Equipped with his five senses
man explores the universe around him
and calls the adventure Science.
Things around us aren't always what they seem.
ln the everyday world, we use a simple scale, ourselves
to know what's small and what's large.
But what about the worlds that lie beyond?
What is truly large and truly small?
To explore, to observe
to understand the wider world we call the universe:
This is one of the great human adventures.
As we look out at the distant horizon, we may ask ourselves
what is our true place in the universe?
We are all travelers
on an unending voyage of discovery.
More than 25 centuries ago, among the Greek lslands
here at the vibrant crossroads of Africa, Asia and Europe
philosophers devised rational theories about the world around them.
The wondrous waves and foams of nature, they said
could be understood.
One Greek thinker suggested that the Earth moved around the sun.
Another taught that everything, the work of man and nature
was made of particles too small to see.
Others estimated the sizes of the Earth and the moon
and the distances between them, and reasoned
both were spheres.
But it would be centuries before we had the tools to extend our vision
and confirm the wisdom of these early thinkers.
ln the meantime
people around the world gazed on the stars and gave them names.
Most assumed the Earth was the center of an unchanging universe.
Two thousand years passed
before a revolutionary breakthrough was made by a mathematics professor
in the ancient, maritime republic of Venice.
ln 1609, Galileo Galilei
demonstrated an instrument that would soon be called a telescope.
From the tallest bell towers
he showed the device could spot approaching ships
hours before their sails were visible to the naked eye.
Later, when he aimed his telescope at the night sky
Galileo discovered that the moon was a world of mountains.
Jupiter had its own moons
and the Milky Way was a band of countless stars.
Our own cosmic voyage begins here
in the center of Galileo's Venice, St. Mark's Square.
Since the universe is a big place, we could easily get lost
so we'll need signposts to give us a sense of scale.
The acrobats' ring is one meter wide.
The crowd is ten times wider, ten meters across.
Larger by one power of ten.
Now, with every step, every ring
we travel ten times farther from Venice
and our view of the universe is ten times wider.
The 100-meter ring surrounds St. Mark's
and 1,000 meters, one kilometer, the city's center.
As our speed increases, four steps, four powers of ten
reveal all the islands of Venice, the Adriatic Sea and Northern ltaly.
Six steps take in Europe from Germany across to the Balkans.
And soon, we can see the entire planet.
Our home in space.
Eight steps on our outward journey
eight powers of ten, and we pass the farthest reaches of human travel:
The moon.
lf we visualize the paths that the nine planets take
in their orbits around the sun
at 13 steps from St. Mark's Square
the entire solar system comes into view.
And with 15 steps, 15 powers of ten
we can see our sun is just another star.
From here on, our voyage will be measured in light-years.
The distance light travels in an entire year.
Only now do we fly past our nearest neighbor stars
almost five light-years away.
The same journey at the speed of today's spacecraft
would last 100,000 years.
As we cross the perpetual night
our voyage takes us up and out of our sun's neighborhood
near the edge of a great pinwheel of stars.
The Milky Way is actually a spiral galaxy
and our own sun is just one of a hundred billion stars in it.
At this immense scale, 23 powers of ten
each shining light we see is not a star
but an entire galaxy composed of countless stars.
Astronomers have discovered galaxies are flying away from one another.
The universe is expanding.
Our own galaxy, and all the others
form clusters and superclusters of stupendous size
hundreds of millions of light-years across.
And here, about 15 billion light-years from Venice
we approach the outer limits of the visible universe.
What lies beyond this cosmic horizon, we cannot see
and do not know.
While Galileo's telescope allowed us to take an outward voyage
another innovation, here in the Dutch town of Delft
would lead us on an inward journey of discovery.
Over three centuries ago
Anton van Leeuwenhoek perfected the early microscope
and used it to study droplets from the waterways of Holland.
Come on, over here.
As students today make their own discoveries
imagine the moment when van Leeuwenhoek
peered through his more powerful instrument
and discovered a living kingdom in a drop of water.
This busy world of single-cell paramecia
is only one millimeter across.
Three powers of ten smaller than a meter.
The microscope allows us to continue our journey to the realm of the very small.
As we move into the cell nucleus
each new ring now reveals a world
ten times smaller in diameter than the last.
Deep within the nucleus
we come upon truly remarkable constructions.
Long, spiraling molecules of DNA.
DNA holds the chemical codes
for the reproduction of most organisms on the planet.
Whether they're paramecia, people or petunias.
Voyaging on, we see that molecules
are made of even smaller parts called atoms.
The tiny world of the common atom is very strange indeed.
lts six electrons seem to swarm everywhere at once.
Now our voyage takes us through a void
that appears as vast as the space between the stars.
Ahead lies the atomic nucleus.
So fantastically small
that if the whole atom were the size of this theater
its nucleus would be like a speck of dust.
Yet the nucleus contains almost all of the atom's mass
packed into particles called protons
and neutrons.
And these, in turn, are made of smaller, more mysterious things called quarks.
Exploring this
the inner frontier of the universe
physicists wonder if quarks might contain
even tinier building blocks of matter.
Scientists are investigating this mystery in an underground tunnel near Chicago
home of the giant Fermilab particle accelerator
designed to create conditions like those after the birth of our universe.
Millions of protons and antiprotons
race through these pipes in opposite directions
nearly at the speed of light. A kind of subatomic demolition derby.
Now our cosmic voyage enters another dimension
the dimension of time
where knowledge is much less certain.
Studying traces of quarks from these collisions
physicists try to learn what our universe was like when it began
after the explosion known as the Big Bang.
One of them outlines the theory.
Welcome to Fermilab.
Today, astronomers see the universe expanding.
lmagine running the expansion backwards.
Billions of years ago
everything must've been packed together at enormous density.
lt seems incredible
but we think that the matter
making up everything we see in the universe
the buildings, trees, people, planets
stars out to the most distant galaxies
was once crammed together into a volume smaller than this.
And then.
Space itself exploded, in a burst of radiant energy.
ln those first dazzling moments
the newborn universe began to expand and cool.
Quarks combined into protons and neutrons
which later attracted electrons to form atoms
and the vast fog lifted.
For hundreds of millions of years
the force of gravities slowly drew matter together into a gigantic web.
The architecture of the cosmos.
Two billion years passed
clouds of gas and dust condensed like giant water drops
along the cosmic strands and formed galaxies.
Where the great ridges of matter crossed
galaxies came together in clusters.
Some galaxies evolved into gigantic discs
and spirals of stars, gas, and dust.
Neighboring galaxies trapped by their mutual gravity
draw together in the fantastic collision.
ln real time, it would last a billion years.
The force of gravities stretch long tails of gas and stars
from the huge new galaxy.
And yet stars almost never collide
so vast are the distances between them.
Perhaps ten billion years pass
and we encounter our own galaxy:
The Milky Way.
ln it, stars have formed
and some have died.
Stars are nuclear furnaces.
They shine until they use up their fuel.
Massive stars end explosively.
These exploding stars, or supernovas
send out the elements of life:
The oxygen we breathe, the carbon in our muscles
the iron in our blood.
Now a cloud of cosmic gas
sprinkled with these elements, comes together in the grip of gravity.
A new star, our sun, ignites.
Around it, planets form.
ln their infancy, over four billion years ago
our Earth and moon were bombarded constantly
by cosmic dust, asteroids
and comets.
With violent impacts and volcanic gases
acid rain, and potent ultraviolet radiation from the sun
the young Earth was a very hostile world.
And yet the basic ingredients of life are already here.
Water
carbon
and energy.
Molecules, sheltered by the sea, somehow combined
multiplied, and gave rise to life.
For millions of years, Earth's only organisms were tiny bacteria.
Some, called blue-green bacteria
slowly released tiny bubbles of oxygen
and profoundly changed the atmosphere.
Above the clouds, some of this oxygen formed a thin layer of ozone
blocking most of the sun's ultraviolet rays.
ln this changed environment
new organisms flourished in the Earth's waters.
Colonies of green algae produced more oxygen.
Then, organisms evolved in an astonishing variety of forms.
Some with shells or skeletons for protection and support.
Others evolved complex life cycles, like this tiny crustacean.
The shallow waters of the seas filled with a teaming diversity of life forms.
Life's next challenge was to colonize the harsh, dry land.
Bacteria were first, followed by algae, plants, and animals.
Vertebrates appeared on land, feeding on both plants and animals
and gave rise to larger and larger life forms.
Some of them conquered the realm of the air
and others, the great open plains.
Our cosmic voyage, from the Big Bang to the appearance of humans
took about 15 billion years.
From the beginning, we were explorers
inventors and technicians.
And in a few thousand years, just an instant in cosmic time
curiosity and technology would take us back toward the stars.
Since it was launched into orbit
the Hubble space telescope has captured images
that reveal ever more beautiful
and mysterious regions of the universe, where stars are dying out.
And within the Eagle Nebula
strange towers of glowing gas are giving birth to new stars.
ln the great Orion Nebula
discs of dust seem to be turning into solar systems just like our own.
The grand adventure of cosmic exploration is accelerating rapidly
taking us into realms that once were the stuff of science fiction
like the mysterious black hole.
Here, a red giant star is slowly being consumed
its gases swirling into the depths of a black hole.
Some black holes may be collapsed cores of very massive stars
with gravity so powerful not even light can escape them.
But they can be detected from their trap and swallow nearby stars.
For the first time in our history
we now have strong evidence that there are planets orbiting other stars.
Scientists think there could be millions of earth-like planets in our galaxy alone.
lf so, do any of them have life?
Some radio telescopes search for signals
that may reveal the presence of alien civilizations.
lt's a daunting task.
But, if one day we should receive a signal
it would forever change our view of ourselves
and our universe.
Telescopes, such as the giant Keck Observatory in Hawaii
are like time machines capturing the faint light
that has traveled towards us through all of cosmic history.
The deeper astronomers look into space, the farther back they see in time.
The more we learn about the universe
the more new mysteries we uncover
profound questions for future generations of cosmic explorers.
Will the universe go on expanding forever?
Exactly how did life arise?
Could there be other universes beyond our cosmic horizon?
And are there others elsewhere in the universe
asking the same things?
Even to ask such questions is ambitious.
But look how far we've traveled since our ancestors
took the first steps in our cosmic voyage.
Man must understand his universe in order to understand his destiny.
Who knows what mysteries will be solved in our lifetime
and what new riddles will become the challenge of the new generations?