COSMOS Episode 1 | Carl Sagan's Universe Begins | Full Documentary (HD)|

Hello, my name is Anne Drianne. When

Carl Sean, Steven Zoder, and I wrote the Cosmos television series in the late 1970s, a lot of things were different.

Back then, the United States and the Soviet Union held the whole planet in a perpetual hostage crisis called the Cold War. The wealth and scientific ingenuity

War. The wealth and scientific ingenuity of our civilization was being squandered on a runaway arms race that employed more than half the world's scientists

and infested the earth with 50,000 nuclear weapons. So much has happened since

weapons. So much has happened since then. The Cold War is history and

then. The Cold War is history and science has made great strides. We've

completed the spacecraft reconnaissance of the solar system, the preliminary mapping of the visible universe that surrounds us, and we have charted the universe within the human

genome. When Cosmos was first broadcast,

genome. When Cosmos was first broadcast, there was no worldwide web. It it was a different world. What a tribute to Carl

different world. What a tribute to Carl Sean, a scientist who took many a punch for daring to speculate that even after 20 of the most eventful years in the

history of science, Cosmos requires few revisions and indeed is rich in prophecy.

Cosmos is both a history of the scientific enterprise and an attempt to convey the soaring spiritual high of its central revelation, our oneness with the

universe.

Now, please enjoy Cosmos, the proud saga of how through the searching of 40,000 generations of our ancestors, we have come to discover our coordinates in

space and in time and how through the awesomely powerful method of science, we have been able to reconstruct the sweep of cosmic

evolution and to find our own part in its great story.

[Music] Heat up here.

The cosmos is all that is or ever was or ever will be. Our contemplations of the cosmos stir us.

There's a tingling in the spine that catch in the voice a faint sensation as if a distant memory of falling from a

great height. We know we are approaching

great height. We know we are approaching the grandest of mysteries. The size and age of the

mysteries. The size and age of the cosmos are beyond ordinary human understanding. Lost somewhere between

understanding. Lost somewhere between immensity and eternity is our tiny planetary home, the Earth. For the first

time, we have the power to decide the fate of our planet and ourselves. This

is a time of great danger, but our species is young and curious and brave.

It shows much promise. In the last few millennia, we have made the most astonishing and unexpected discoveries about the cosmos and our place within

it. I believe our future depends

it. I believe our future depends powerfully on how well we understand this cosmos in which we float like a moat of dust in the morning

sky. We're about to begin a journey

sky. We're about to begin a journey through the cosmos.

We'll encounter galaxies and suns and planets, life and consciousness coming into being, evolving and

perishing. Worlds of ice and stars of

perishing. Worlds of ice and stars of diamond. Atoms as massive as suns and

diamond. Atoms as massive as suns and universes smaller than atoms. But it's also a story of our own planet and the plants and animals that

share it with us.

And it's a story about us. How we

achieved our present understanding of the cosmos. How the cosmos has shaped

the cosmos. How the cosmos has shaped our evolution and our culture and what our fate may be. We wish to pursue the truth no

be. We wish to pursue the truth no matter where it leads. But to find the truth, we need imagination and skepticism both. We will not be afraid

skepticism both. We will not be afraid to speculate, but we will be careful to distinguish speculation from fact. The

cosmos is full beyond measure of elegant truths of exquisite inter relationships of the awesome machinery of

nature. The surface of the earth is the

nature. The surface of the earth is the shore of the cosmic ocean. On this

shore, we've learned most of what we know. Recently, we've waited a little

know. Recently, we've waited a little way out, maybe ankle deep, and the water seems inviting. Some part of our being knows

inviting. Some part of our being knows this is where we came from. We long to return, and we can because the cosmos is

also within us. We're made of star stuff. We are a way of a cosmos to know

stuff. We are a way of a cosmos to know itself. The journey for each of us

itself. The journey for each of us begins here. We're going to explore the

begins here. We're going to explore the cosmos in a ship of the imagination.

Unfettered by ordinary limits on speed and size. Drawn by the music of cosmic

and size. Drawn by the music of cosmic harmonies, it can take us anywhere in space and time. Perfect as a snowflake,

organic as a dandelion seed, it will carry us to worlds of dreams and worlds of facts. Come with

me.

Before us is the cosmos on the grandest scale we know. We are far from the shores of

know. We are far from the shores of earth. In the uncharted reaches of the

earth. In the uncharted reaches of the cosmic ocean, strewn like seafloth on the waves of space are innumerable faint

tendrils of light. Some of them containing hundreds of billions of suns.

These are the galaxies drifting endlessly in the great cosmic dark. In our ship of the imagination, we

dark. In our ship of the imagination, we are halfway to the edge of the known universe. In this, the first of our

universe. In this, the first of our cosmic voyages, we begin to explore the universe revealed by science.

Our course will eventually carry us to a far off and exotic world. But from the depths of space, we cannot detect even the cluster of galaxies in which our

Milky Way is embedded, much less the sun or the Earth.

[Music] We are in the realm of the galaxies 8 billion light years from home.

No matter where we travel, the patterns of nature are the same as in the form of this spiral galaxy. The same laws of physics apply

galaxy. The same laws of physics apply everywhere throughout the cosmos. But we have just begun to

cosmos. But we have just begun to understand these laws. The universe is rich in mystery. Near the center of a cluster of

mystery. Near the center of a cluster of galaxies, there's sometimes a rogue elliptical galaxy made of a trillion

suns, which devours its neighbors.

Perhaps this cyclone of stars is what astronomers on Earth call a quazar.

Our ordinary measures of distance fail us here in the realm of the galaxies. We

need a much larger unit, the lightyear.

It measures how far light travels in a year, nearly 10 trillion km. It measures

not time but enormous distances. In the Hercules cluster, the

distances. In the Hercules cluster, the individual galaxies are about 300,000 light years apart. So, light takes about

300,000 years to go from one galaxy to another. Like stars and planets and

another. Like stars and planets and people, galaxies are born, live, and die. They may all experience a

die. They may all experience a tumultuous adolescence. During their

tumultuous adolescence. During their first 100 million years, their cores may explode, seen in radioight. Great jets

of energy pour out and echo across the cosmos. Worlds near the core or along

cosmos. Worlds near the core or along the jets would be incinerated. I wonder how many planets

incinerated. I wonder how many planets and how many civilizations might be destroyed.

[Music] In the Pegasus cluster, there's a ring galaxy. The wreckage left from the

galaxy. The wreckage left from the collision of two galaxies. A splash in the cosmic pond. Individual galaxies may explode

pond. Individual galaxies may explode and collide, and their constituent stars may blow up as well.

In this supernova explosion, a single star outshines the rest of its galaxy. We are approaching what

galaxy. We are approaching what astronomers on Earth call the local group. 3 million lightyear across. It

group. 3 million lightyear across. It

contains some 20 galaxies.

It's a sparse and rather typical chain of islands in the immense cosmic ocean. We are now only 2 million

ocean. We are now only 2 million lightyear from home. On the maps of space, this galaxy

home. On the maps of space, this galaxy is called M31, the great galaxy in Andromeda. It's a vast storm of stars

Andromeda. It's a vast storm of stars and gas and dust. As we pass over it, we see one of its small satellite galaxies.

Clusters of galaxies and the stars of individual galaxies are all held together by gravity. Surrounding M31 are

hundreds of globular star clusters. We're approaching one of them.

clusters. We're approaching one of them.

Each cluster orbits the massive center of the galaxy. Some contain up to a million separate stars.

Every globular cluster is like a swarm of bees bound by gravity. Every be a sun. From the Pegasus cluster, our

sun. From the Pegasus cluster, our voyage has taken us 200 million lighty years to the local group dominated by

two great spiral galaxies. Beyond M31 is another very

galaxies. Beyond M31 is another very similar galaxy. Its spiral arms slowly

similar galaxy. Its spiral arms slowly turning once every quarter billion years. This is our own Milky Way seen

years. This is our own Milky Way seen from the outside.

This is the home galaxy of the human species. In the obscure backwaters of

species. In the obscure backwaters of the Karina Signis spiral arm, we humans have evolved to consciousness and some

measure of understanding.

Concentrated in its brilliant core and strewn along its spiral arms are 400 billion suns. It takes light a 100,000 years to

suns. It takes light a 100,000 years to travel from one end of the galaxy to the other.

Within this galaxy are stars and worlds and it may be an enormous diversity of living things and intelligent beings and space fairing

civilizations. Scattered among the stars

civilizations. Scattered among the stars of the Milky Way are supernova remnants.

Each one the remains of a colossal stellar explosion. These filaments of glowing

explosion. These filaments of glowing gas are the outer layers of a star which has recently destroyed itself. The gas

is unraveling, returning star stuff back into space. And at its heart are the remains

space. And at its heart are the remains of the original star, a dense, shrunken stellar fragment called a pulsar. A

natural lighthouse blinking and hissing.

A sun that spins twice each second. Pulsars keep such perfect time

second. Pulsars keep such perfect time that the first one discovered was thought to be a sign of extraterrestrial intelligence. Perhaps a navigational

intelligence. Perhaps a navigational beacon for great ships that travel across the light years and between the stars.

[Music] There may be such intelligences and such starships, but pulsars are not their signature. Instead, they are the doeful

signature. Instead, they are the doeful reminders that nothing lasts forever, that stars also die.

We continue to plummet, falling thousands of light years towards the plane of the galaxy. This is the Milky Way. Our

galaxy. This is the Milky Way. Our

galaxy seen edge on billions of nuclear furnaces converting matter into starlight. Some stars are flimsy as a

starlight. Some stars are flimsy as a soap bubble. Others are a 100 trillion

soap bubble. Others are a 100 trillion times denser than lead. The hottest

stars are destined to die young. But red

giants are mostly elderly. Such stars are unlikely to have

elderly. Such stars are unlikely to have inhabited planets. But yellow dwarf stars like the

planets. But yellow dwarf stars like the sun are middle-aged and they are far more common.

These stars may have planetary systems. And on such planets, for the first time in our cosmic voyage, we encounter rare

forms of matter, ice and rock, air, and liquid water. Close to this yellow star is a

water. Close to this yellow star is a small, warm, cloudy world with continents and oceans. These conditions

permit an even more precious form of matter to arise, life. But this is not the Earth.

life. But this is not the Earth.

Intelligent beings have evolved and reworked this planetary surface in a massive engineering enterprise.

In the Milky Way galaxy, there may be many worlds on which matter has grown to [Music]

consciousness. I wonder, are they very

consciousness. I wonder, are they very different from us? What do they look like? What are their politics,

like? What are their politics, technology music religion? Or do they have patterns of

religion? Or do they have patterns of culture we can't begin to imagine? Are

they also a danger to [Music] themselves? Among the many glowing

themselves? Among the many glowing clouds of interstellar gas is one called the Orion Nebula. Only 1,500 lighty years from Earth.

[Music] These three bright stars are seen by Earthlings as the belt in the familiar constellation of Orion the

Hunter. The nebula appears from Earth as

Hunter. The nebula appears from Earth as a patch of light, the middle star in Orion's sword.

But it is not a star. It is another thing entirely. A cloud that veils one

thing entirely. A cloud that veils one of nature's secret [Music] places. This is a stellar nursery. a

places. This is a stellar nursery. a

place where stars are born. They

condense by gravity from gas and dust until their temperatures become so high that they begin to shine. Such clouds mark the births of

shine. Such clouds mark the births of stars as others bear witness to their deaths. And after stars condense in the

deaths. And after stars condense in the hidden interiors of interstellar clouds, what happens to them? The Pletes are a loose cluster of young stars only 50

million years old. These fledgling stars are just being led out into the galaxy, still surrounded by wisps of nebulosity,

the gas and dust from which they formed.

[Music] [Music] There are clouds that hang like ink blotss between the stars. They are made

of fine rocky dust, organic matter, and ice. Inside, a few stars begin to turn

ice. Inside, a few stars begin to turn on. Nearby worlds of ice evaporate and

on. Nearby worlds of ice evaporate and form long cometlike tails driven back by the stellar winds. Black clouds light years across

winds. Black clouds light years across drift between the stars. They're filled

with organic molecules. The building

blocks of life are everywhere. They're

easily made. On how many worlds have such complex molecules assembled themselves into patterns we would call

alive. Most stars belong to systems of

alive. Most stars belong to systems of two or three or many suns bound together by gravity. Each system is isolated from

by gravity. Each system is isolated from its neighbors by the light years.

We are approaching a single ordinary yellow dwarf star surrounded by a system of nine planets, dozens of moons, thousands of asteroids, and billions of

comets, the family of the sun. Only four light hours from Earth is

sun. Only four light hours from Earth is the planet Neptune and its giant satellite [Music]

Triton. Even in the outskirts of our own

Triton. Even in the outskirts of our own solar system, we humans have barely begun our explorations. Only a century ago, we

explorations. Only a century ago, we were ignorant even of the existence of the planet Pluto. Its moon Karon remained undiscovered till

1978. The rings of Uranus were first

1978. The rings of Uranus were first detected in 1977.

There are new worlds to chart even this close to home. Saturn is a giant gas world. If it

home. Saturn is a giant gas world. If it

has a solid surface, it must lie far below the clouds we see. Saturn's majestic rings are made of

see. Saturn's majestic rings are made of trillions of orbiting snowballs.

We are now only 80 light minutes from home. A mere 1 and a half billion

home. A mere 1 and a half billion kilometers. The largest planet in our

kilometers. The largest planet in our solar system is Jupiter. On its dark side, superbolts of lightning illuminate the clouds as first revealed by the

Voyager spacecraft in 1979. Inside the orbit of Jupiter are

1979. Inside the orbit of Jupiter are countless shattered and broken worldlets, the asteroids.

These reefs and shos mark the border of the realm of giant planets. We are now entering the shallows of the solar

system. Here there are worlds with thin

system. Here there are worlds with thin atmospheres and solid surfaces, earthlike planets with landscapes crying out for careful

exploration. This world is Mars.

exploration. This world is Mars.

In 1976, after a year's voyage, two robot explorers from Earth landed on this alien

shore. On Mars, there is a volcano as

shore. On Mars, there is a volcano as wide as Arizona and almost three times the height of Mount Everest. We've named

it Mount Olympus. This is a world of wonders.

Olympus. This is a world of wonders.

Mars is a planet with ancient river valleys and violent sandstorms driven by winds at half the speed of

sound. There is a giant rift in its

sound. There is a giant rift in its surface 5,000 km long. It's called Valis Marinerys, the Valley of the Mariner

spacecraft that teamed to explore Mars from a nearby world.

In this our first cosmic voyage, we have just begun the reconnaissance of Mars and all those other planets and stars

and galaxies. In voyages to come, we

and galaxies. In voyages to come, we will explore them more fully.

But now we travel the few remaining light minutes to a blue and cloudy world third from the sun. The end of our long

journey is the world where we began. Our

travels allow us to see the earth a new as if we came from somewhere else. There are a 100 billion galaxies

else. There are a 100 billion galaxies and a billion trillion stars. Why should

this modest planet be the only inhabited world? To me, it seems far more likely

world? To me, it seems far more likely that the cosmos is brimming over with life and intelligence. But so far, every living

intelligence. But so far, every living thing, every conscious being, every civilization we know anything about lived there on Earth.

Beneath these clouds, the drama of the human species has been unfolding. We have at last come home.

unfolding. We have at last come home.

Welcome to the planet Earth. A place

with blue nitrogen skies, oceans of liquid water, cool forests, soft meadows. A world positively rippling

meadows. A world positively rippling with life. In the cosmic perspective, it

with life. In the cosmic perspective, it is for the moment unique. the only world in which we know with certainty that the matter of the cosmos has become alive

and aware. There must be many such

and aware. There must be many such worlds scattered through space. But our

search for them begins here with the accumulated wisdom of the men and women of our species acquired at great cost over a million years.

[Music] There was once a time when our little planet seemed immense, when it was the only world we could explore. Its true

size was first worked out in a simple and ingenious way by a man who lived here in Egypt in the 3rd century BC.

This tower may have been a communications tower, part of a network running along the North African coast by which signal bonfires were used to

communicate messages of state. It also

may have been used as a lighthouse, a navigational beacon for sailing ships out there in the Mediterranean Sea. It

is about 50 kilometers west of what was once one of the great cities of the world, Alexandria. In Alexandria at that time,

Alexandria. In Alexandria at that time, there lived a man named Eratosines. One of his envious

Eratosines. One of his envious contemporaries called him beta, the second letter of the Greek alphabet, because he said Erosines was second best in the world in everything. But it seems

clear that in many fields, Erosines was alpha. He was an astronomer, historian,

alpha. He was an astronomer, historian, geographer philosopher poet theater critic and mathematician. He was also the chief librarian of the great library

of Alexandria. And one day while reading a

Alexandria. And one day while reading a papyrus book in the library, he came upon a curious account.

Far to the south, he read at the frontier outpost of Sin, something notable could be seen on the longest day of the [Music]

year. On June 21st, the shadows of a

year. On June 21st, the shadows of a temple column or a vertical stick would grow shorter as noon approached. And as the hours crept

approached. And as the hours crept towards midday, the sun's rays would slither down the sides of a deep well, which on other days would remain in

shadow. And then precisely at noon,

shadow. And then precisely at noon, columns would cast no shadows, and the sun would shine directly down into the water of the well.

At that moment, the sun was exactly overhead. It was an observation that

overhead. It was an observation that someone else might easily have ignored.

Sticks, shadows, reflections in wells, the position of the sun, simple everyday matters of what possible importance might they be.

But Eratosineses was a scientist and his contemplation of these homely matters changed the world in a way made the world because Eratosineses had the

presence of mind to experiment to actually ask whether back here near Alexandria a stick cast a shadow near

noon on June the 21st. And it turns out sticks do. An overly skeptical person might

do. An overly skeptical person might have said that the report from Sin was an error, but it's an absolutely straightforward observation. Why would anyone lie on

observation. Why would anyone lie on such a trivial matter? Erosines asked

himself how it could be that at the same moment a stick in Sin would cast no shadow and a stick in Alexandria 800 km

to the north would cast a very definite shadow. Here's a map of ancient

shadow. Here's a map of ancient Egypt. I've inserted two sticks or

Egypt. I've inserted two sticks or obelisks. one up here in Alexandria and

obelisks. one up here in Alexandria and one down here in Sin. Now, if at a certain moment each stick casts no

shadow, no shadow at all, that's perfectly easy to understand, provided the Earth is flat. If the shadow at Sin is at a certain length and the shadow at

Alexandria is the same length, that also makes sense on a flat Earth. But how could it be? Erosines

Earth. But how could it be? Erosines

asked that at the same instant there was no shadow at Sin and a very substantial shadow at

Alexandria. The only answer was that the

Alexandria. The only answer was that the surface of the earth is curved. Not only

that, but the greater the curvature, the bigger the difference in the lengths of the shadows. The sun is so far away that

the shadows. The sun is so far away that its rays are parallel when they reach the earth. Sticks at different angles to

the earth. Sticks at different angles to the sun's rays will cast shadows of different lengths. For the observed

different lengths. For the observed difference in these shadow lengths, the distance between Alexandria and Sin had to be about 7° along the surface of the

earth. By that I mean if you imagine

earth. By that I mean if you imagine these sticks extending all the way down to the center of the earth, they would there intersect at an angle of about 7°.

Well, 7° is something like a 50th of the full circumference of the earth, 360°. Erosines knew the distance between

360°. Erosines knew the distance between Alexandria and Sin. He knew it was 800 km. Why? because he hired a man to pace

km. Why? because he hired a man to pace out the entire distance so that he could perform the calculation I'm talking

about. Now 800 km * 50 is 40,000 km. So

about. Now 800 km * 50 is 40,000 km. So

that must be the circumference of the earth. That's how far it is to go once

earth. That's how far it is to go once around the earth. That's the right answer. Erosines's only tools were

answer. Erosines's only tools were sticks, eyes, feet, and brains, plus a zest for

experiment. With those tools, he

experiment. With those tools, he correctly deduced the circumference of the Earth to high precision with an error of only a

few%. That's pretty good figuring for

few%. That's pretty good figuring for 2,200 years ago.

[Music] Then as now the Mediterranean was teeming with ships, merchant men, fishing vessels, naval flotillas, but

there were also courageous voyages into the unknown.

400 years before Aeritoines, Africa was circumnavigated by a Phoenician fleet in the employ of the Egyptian pharaoh Neco.

They set sail probably in boats as frail and open as these out from the Red Sea down the east coast of Africa up into the Atlantic and then back through the

Mediterranean. That epic journey took 3

Mediterranean. That epic journey took 3 years, about as long as it takes Voyager to journey from Earth to

Saturn. After Eerosines, some may have

Saturn. After Eerosines, some may have attempted to circumn the Earth, but until the time of Mellin, no one succeeded.

What tales of adventure and daring must earlier have been told as sailors and navigators, practical men of the world,

gambled their lives on the mathematics of a scientist from ancient Alexandria.

[Music] Today, Alexandria shows few traces of its ancient glory, of the days when Eratosines walked its broad avenues.

Over the centuries, waves of conquerors converted its palaces and temples into castles and churches, then into minouetses and

mosques. The city was chosen to be the

mosques. The city was chosen to be the capital of his empire by Alexander the Great on a winter's afternoon in 331 BC.

A century later, it had become the greatest city of the world. Each

successive civilization has left its [Music] mark. But what now remains of the marble

mark. But what now remains of the marble city of Alexander's dream? Alexandria's still a thriving

dream? Alexandria's still a thriving marketplace, still a crossroads for the peoples of the Near East.

[Music] [Laughter] [Music] But once it was radiant with

self-confidence, certain of its [Music] power. Can you recapture a vanished

power. Can you recapture a vanished epoch from a few broken statues and scraps of ancient manuscripts?

[Music] In Alexandria, there was an immense library and an associated research institute. And in them worked the finest

institute. And in them worked the finest minds in the ancient world.

[Music]

of that legendary library. All that

survives is this dank and forgotten cellar.

It's in the library annex, the Sarapam, which was once a temple but was later reconsecrated to

knowledge. These few moldering shelves,

knowledge. These few moldering shelves, probably once in a basement storage room, are its only physical

remains. But this place was once the

remains. But this place was once the brain and glory of the greatest city.

It was the first true research institute in the history of the world. And what

did they study? They studied everything.

The entire cosmos. Cosmos is a Greek word for the order of the universe. In a

way, it's the opposite of chaos. It

implies a deep interconnectedness of all things. Uh the intricate and subtle way

things. Uh the intricate and subtle way that the universe is put together. Genius flourished here. In

together. Genius flourished here. In

addition to Eerosineses, there was the astronomer Hipparus who mapped the constellations and established the brightness of the

stars. And there was Uklid who

stars. And there was Uklid who brilliantly systematized geometry who told his king who was struggling with some difficult problem in

mathematics that there was no royal road to geometry. There was Dionius of Thrace

to geometry. There was Dionius of Thrace the man who defined the parts of speech nouns verbs so on who did for language

in a way what Uklid did for geometry.

There was Herophilus, a physiologist who identified the brain rather than the heart as the seed of intelligence. There

was Archimedes, the greatest mechanical genius until the time of Leonardo da Vinci. And there was the astronomer

Vinci. And there was the astronomer Talamy who compiled much of what today is the pseudo science of astrology. His

earth centered universe held sway for 1500 years, showing that intellectual brilliance is no guarantee against being

dead wrong. And among these great men,

dead wrong. And among these great men, there was also a great woman. Her name

was Hipatia. She was a mathematician and a and an astronomer. The last light of the library whose martyrdom is bound up

with the destruction of this place seven centuries after it was founded.

[Music] Look at this

place. The Greek kings of Egypt who

place. The Greek kings of Egypt who succeeded Alexander regarded advances in science, literature, and medicine as among the treasures of the empire. For

centuries, they generously supported research and scholarship. An

enlightenment shared by few heads of state then are now.

Off this great hall were 10 large research laboratories. There were

research laboratories. There were fountains and colonades, botanical gardens, and even a zoo with animals from India and subsaharan Africa. There

were dissecting rooms and an astronomical observatory.

But the treasure of the library, consecrated to the god Sarapus, built in the city of Alexander, was its collection of books. The

organizers of the library combed all the cultures and languages of the world for books. They sent agents abroad to buy up

books. They sent agents abroad to buy up libraries. Commercial ships docking in

libraries. Commercial ships docking in Alexandria Harbor were searched by the police, not for contraband, but for books. The scrolls were borrowed,

books. The scrolls were borrowed, copied, and returned to their owners.

Until studied, these scrolls were collected in great stacks called books from the ships. Accurate numbers are difficult to come by, but it seems that

the library contained at its peak nearly 1 million scrolls.

[Music] [Applause] [Music] The papyrus reed grows in Egypt. It's

the origin of our word for paper. And

each of those million volumes which once existed in this library were handwritten on papyrus manuscript scrolls. What happened to all those

scrolls. What happened to all those books? Well, the classical civilization

books? Well, the classical civilization that created them disintegrated. The

library itself was destroyed. Only a

small fraction of the works survived.

And as for the rest, we are left only with pathetic scattered fragments. But

how tantalizing those remaining bits and pieces are. For example, we know that

pieces are. For example, we know that there once existed here a book by the astronomer Aristoarkus of Samos who

apparently argued that the Earth was one of the planets that like the other planets it orbits the sun and that the

stars are enormously far away. All

absolutely correct. But we had to wait nearly 2,000 years for these facts to be rediscovered.

[Music] The astronomy stacks of the Alexandria Library.

[Music] Eparosomeos. Here we

Eparosomeos. Here we are.

Arristos. This is the book. How I'd love to be able to read this book, to know how Aristarus figured it out, but it's

gone utterly and forever. If we multiply our sense of loss for this work of Aristoarkus by 100,000, we begin to appreciate the grandeur of the

achievement of classical civilization and the tragedy of its destruction.

[Music] We have far surpassed the science known to the ancient world, but there are irreparable gaps in our historical

knowledge. Imagine what mysteries of the

knowledge. Imagine what mysteries of the past could be solved with a borrower's card to this library. For example, we know of a three volume history of the

world, now lost, written by a Babylonian priest named Barosus.

Volume one dealt with the interval from the creation of the world to the great flood, a period that he took to be 432,000 years or about a 100 times

longer than the Old Testament chronology. What wonders were in the

chronology. What wonders were in the books of Barosis. But why have I brought you

Barosis. But why have I brought you across 2,000 years to the library of Alexandria? Because this was when and

Alexandria? Because this was when and where we humans first collected seriously and systematically the knowledge of the

world. This is the earth as Eerosineses

world. This is the earth as Eerosineses knew it. A tiny spherical world a float

knew it. A tiny spherical world a float in an immensity of space and time. We

were at long last beginning to find our true bearings in the cosmos.

The scientists of antiquity took the first and most important steps in that direction before their civilization fell apart. But after the dark ages, it was

apart. But after the dark ages, it was by and large the rediscovery of the works of these scholars done here that made the Renaissance possible and

thereby powerfully influenced our own culture. When in the 15th century Europe

culture. When in the 15th century Europe was at last ready to awaken from its long sleep, it picked up some of the

tools, the books, and the concepts laid down here more than a thousand years before. By 1600, the longforgotten ideas

before. By 1600, the longforgotten ideas of Arisarchus had been rediscovered.

Johannes Kepler constructed elaborate models to understand the motion and arrangement of the planets, the clockwork of the heavens. And at night he dreamt of

heavens. And at night he dreamt of traveling to the moon. His principal scientific tools

moon. His principal scientific tools were the mathematics of the Alexandrian library and an unswerving respect for

the facts, however disquing they might be. His story and the story of the

be. His story and the story of the scientists who came after him are also part of our voyage.

70 years later, the sun- centered universe of Aristocarkus and Capernicus was widely accepted in the Europe of the Enlightenment. The idea arose that the

Enlightenment. The idea arose that the planets were worlds governed by laws of nature and scientific speculation turned to the motions of the stars. The

clockwork in the heavens was imitated by the watchmakers of Earth. Precise

timekeeping permitted great sailing ship voyages of exploration and discovery which bound up the earth.

This was a time when free inquiry was valued once again.

[Music] 250 years later, the earth was all explored. New adventurers now look to

explored. New adventurers now look to the planets and the stars. The galaxies

were recognized as great aggregates of stars, island universes millions of light years away. In the 1920s,

astronomers had begun to measure the speeds of distant galaxies. Exposure.

What time is it? Uh

7:15. All right, lights out, please.

They found that the galaxies were flying away from one another. To the

astonishment of everyone, the entire universe was expanding. We had begun to plum the true

expanding. We had begun to plum the true depths of time and space.

The long collective enterprise of science has revealed a universe some 15 billion years old. The time since the

explosive birth of the cosmos, the big bang. The cosmic calendar compresses the

bang. The cosmic calendar compresses the local history of the universe into a single year. If the universe began on

single year. If the universe began on January 1st, it was not until May that the Milky Way formed. Other planetary systems may have

formed. Other planetary systems may have appeared in June, July, and August. But

our sun and Earth, not until midepptember. Life arose soon

midepptember. Life arose soon after. Everything humans have ever done

after. Everything humans have ever done occurred in that bright speck at the lower right of the cosmic calendar.

The Big Bang is at upper left in the first 2nd of January 1st. 15 billion

years later is our present time, the last second of December 31st. Every month is 1 and a4 billion

31st. Every month is 1 and a4 billion years long. Each day represents 40

years long. Each day represents 40 million years. Each second stands for

million years. Each second stands for some 500 years of our history. the

blinking of an eye in the drama of cosmic [Music] time. At this scale, the cosmic calendar

time. At this scale, the cosmic calendar is the size of a football field, but all of human history would occupy an area the size of my hand. We're just

beginning to trace the long and tortuous path which began with the primeval fireball and led to the condensation of matter gas dust stars galaxies and

at least in our little nook of the universe, planets and life, intelligence, and inquisitive men and women. We've emerged so recently that

women. We've emerged so recently that the familiar events of our recorded history occupy only the last seconds of the last minute of December 31st. Some

critical events for the human species, however, began much earlier. Minutes

earlier. So, we change our scale from months to minutes. Down here, the first humans made their debut around 10:30 p.m. on December 31st.

p.m. on December 31st.

And with the passing of every cosmic minute, each minute 30,000 years long, we began the arduous journey towards understanding where we live and who we

are.

11:46 only 14 minutes ago, humans have tamed fire.

11:5920, the evening of the last day of the cosmic year, the 11th hour, the 59th minute, the 20th second, the domestication of plants and animals

begins. An application of the human

begins. An application of the human talent for making tools.

115935 settled agricultural communities evolve into the first cities. We humans appear on the cosmic

cities. We humans appear on the cosmic calendar so recently that our recorded history occupies only the last few

seconds of the last minute of December 31st. In the vast ocean of time which

31st. In the vast ocean of time which this calendar represents, all our memories are

confined to this small square. Every

person we've ever heard of lived somewhere in there. All those kings and battles, migrations and inventions, wars and loves, everything in the history

books happens here in the last 10 seconds of the cosmic calendar. We on Earth have just awakened

calendar. We on Earth have just awakened to the great oceans of space and time from which we have emerged.

We are the legacy of 15 billion years of cosmic evolution. We have a choice. We can

evolution. We have a choice. We can

enhance life and come to know the universe that made us, or we can squander our 15 billionyear heritage in meaningless self-destruction.

What happens in the first second of the next cosmic year depends on what we do here and now with our intelligence and

our knowledge of the cosmos.

Heat. Heat.

[Music]