liberating the
energy from sunshine that was collected by plants
thousands, tens of thousands, hundreds of thousands
of years ago and stored underground in
fossil fuel repositories. NARRATOR: Fossil
fuels are considered non-renewable resources. This doesn't mean their energy
is completely destroyed, but that they can't be
replenished naturally in a short period of time. When we talk about
non-renewable energy sources like, say, burning fossil fuels,
we don't mean that energy is gone from the universe. What we mean is that that energy
source has been transformed into a form that's
no longer useful. Like, say, for
example, waste heat. NARRATOR: The sun provides
much of the energy essential for our survival. But this energetic
powerhouse can also produce lethal energies. [music playing] November 2006. NASA's Swift Observatory
witnesses a frightening event. The largest stellar
flare ever observed releases energy equal to 50
million trillion atomic bombs. The killer flare fires energy
in the form of X-rays that would obliterate most life on
Earth if it came from our sun. Fortunately, for us, this
radiation came from the star Il Pegasi, which is
135 light years away. Even so, this incident
illustrates the deadly energy being released from
stars, including our sun. A solar flare is a
relatively sudden release of a tremendous
amount of energy. This energy comes
from magnetic energy. A bunch of tangled
magnetic fields suddenly release
this radiated energy. It can be thought of as a bunch
of stretched, twisted rubber bands. That's the magnetic field lines. And eventually, they just snap. And that snapping releases
the energy and channels it outwards, from a relatively
localized region on the sun's surface. Solar flares can reach as
much as 15 million degrees because it's converting magnetic
energy into heat energy. And massive amounts of magnetic
energy into that energy. NARRATOR: Solar flares can
occur several times a day during high solar activity. When they're
erupting, each flare can produce as much thermal
energy in a few minutes as the entire sun
produces in one second. If some of the high energy
charged particles generated by solar flares are
headed in our direction, they'll be deflected by
another energy source-- the Earth's magnetic field. It's produced by
electric currents that flow in its molten core. These currents are
hundreds of miles wide. And move at thousands of miles
per hour as the Earth rotates. This powerful magnetic field
passes through the Earth and enters space. The Earth's magnetic
field stops or deflects most of the charged particles
that come at us from the sun or from interstellar space. So this is a really good thing. Because it would be
really bad for life on Earth if a lot of these
very high energy particles made it to the ground and
were to hit our bodies. NARRATOR: A massive
star can send off flares for 10 billion years. And when the star
nears death, it doesn't mark the end
of the transformation of extreme energy. In fact, it's just
the beginning. Once you have the beginning
of a star, where it does start the nuclear fusion, then the
nuclear fusion continues on and it will burn until all the
hydrogen is used up, basically. NARRATOR: Deprived
of the nuclear energy to support itself, a massive
dying star finally collapses. Igniting a supernova explosion. [music playing] A supernova can
radiate as much energy as the sun will emit
over its entire lifespan. Stars exist in a
balance between energy from a nuclear furnace on the
inside and gravitational pull of all the mass of it
collapsing in on itself. And at some point, when
the nuclear furnace starts to die out, the
gravitational attraction becomes the final
winner of that conflict. It collapses. And it emits a bunch of light. And it's due to gravity
overcoming the nuclear furnace in the star. Now, it's important
to keep in mind that the energy of
an exploding star isn't simply created
out of nothing. Again, it's energy that's
transformed from one type to another. The core of a massive
star collapses, releasing a lot of
gravitational potential energy. That energy then is
channeled into neutrinos, into the kinetic energy
of the ejected material, and into the visible
energy that we observe. [music playing] NARRATOR: Supernovas are one of
the most explosive transformers of energy in space. However, 99% of the energy
released during a supernova is converted into
something that's actually invisible to the naked eye-- strange, ghostly particles
called neutrinos. Neutrinos are nearly massless
energetic particles that move at almost the speed of light. And pass through matter
virtually undisturbed. Every second, more than 50
trillion solar neutrinos pass through the human
body without us knowing it. The likelihood of
one of them interacting with a particle in
your body is so low that you don't notice it. And even if it did happen, it
would be just a little blip of energy that your body gets. Which is much less significant
than all the other blips of energy it gets from other
kinds of particles that are running into such
as light or radiation that's naturally
produced from the Earth. [music playing] NARRATOR: Neutrinos were
once impossible to detect. They traveled right
through the Earth and exited back into
space unnoticed. But in Heda, Japan, over
3,000 feet underground lives the Super K Observatory. It houses a massive
stainless steel tank containing ultra pure water. It's been discovered that
when neutrinos interact with the electrons or
atomic nuclei in water, they produce a charged
particle, which creates a flash of ultraviolet light. As that particle
streams through the water, it actually gives out a
tiny blip of radiation that can be measured by those
little light detectors, which then says that's a neutrino. NARRATOR: Could these stealthy
particles be a source of energy here on Earth? That's what Alan K.
From Chicago, Illinois wanted to ask the universe. So he texted us. How can we harness energy from
neutrinos emitted by the sun? Interesting question, Alan. It turns out that neutrinos
are incredibly hard to detect. So we probably, can't harness
the sun's neutrino energy. Also we don't really want
to because only about 3% of the sun's energy is
in the form of neutrinos. It's much easier to
harness the sunlight and there's much more of it. [music playing] NARRATOR: Neutrinos may not be
able to alleviate our energy crisis. But lurking in each galaxy
exists a ravenous beast that just may be the most
fuel efficient engine in outer space. [music playing] The ability to convert energy
from one form to another has inspired innovative ideas
for future space colonization. Supermassive black holes
reside in the centers of most galaxies,
including our Milky Way. They can store and
unleash the energy of billions of supernovas. When the supermassive
black holes were forming, a tremendous amount of
gravitational potential energy was converted into radiated
light and other forms of energy. Because you had
a lot of material get compressed into
a very small volume, it had to give up
a lot of energy. And a supermassive black
hole is 10 billion sun's worth. That means it has the equivalent
mass of 10 billion stars just, all packed into a
very tiny space. [music playing] NARRATOR: January 2008. NASA's Chandra X-ray telescope
unravels a puzzling mystery about the transformational
energies produced by a black hole. It detects a supermassive
black holes powerful gravitational energy
drawing in a nearby star. As the gluttonous beast gorges
on the star, it spins wildly. Sometimes approaching
the speed of light. This kinetic energy twists
up the gas and debris falling into the hole to form a fast
spinning rotational accretion disk. This rotating material is then
released in powerful jets. This extremely
high energy material spiraling around the black
hole creates a very large magnetic field. Now some of the material
actually follows those magnetic field lines
and gets shot out along them, forming a big
powerful jet that's sort of like a blowtorch. NARRATOR: Recent
computer simulations have shown that if the
extreme kinetic rotational energy from a black hole's
spin could be harnessed, these black monsters
could become the ultimate galactic batteries. Wouldn't it be
great if you could have a spinning black hole
just spinning there out there in space. And you build this
thing in orbit around it that extracts energy from that? And that would give you
a huge amount of energy to fuel your super
advanced civilization. [music playing] NARRATOR: And black
holes may not only be responsible for generating
different forms of energies. They may serve a dual purpose
as a galactic recycling center. One might imagine an
advanced civilization living near a spinning black hole. It could send
garbage trucks close to the spinning black hole
that would dump their garbage at the appropriate time. Those trucks would then
emerge from the vicinity of the black hole with
more energy of motion-- kinetic energy-- than
they had going in. Those trucks could then hit
a turbine, like a windmill, drive the turbine,
generate electrical energy, and thus, light up their cities. What a neat way to get
rid of your garbage and solve your energy
crisis all at the same time. NARRATOR: Black holes may
energize a future space colony. But scientists are
now discovering that the energy from
whirling black holes may be transforming into
something dangerous. Cosmic rays are highly
energetic charged particles. Contrary to their name, they're
not rays of light energy. Rather, they contain very large
amounts of kinetic energy, which can cause deadly effects. Cosmic rays are way more
energetic than anything we've been able to produce on Earth. Hundreds of thousands
of times more energetic. NARRATOR: The most
energetic cosmic rays are called ultra-high
energy cosmic rays. They travel at close
to the speed of light, with ever-increasing brightness. An ultra-high energy cosmic
ray has about as much energy as a tennis ball hit
at 100 miles an hour. That's how fast
the professionals get them going on court. That doesn't sound
like a lot of energy, but actually, there are
trillions of particles making up a given tennis ball. And what's going on is that
you've taken all of that energy and put it into one
subatomic particle. And that's what a
cosmic ray coming in through our atmosphere is like. And so, that's a lot of energy
for a single particle to have. [music playing] NARRATOR: New evidence
suggests that galaxies, known as active galactic
nuclei, may be the source for these
ultra-high energy cosmic rays. These are galaxies that have
super-spinning, supermassive black holes that their cores. Those are, essentially,
extremely powerful generators of energy. They're magnetic
fields, electric fields all spinning around and throwing
up particles at incredibly high rates. Usually generated by a
supermassive black hole at the core. And that sort of system,
black holes especially, are able to produce huge amounts
of energy that can throw out these particles
in all directions. NARRATOR: Ultra-high energy
cosmic rays have become one of the top health threats to
interplanetary space missions. These charged particles
could hurtle right through a spaceship. And penetrate astronauts
like tiny ballistic missiles, ripping apart DNA molecules
and even killing cells. High energy cosmic ray, if
it interacts with human tissue, can do damage to the
DNA in that tissue and lead to a
disruption of the cell. Maybe leading to cancer. NARRATOR: And cosmic
rays may not only threaten space travelers. Every second, cosmic rays
bombard our Earth's atmosphere. Some even penetrate all the
way through and rain down on our planet. The key to cosmic rays
transformational energy is speed. So even if it has really tiny
mass, like most cosmic rays, they've got enormous velocity. So their kinetic energy can
be really, really large. NARRATOR: When they strike
the Earth's atmosphere, they collide with molecules,
mainly oxygen and nitrogen. This produces a storm
of energy in the form of ultraviolet radiation that
cascades down on our planet. Those cosmic rays are coming
from outer space all the time, 24 hours a day. Just impinging upon
the outer atmosphere and running into
the air molecules. And producing
showers of particles that we can detect here on
the surface of the Earth. [music playing] NARRATOR: Fortunately, for us,
one original ultra-high energy cosmic ray spreads
its energy out to millions or even
billions of particles. So it's energy, originally in
the form of x-rays and gamma rays, is so dissipated that it's
no longer harmful to humans. However, these cosmic rays
could cut off your cell phone conversation. These air showers, as they're
called, which are produced by the cosmic rays hitting
the outer atmosphere, those could affect electronics
here on the ground. Our computers and cell
phones and other devices that we use every day are
becoming more and more delicate as we miniaturize our circuitry. And that actually makes it
much more sensitive to being disrupted by cosmic rays. [music playing] NARRATOR: In every
corner of the universe, we witness the destructive
nature of energy in motion. Yet, here on Earth, we generate
a unique form of energy that comes from the creation
of our solar system. [music playing Since the beginning of time,
energy has been the universe's long-standing magic act. Constantly changing from
one form to another. One unique type
of extreme energy is the legacy of our
solar system's creation. Geothermal energy comes from
the heat created in the Earth's rocky core, which exists about
4,000 miles below the surface. Our solar system was first
formed about 4 and 1/2 billion years ago, when a
cloud of gas and dust condensed to form the sun
and all of the planets. A small fraction of
that gas and dust consists of
radioactive elements, like uranium 238 and thorium. When the Earth condensed, some
of those radioactive elements got collected into
our Earth's interior. As those elements slowly
decay over billions of years, they heat up the
interior of the Earth. We can access this heat
energy as geothermal energy. NARRATOR: Some areas
of the Earth's surface allow this geothermal
energy to seep through, such as near plate tectonic
boundaries, volcanoes, and geysers. Geothermal energy
can be tapped near plate tectonic boundaries,
where this hot stuff comes up. Produced by exploding stars
long ago that are radioactive and release their
energy over timescales of billions of years. NARRATOR: Geothermal plants
around the world harness heat energy from
superheated reservoirs to create electrical energy. [music playing] Here's how it works. High temperature,
high pressure water is brought to the surface
where it enters a low pressure chamber and flashes into steam. The pressure
created by the steam is channeled through
a turbine, which spins to generate electrical power. Once the steam has
exited the turbine, it is either released into
the atmosphere as water vapor or it cools back
into liquid water and is injected
back underground. In almost all
cases, until recently, geothermal power
plants have been either near plate boundaries
or hot spots. Weak spots in the Earth's
crust through which, the hot magma can come. So since most of
the Earth's surface is not near a plate
boundary, it's been relatively difficult to
tap into geothermal energy. [music playing] NARRATOR: The best
concentration and quality of geothermal
energy exists where there are high levels of
tectonic and volcanic activity. Like the Ring of Fire, which
circles the Pacific Ocean. But excavating close to
plate boundaries is tricky. To get a lot of
consumer energy out of the geothermal
energy of the Earth really requires
digging quite deep, to where the temperatures
are high enough that you get a lot of energy out. The technological challenges
for extracting geothermal energy for consumer use are huge. You either need to
harness a volcano or drill down very,
very deep into the Earth or cap the geysers
in Yellowstone. NARRATOR: But this
type of thermal energy may not be exclusive
to planet Earth. Io, one of Jupiter's
four main moons, has active volcanism like Earth. But the thermal
energy from its core is produced not through the
decay of radioactive elements, but rather, through
tidal heating. Io has an elliptical
orbit around Jupiter. So sometimes it's closer to
Jupiter than at other times. When it's closer to Jupiter,
the tidal stretching of Io is greater than when it's
farther from Jupiter. So as it orbits Jupiter, Io
sort of squishes back and forth. That gives rise to a lot of
rubbing of the interior rocks and they then release energy. The interior gets hot. Magma flows to the
surface and you see a bunch of erupting volcanoes. So that can be thought of
as a geothermal energy. We certainly know that the
inside of Jupiter's moon Io is molten because we
see volcanoes there. And that is the
equivalent of geothermal. I say equivalent
because geo means Earth. So strictly speaking, geothermal
is Earth's interior energy. NARRATOR: Planet Jupiter
may not have a molten core like its moon Io, but
the gas giant's hot interior generates another form
of extreme energy-- wind. The giant planets-- Jupiter and Saturn-- have
very windy atmospheres. They are a very stormy. Not just because of heat
from the sun, but, in fact, largely because of heat
generated on the inside. Their interior parts are
still contracting, releasing gravitational energy, and
converting it into energy of motion of the atmosphere-- winds and storms. This is another example of
the conversion of one form of energy into another. Some of the winds
on the giant planets can travel at immense speeds-- 600 or even 700 miles per hour. Now most of them
are only a few miles per hour, which
still is big compared to even big storms on Earth. But the fastest storms can
travel at 600 or 700 miles per hour. That's really fast. [music playing] NARRATOR: Earth also
benefits from wind energy. But it's source doesn't
come from its core, but rather, directly from space. The source of energy that
we see in winds on Earth is really, solar heating. The sun heats different
parts of the atmosphere by different amounts. And that causes imbalances
that allow the air to flow. That's wind energy-- mechanical
energy-- coming from the sun's electromagnetic energy. That wind energy can then
be used to drive a turbine, converting it into electrical
energy that lights our cities. NARRATOR: Energy has propelled
the evolution of the universe since its birth over
13 billion years ago. But now, science has discovered
a mysterious type of energy that just may be the
cosmic grim reaper. [music playing] Throughout outer space
exists a phantom energy. We don't know where this
mysterious form originated, but it's now believed that it
could destroy life on Earth and maybe, even the
universe itself. In the 1990s, astronomers used
the Hubble Space Telescope and other observatories
to measure the distances of exploding stars
and other galaxies. To their shock, they noticed
something quite peculiar. Recently, astronomers
have discovered by looking at the
distances of supernovae that the universe is
actually, accelerating apart. It's not just expanding, but
it's actually accelerating. Some mysterious energy
is driving the universe apart faster and faster. NARRATOR: Astronomers
realized that the expansion of the universe is speeding up
with time due to dark energy. A strange form of energy
that exists everywhere. It accounts for almost
75% of all mass and energy in the universe. And it's one of the big
mysteries of the universe. It is, in fact, the biggest
mystery of the universe, in some sense. Because dark energy is the
largest component of the energy budget of the universe. NARRATOR: Our current
knowledge and understanding of dark energy is very limited,
even though dark energy comprises almost
75% of all matter and energy in the universe. It would be similar to us having
only explored the landmass on the Earth, when the
ocean comprises almost 75% of all of the surface of Earth. We are just now starting
to explore dark energy. [music playing] Scientists had once thought the
gravitational attraction would cause the expansion
of the universe to slow down with time. The belief was that the
universe was expanding from the Big Bang. And that gravity ought to be
slowing that expansion rate. And the big question
at that time was, is gravity strong enough to
pull everything back together? But we got a surprise. Gravity wasn't slowing
down the expansion. In fact, when we
observed carefully, we discovered that the
expansion was accelerating. NARRATOR: While gravity binds
planets, stars, and galaxies, dark energy appears to stretch
the fabric of space and time. Thereby, pushing galaxies apart. Recent observations have shown
that dark energy is causing our universe to expand
at an ever-faster pace. Over the history
of the universe, the relative amounts
of dark energy and regular gravitationally
attractive matter and energy have changed. Early on, regular
gravitationally attractive energy dominated. And that's because objects
were close together. There wasn't much dark
energy in between them so its cumulative
effect was very small. But as the universe expanded
and galaxies got farther apart from each other, the amount
of space, all of which was filled with dark
energy, increased. Let's suppose we model the
universe as an expanding loaf of raisin bread, where the
raisins are the galaxies-- they don't expand. And the dough is uniformly
filled with yeast. That's like the dark energy. Now suppose we continue to
inject yeast into the baking bread as it expands. It'll expand faster and faster
with time because there's more and more yeast. It'll be accelerating
in its expansion. In a similar way, with time,
there's more and more dark energy in the universe. Thus, accelerating,
speeding up its expansion. NARRATOR: If dark energy
continues to speed up the expansion of our
universe, we could eventually experience the big chill. Clusters of galaxies will
spread thinner and thinner. Galaxies will exhaust their
gas supply to form new stars. And old stars will burn out. The universe will become
dark and insufferably cold. In a universe that expands
forever or nearly forever, eventually, the sun and all
the other stars will burn out. They'll use up
their nuclear fuel. At that point, there
will be basically, no source of energy
for life on Earth. So life as we know it
will cease to exist. NARRATOR: But if this
grim scenario happens, all the energy in the
universe won't disappear because our energy budget has
been fixed since the Big Bang. However, the energy will
become impossible to access. The energy gets spread
out so much and diluted to such an extent, that
it is no longer usable. NARRATOR: But there are
other theories about the fate of our universe energy. In the distant future,
some propose energy could be transferred to
another place, perhaps another universe. According to the
laws of physics, energy can't be
created or destroyed. And all the energy is that
is within our universe has always been here
and will always be here. But what if a wormhole
or something opens up to a parallel universe and
bleeds off some of that energy? It's possible that our universe
would start cooling off because we're leaking,
at that point. And I don't think that
would be a good idea. Because eventually, the universe
would cool off to a point where everything
would freeze out. And life wouldn't be
able to withstand that. NARRATOR: We don't know what
the far future holds for energy in our universe or beyond. But for the time being, it
remains the violent and yet, vital and ever-changing
component of our universe.
