All across the immense reaches of time and
space, energy is being exchanged, transferred, released, in a great cosmic pinball game we
call our universe. How does energy stitch the cosmos together,
and how do we fit within it? We now climb the power scales of the universe, from atoms,
nearly frozen to stillness, to Earth’s largest explosions. From stars, colliding, exploding, to distant
realms so strange and violent they challenge our imaginations. Where will we find the most powerful objects
in the universe? Today, energy is very much on our minds as
we search for ways to power our civilization and serve the needs of our citizens. But what is energy? Where does it come from?
And where do we stand within the great power streams that shape time and space? Energy comes from a Greek word for activity
or working. In physics, it’s simply the property or the state of anything in our universe
that allows it to do work. Whether it’s thermal, kinetic, electro-magnetic,
chemical, or gravitational. The 19th century German scientist Hermann
von Helmholtz found that all forms of energy are equivalent, that one form can be transformed
into any other. The laws of physics say that in a closed system
- such as our universe - energy is conserved. It may be converted, concentrated, or dissipated,
but it’s never lost. James Prescott Joule built an apparatus that
demonstrated this principle. It had a weight that descended into water and caused a paddle
to rotate. He showed that the gravitational energy lost by the weight is equivalent to
heat gained by the water from friction with the paddle. That led to one of several basic energy yardsticks,
called a joule. It’s the amount needed to lift an apple weighing 100 grams one meter
against the pull of Earth’s gravity. In case you were wondering, it takes about
one hundred joules to send a tweet, so tweeted a tech from Twitter. The metabolism of an average sized person,
going about their day, generates about 100 joules a second, or 100 watts, the equivalent
of a 100-watt light bulb. In vigorous exercise, the power output of
the body goes up by a factor of ten, one order of magnitude, to around a thousand joules
per second, or a thousand watts. In a series of leaps, by additional factors
of ten, we can explore the full energy spectrum of the universe. So far, the coldest place observed in nature
is the Boomerang Nebula. Here, a dying star ejected its outer layers into space at 600,000
kilometers per hour. As the expanding clouds of gas became more
diffuse, they cooled so dramatically that their molecules fell to just one degree above
Absolute Zero, one degree above the total absence of heat. That’s around a billion trillionths of a
joule, give or take. That makes the signal sent by the Galileo
spacecraft, as it flew around Jupiter, seem positively hot. By the time it reached Earth,
its radio signal was down to 10 billion billionths of a watt. Now jump all the way to 150 billionths of
a watt. That’s the amount of power entering the
human eye from a pair of 50-watt car headlamps a kilometer away. Moving up a full seven powers of ten, moonlight
striking a human face adds up to three hundred thousandths of a watt. That’s roughly equivalent
to a cricket’s chirp. From there, it’s a mere five powers of ten
to the low wattage world of everyday human technologies. Put ten 100-watt bulbs together. At 1000 joules
per second, 1000 watts, that roughly equals the energy of sunlight striking a square meter
of Earth’s surface at noon on a clear day. Gather 200 bulbs, 20,000 watts is the energy
output of an automobile. A diesel locomotive: 5 million watts. An advanced jet fighter: 75 million watts. An aircraft carrier, almost two hundred million
watts. The most powerful human technologies today
function in the range of a billion to 10 billion watts, including large hydro-electric or nuclear
power plants. At the upper end of human technologies, was
the awesome first stage of a Saturn V rocket. In five separate engines, it consumed 15 tons
of fuel per second to generate 190 billion watts of power. How much power can humanity marshal? And how
much do we need? Long before the launch of the space age, visionaries
began to imagine what it would take to advance into the community of galactic civilizations. In the 1960s, the Soviet scientist, Nicolai
Kardashev, speculated that a Level 1 civilization would acquire the technology needed to harness
all the power available on a planet like Earth. According to one calculation, we are .16%
of the way there. This is based on British Petroleum’s estimate of total world oil
consumption, some 11 billion tons in 2007. Humans today generate about two and a half
trillion watts of electrical power. How does that stack up to the power generated by planet
Earth? Deep inside our planet, the radioactive decay
of elements such as uranium and thorium generates 44 trillion watts of power. As this heat rises to the surface, it drives
the movement of Earth’s crustal plates and powers volcanoes. Remarkably, that’s just a fraction of the
energy released by a large hurricane in the form of rain. At the storm’s peak, it can
rise to 600 trillion watts. A hurricane draws upon solar heat collected
in tropical oceans in the summer. You have to jump another power of ten to reach
the estimated total heat flowing through Earth’s atmosphere and oceans from the equator to
the poles… And another two to get the power received
by the Earth from the sun at 174 quadrillion watts. Believe it or not, there’s one human technology
that has exceeded this level. The AN602 hydrogen bomb was detonated by the
Soviet Union on October 30, 1961. It unleashed some 1400 times the combined
power of the Nagasaki and Hiroshima bombs. With a blast yield of up to 57,000,000 tons
of TNT, it generated 5.3 trillion trillion watts, if only for a tiny fraction of a second. That’s 5.3 Yotta-watts, a term that will
come in handy as we now begin to ascend the power scales of the universe. To Nikolai Kardashev, a Level 2 civilization
would achieve a constant energy output 80 times higher than the Russian superbomb. That’s equivalent to the total luminosity
of our sun, a medium-sized star that emits 375 yotta-watts. However, in the grand scheme of things, our
sun is but a cold spark in a hot universe. Look up into Southern skies and you’ll see
the Large Magellanic Cloud, a satellite galaxy of our Milky Way. Deep within is the brightest
star yet discovered. R136a1 is 10 million times brighter than the
sun. Now if that star happened to go supernova,
at its peak, it would blast out photons with a luminosity of around 500 billion yottawatts. To advance to a level three civilization,
you have to marshal the power of an entire galaxy. The Milky Way, with about two hundred billion
stars, has an estimated total luminosity of 3 trillion yotta-watts, a three followed by
36 zeros. The author Isaac Asimov imagined a galaxy-scale
civilization in his Foundation series. Galaxia, he called it, is a super-organism
that surpasses time and space to draw upon all the matter and energy in a galaxy. But who’s to say that’s the upper limit
for civilizations? To boldly go beyond Level 3, a civilization
would need to marshal the power of a quasar. A
quasar is about a thousand times brighter
than our galaxy. Here is where cosmic power production enters
a whole new realm, based on the physics of extreme gravity. It was Isaac Newton who first defined gravity,
as the force that pulls the apple down and holds the earth in orbit around the sun. Albert Einstein re-defined it in his famous
General Theory of Relativity. Gravity isn’t simply the attraction of objects
like stars and planets, he said, but a distortion of space and time, what he called space-time. If space-time is like a fabric, he said, gravity
is the warping of this fabric by a massive object like a star. A planet orbits a star when it’s caught
in this warped space like a ball spinning around a roulette wheel. Some scientists began to wonder: if matter
became dense enough, could it warp space to such an extreme that nothing could escape
its gravity, not even light? With so much power being emitted from such
a small area, scientists suspected that quasars were actually being powered by black holes. How a totally dark object can do this has
been narrowed by decades of observations and theory. If a black hole spins, it can turn into a
violent, cosmic tornado. Gas and stars begin to flow in along a rapidly
rotating disk. The spinning motion of this so-called “accretion disk” generates magnetic
fields that twist up and around. These fields can channel some of the inflowing
matter out into a pair of high-energy beams, or jets. Gas and dust nearby catch the brunt of this
energy, growing hot and bright enough to be seen billions of light years away. Amazingly, the power of a black hole can rise
to even greater extremes at the moment of its birth. As a giant star ages, heavy elements like
iron gradually build up in its core. As its gravity grows more intense, the star
begins to shrink, until it reaches a critical threshold. Its core literally collapses in on itself. That causes the star to explode in a supernova.
And now, in death, the star can unleash gravity’s true fury. In the violence of the star’s death, gravity
can cause its massive core to collapse to a point, forming a black hole. In some rare cases, the new-born monster powers
a jet that accelerates to within a tiny fraction of the speed of light. For a few minutes, these so-called “gamma
ray bursts” are known to be the brightest events since the big bang… Three orders of magnitude above a quasar,
at a billion billion yotta-watts, a ten with 42 zeros. Remarkably, they are still not the most powerful
events known. Albert Einstein‘s equations contained an
astonishing prediction: that when massive bodies accelerate or whip around each other,
they can stir up the normally smooth fabric of space-time. They produce a series of waves that move outward
like ripples on a pond. Scientists are now hoping to detect these
gravitational waves, and verify Einstein’s prediction… using precision lasers and some
of the most perfect large-scale vacuums ever created. At the Laser Interferometry Gravitational
Wave Observatory, known as LIGO, they are hoping to record… The collision of ultra-dense remnants of dead
stars known as neutron stars and of black holes. According to computer simulations, as two
black holes spiral into a fateful embrace, the energy carried by each gravity wave rises
five orders of magnitude above a gamma ray burst, to a hundred billion trillion times
the power of our sun. Does the collision of black holes define the
known power limits of our universe? Perhaps not. As turbulent as the environment of a black
hole might be, its true power may well lie deep in its core. A black hole’s mass is enshrouded within
a dark sphere called the event horizon. Since the 1920s, scientists have described
the mathematics of the event horizon as the equivalent of a waterfall. It’s the point
of no return, beyond which water falls freely into the gorge. At the event horizon of a black hole, space
itself falls freely in at the speed of light. If the black hole is spinning, then the flow
spirals down and around an inner horizon that envelops the singularity. That’s the central
region where space-time becomes infinitely warped. Any matter that rides this river of space
whips around the inner horizon so fast that centrifugal force tends to fling it back out. As that happens, it collides with matter that’s
streaming in, whipping up a ferocious cosmic storm. The energy of the colliding streams feeds
upon itself, rising to what may well be a limit imposed by nature. It dissipates only
as it falls into the singularity and disappears. Fortunately, for us, gravity walls off such
energy extremes behind the event horizon, where they cannot affect the rest of the universe. And so here we sit. Our world is nestled within
a vast stream of cosmic energy, somewhere between the spin of an electron and the maelstrom
of a black hole. There’s no telling whether a future Earth
civilization will be able harness enough energy to advance into the cosmos. For now, as we tap into the tiny morsels of
power at our disposal, we venture a closer look at a universe blazing with activity. We are its product and its star struck admirer. 1
