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  • ''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