"If you wish to make an apple pie from scratch you must first invent the universe." "Thank you very much." "Suppose I cut a piece out of this apple pie." "Crumbly, but good." "And now suppose we cut this piece in half, or more or less." "And then cut this piece in half and keep going." "How many cuts before we get down to an individual atom?" "The answer is about 90 successive cuts." "Of course, this knife isn't sharp enough the pie is too crumbly and an atom is too small to see in any case." "But there is a way to do it." "It was here at Cambridge University in England that the nature of the atom was first understood in part by shooting pieces of atoms at atoms and seeing how they bounce off." "A typical atom is surrounded by a kind of cloud of electrons." "The electrons are electrically charged, as the name suggests and they determine the chemical properties of the atom." "For example, the glitter of gold or the transparency of the solid that's made from the atoms silicon and oxygen." "But deep inside the atom hidden far beneath the outer electron cloud is the nucleus, composed chiefly of protons and neutrons." "Atoms are very small." "100 million of them, end to end, would be about so big." "And the nucleus is 100,000 times smaller still." "Nevertheless, most of the mass in an atom is in the nucleus." "The electrons are by comparison just bits of moving fluff." "Atoms are mainly empty space." "Matter is composed chiefly of nothing." "When we consider cutting this apple pie, but down beyond a single atom we confront an infinity of the very small." "And when we look up at the night sky we confront an infinity of the very large." "These infinities are among the most awesome of human ideas." "They represent an unending regress which goes on not just very far, but forever." "Have you ever stood between two parallel mirrors in a barbershop, say and seen a very large number of you?" "Or you could use two flat mirrors and a candle flame you would see a large number of images each the reflection of another image." "You can't really see an infinity of images because the mirrors aren't perfectly flat and aligned." "And there's a candle or a candle flame in the way and light doesn't travel infinitely fast." "When we talk of real infinities we're talking about a quantity larger than any number." "No matter what number you have in mind, infinity is larger." "There's a nice way to write large numbers." "You can write the number 1000 as 10 to the power three meaning, a one followed by three zeros." "Or a million is written as 10 to the power six meaning, a one followed by six zeros." "There's no largest number." "If anybody gives you a candidate you can always add the number one to it." "But there certainly are very big numbers." "The American mathematician Edward Kasner once asked his nephew to invent a name for an extremely large number:" "10 to the power 100 which I can't write out all the zeros because there isn't room." "The boy called it a googol." "If you think a googol is large, consider a googolplex." "It's 10 to the power of a googol." "That is, a one followed, not by 100 zeros but by a googol zeros." "Now, by comparison with these enormous numbers the total number of atoms in that apple pie is only about 10 to the 26th." "Tiny compared to a googol and of course, much, much less than a googolplex." "The number of elementary particles protons, neutrons and electrons in the accessible universe is of the order of 10 to the 80th." "A one followed by 80 zeros." "Still much, much less than a googol and vastly less than a googolplex." "And yet, these numbers, the googol and the googolplex do not approach, they come nowhere near infinity." "In fact, a googolplex is precisely as far from infinity as is the number one." "We started to write out a googolplex but it wasn't easy." "SAGAN:" "It's a very big number." "Writing out a googolplex is a spectacularly futile exercise." "A piece of paper large enough to contain the zeros in a googolplex couldn't be stuffed into the known universe." "Fortunately there's a much simpler and more concise way to write a googolplex." "Like this." "And infinity can be represented like this." "This is the Cavendish Laboratory at Cambridge University where the constituents of the atom were first discovered." "The realm of the very small." "From the time of Democritus, in the fifth century B.C people have speculated about the existence of atoms." "For the last few hundred years, there have been persuasive but indirect arguments that all matter is made of atoms." "But only in our time, have we actually been able to see them." "Here the red blobs are the random throbbing motions of uranium atoms magnified 100 million times." "How Democritus of Abdera would've enjoyed this movie." "We pretty much take atoms for granted." "And yet, there are so many different kinds lovely and useful at the same time." "Look." "There are some 92 chemically distinct kinds of atoms naturally found on Earth." "They're called the chemical elements." "Virtually everything we see and know all the beauty of the natural world is made of these few kinds of atoms arranged in harmonious chemical patterns." "Here we've represented all 92 of them." "At room temperature, many of them are solids." "A few are gases." "And two of them bromine and mercury, are liquids." "They're arranged in order of complexity." "Hydrogen, the simplest element, is element number 1." "And uranium, the most complex is element 92." "Some elements are very familiar." "For example silicon, oxygen, magnesium, aluminum, iron those that make up the Earth." "Or hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur the elements that are essential for life." "Other elements are spectacularly unfamiliar." "For example, hafnium." "Erbium." "Dysprosium." "Praseodymium." "Elements we don't bump into in everyday life." "By and large, the more familiar an element is, the more abundant it is." "There's a great deal of iron on the Earth." "Not all that much yttrium." "The fact that atoms are composed of only three kinds of elementary particles protons, neutrons and electrons is a comparatively recent finding." "The neutron was not discovered until 1932." "And it, like the electron and the proton, were discovered here at Cambridge University." "Modern physics and chemistry have reduced the complexity of the sensible world to an astonishing simplicity." "Three units, put together in different patterns make, essentially, everything." "A neutron is electrically neutral as its name suggests." "A proton has a positive electrical charge and an electron an equal, negative electrical charge." "Since every atom is electrically neutral the number of protons in the nucleus must equal the number of electrons far away in the electron cloud." "The protons and neutrons, together, make up the nucleus of the atom." "Now, the chemistry of an atom, the nature of a chemical element depends only on the number of electrons which equals the number of protons, which is called the atomic number." "Chemistry is just numbers." "An idea which would have appealed to Pythagoras." "If you're an atom and you have just one proton you're hydrogen." "Two protons, helium." "Three, lithium." "Four, beryllium." "Five protons, boron." "Six, carbon, and seven, nitrogen." "Eight, oxygen, and so on." "All the way to 92 protons in which case your name is uranium." "Protons have positive electrical charges but like charges repel each other." "So why does the nucleus hold together?" "Why don't the electrical repulsion of the protons make the nucleus fly to pieces?" "Because there's another force in nature." "Not electricity, not gravity the nuclear force." "We can think of it as short-range hooks which start working when protons or neutrons are brought very close together." "The nuclear force can overcome the electrical repulsion of the protons." "Since the neutrons exert nuclear forces but not electrical forces they are a kind of glue which holds the atomic nucleus together." "A lump of two protons and two neutrons is the nucleus of a helium atom and is very stable." "Three helium nuclei, stuck together by nuclear forces makes carbon." "Four helium nuclei makes oxygen." "There's no difference between four helium nuclei stuck together by nuclear forces and the oxygen nucleus." "They're the same thing." "Five helium nuclei makes neon." "Six makes magnesium." "Seven makes silicon." "Eight makes sulfur, and so on." "Increasing the atomic numbers by two and always making some familiar element." "Every time we add or subtract one proton and enough neutrons to keep the nucleus together we make a new chemical element." "Consider mercury:" "If we subtract one proton from mercury and three neutrons, we convert it into gold." "The dream of the ancient alchemists." "Beyond element 92, beyond uranium there are other elements." "They don't occur naturally on the Earth." "They're synthesized by human beings and fall to pieces pretty rapidly." "One of them, element 94, is called plutonium and is one of the most toxic substances known." "Where do the naturally occurring chemical elements come from?" "Perhaps a separate creation for each element?" "But all the elements are made of the same elementary particles." "The universe, all of it, everywhere is 99.9% hydrogen and helium." "The two simplest elements." "In fact, helium was detected on the sun before it was ever found on the Earth." "Might the other chemical elements have somehow evolved from hydrogen and helium?" "To avoid the electrical repulsion protons and neutrons must be brought very close together so the hooks which represent nuclear forces are engaged." "This happens only at very high temperatures, where particles move so fast that there's no time for electrical repulsion to act." "Temperatures of tens of millions of degrees." "Such high temperatures are common in nature." "Where?" "In the insides of the stars." "Atoms are made in the insides of stars." "In most of the stars we see, hydrogen nuclei are being jammed together to form helium nuclei." "Every time a nucleus of helium is made, a photon of light is generated." "This is why the stars shine." "Stars are born in great clouds of gas and dust." "Like the Orion Nebula, 1500 light-years away parts of which are collapsing under gravity." "Collisions among the atoms heat the cloud until, in its interior hydrogen begins to fuse into helium and the stars turn on." "Stars are born in batches." "Later, they wander out of their nursery to pursue their destiny in the Milky Way." "Adolescent stars, like the Pleiades are still surrounded by gas and dust." "Eventually, they journey far from home." "Somewhere there are stars formed from the same cloud complex as the sun 5 billion years ago." "But we do not know which stars they are." "The siblings of the sun may, for all we know, be on the other side of the galaxy." "Perhaps they also warm nearby planets as the sun does." "Perhaps they too have presided over the evolution of life and intelligence." "The sun is the nearest star, a glowing sphere of gas shining because of its heat, like a red-hot poker." "The surface we see in ordinary visible light is at 6000 degrees centigrade." "But in its hidden interior in the nuclear furnace where sunlight is ultimately generated its temperature is 20 million degrees." "In x-rays we see a part of the sun that is ordinarily invisible its million-degree halo of gas the solar corona." "In ordinary visible light, these cooler, darker regions are the sunspots." "They are associated with great surges of flaming gas tongues of fire which would engulf the Earth if it were this close." "These prominences are guided into paths determined by the sun's magnetic field." "The dark regions of the x-ray sun are holes in the solar corona through which stream the protons and electrons of the solar wind on their way past the planets to interstellar space." "All this churning power is driven by the sun's interior which is converting 400 million tons of hydrogen into helium every second." "The sun is a great fusion reactor into which a million Earths would fit." "Luckily for us, it's safely placed 150 million kilometers away." "It is the destiny of stars to collapse." "Of the thousands of stars you see when you look up at the night sky every one of them is living in an interval between two collapses." "An initial collapse of a dark interstellar gas cloud to form the star and a final collapse of the luminous star on the way to its ultimate fate." "Gravity makes stars contract unless some other force intervenes." "The sun is an immense ball of radiating hydrogen." "The hot gas in its interior tries to make the sun expand." "The gravity tries to make the sun contract." "The present state of the sun is the balance of these two forces an equilibrium between gravity and nuclear fire." "In this long middle age between collapses the stars steadily shine." "But when the nuclear fuel is exhausted, the interior cools the pressure no longer supports its outer layers and the initial collapse resumes." "There are three ways that stars die." "Their fates are predestined." "Everything depends on their initial mass." "A typical star with a mass like the sun will one day continue its collapse until its density becomes very high." "And then the contraction is stopped by the mutual repulsion of the overcrowded electrons in its interior." "A collapsing star twice as massive as the sun isn't stopped by the electron pressure." "It goes on falling in on itself until nuclear forces come into play and they hold up the weight of the star." "But a collapsing star three times as massive as the sun isn't stopped even by nuclear forces." "There's no force known that can withstand this enormous compression." "And such a star has an astonishing destiny." "It continues to collapse until it vanishes utterly." "Each star is described by the force that holds it up against gravity." "A star that's supported by the gas pressure is a normal, run-of-the-mill star like the sun." "A collapsed star that's held up by electron forces is called a white dwarf." "It's a sun shrunk to the size of the Earth." "A collapsed star supported by nuclear forces is called a neutron star." "It's a sun shrunk to the size of a city." "And a star so massive that in its final collapse it disappears altogether is called a black hole." "It's a sun with no size at all." "But on their ways to their separate fates all stars experience a premonition of death." "Before the final gravitational collapse the star shudders and briefly swells into some grotesque parody of itself." "With its last gasp, it becomes a red giant." "Some 5 billion years from now there will be a last, perfect day on Earth." "Then, the sun will slowly change and the Earth will die." "There is only so much hydrogen fuel in the sun." "When it's almost all converted to helium the solar interior will continue its original collapse." "Higher temperatures in its core will make the outside of the sun expand and the Earth will become slowly warmer." "Eventually, life will be extinguished the oceans will evaporate and boil and our atmosphere will gush away to space." "The sun will become a bloated red giant star filling the sky enveloping and devouring the planets Mercury and Venus." "And probably the Earth as well." "The inner solar system will reside inside the sun." "But perhaps by then, our descendants will have ventured somewhere else." "In its final agonies, the sun will slowly pulsate." "By then, its core will have become so hot that it temporarily converts helium into carbon." "The ash from today's nuclear fusion will become the fuel to power the sun near the end of its life in its red giant stage." "Then the sun will lose great shells of its outer atmosphere to space filling the solar system with eerily glowing gas." "The ghost of a star, outward bound." "Perhaps half the mass of the sun will be lost in this way." "Viewed from elsewhere, our system will then resemble the Ring Nebula in Lyra the atmosphere of the sun expanding outward like a soap bubble." "And at the very center will be a white dwarf." "The hot exposed core of the sun its nuclear fuel now exhausted, slowly cooling to become a cold, dead star." "Such is the life of an ordinary star." "Born in a gas cloud, maturing as a yellow sun decaying as a red giant and dying as a white dwarf enveloped in its shroud of gas." "Suppose, as we traveled through interstellar space in our ship of the imagination we could sample the cold, thin gas between the stars." "We would find a great preponderance of hydrogen an element as old as the universe." "We would find carbon, oxygen, silicon." "The most abundant atoms in the cosmos, apart from hydrogen are those most easily made in the stars." "But we would also find a small proportion of rare elements." "Praseodymium, say, or gold." "They're not made in red giants." "Such elements are manufactured in one of the most dramatic gestures of which a star is capable." "A star more than about one and a half times the mass of the sun cannot become a white dwarf." "It will end its life by blowing itself up in a titanic stellar explosion called a supernova." "There has been no supernova explosion in our province of the galaxy since the telescope's invention and our sun will not become a supernova." "But in our imagination we can fulfill the dream of many earthbound astronomers and safely witness, close-up, a supernova explosion." "Most of stellar evolution takes millions or billions of years." "But the interior collapse that triggers a supernova explosion takes only seconds." "The star becomes brighter than all the other stars in the galaxy put together." "If a nearby star became a supernova it would be calamity enough for the inhabitants of this alien system." "But if their own sun went supernova it would be an unprecedented catastrophe." "Worlds would be charred and vaporized." "Life, even on the outer planets, would be extinguished." "In our ship of the imagination, we are now backing away from the star." "But the explosion fragments traveling almost at the speed of light, are overtaking us." "Individual atomic nuclei, accelerated to high speeds in the explosion become cosmic rays." "This is another way that stars return the atoms they've synthesized back into space." "The shock wave of expanding gases heats and compresses the interstellar gas triggering a later generation of stars to form." "In this sense also stars are phoenixes rising from their own ashes." "The cosmos was originally all hydrogen and helium." "Heavier elements were made in red giants and in supernovas and then blown off to space where they were available for subsequent generations of stars and planets." "Our sun is probably a third-generation star." "Except for hydrogen and helium every atom in the sun and the Earth was synthesized in other stars." "The silicon in the rocks, the oxygen in the air, the carbon in our DNA the gold in our banks, the uranium in our arsenals were all made thousands of light-years away and billions of years ago." "Our planet, our society and we ourselves are built of star stuff." "We're in a lava tube." "A cave carved through the Earth by a river of molten rock." "To do a little experiment we've brought a Geiger counter and a piece of uranium ore." "The Geiger counter is sensitive to high-energy charged particles protons, helium nuclei, gamma rays." "If we bring it close to the uranium ore the count rate, the number of clicks, increases dramatically." "We also have a lead canister here." "And if I drop the uranium ore into the canister, which absorbs the radiation, and cover it up I then find the count-rate goes down substantially but it doesn't go down to zero." "What's the source of the remaining counts?" "Some of them come from radioactivity in the walls of the cave." "But there's more to it than that." "Some of the counts are due to high-energy charged particles which are penetrating the roof of the cave." "We are listening to cosmic rays." "Every second they are penetrating my body and yours." "They don't do much damage." "Cosmic rays have bombarded the Earth for the entire history of life on our planet." "But they do cause some mutations and they do affect life on the Earth." "The cosmic rays, mainly protons are penetrating through the meters of rock in the cave above me." "To do this, they have to be very energetic and in fact they are traveling almost at the speed of light." "Think of it." "A star blows up thousands of light-years away in space and produces cosmic rays which spiral through the Milky Way galaxy for millions of years until, quite by accident some of them strike the Earth penetrate this cave, reach this Geiger counter and us." "The evolution of life on Earth is driven in part through mutations by the deaths of distant stars." "We are, in a very deep sense tied to the cosmos." "Our ancestors knew this well." "The movements of the sun, the moon, and the stars could be used by those skilled in such arts to foretell the seasons." "So the ancient astronomers all over the world studied the night sky with care memorizing and recording the position of every visible star." "To them, the appearance of any new star would have been significant." "What would they have made of the apparition of a supernova brighter than every other star in the sky?" "On July 4th, in the year 1054 Chinese astronomers recorded what they called a guest star in the constellation of Taurus the Bull." "A star never before seen burst into radiance became almost as bright as the full moon." "Halfway around the world, here in the American Southwest there was then a high culture, rich in astronomical tradition." "They too must have seen this brilliant new star." "From carbon-14 dating of the remains of a charcoal fire, we know that in this very spot there were people living in the 11th century." "The people were the Anasazi, the antecedents of the Hopi of today." "And one of them seems to have drawn on this overhang, protected from the weather a picture of the new star." "Its position near the crescent moon would have been just what we see here." "And the handprint is, perhaps the artist's signature." "This remarkable star is now called the Crab Supernova." ""Nova" from the Latin word for new and "Crab" because that's what an astronomer centuries later was reminded of when looking at this explosion or remnant through the telescope." "The Crab is a star that blew itself up." "The explosion was seen for three months." "It was easily visible in broad daylight." "And you could read by it at night." "Imagine the night when that colossal stellar explosion first burst forth." "A thousand years ago people gazed up in amazement at the brilliant new star and wondered what it was." "We are the first generation privileged to know the answer." "Through the telescope we have seen what lies today at the spot in the sky noted by the ancient astronomers." "A great luminous cloud, the remains of a star violently unraveling itself back into interstellar space." "Only the massive red giants become supernovas." "But every supernova was once a red giant." "In the history of the galaxy hundreds of millions of red giants have become supernovas." "The bit of the star that isn't blown away collapses under gravity spinning ever faster like a pirouetting ice skater bringing in her arms." "The star becomes a single, massive atomic nucleus a neutron star." "The one in the Crab Nebula is spinning 30 times a second." "It emits a beamed pattern of light and seems to us to be blinking on and off with astonishing regularity." "Such neutron stars are called pulsars." "Neutron star matter weighs about a mountain per teaspoonful." "So much that if I had a piece of it here and let it go I could hardly prevent it from falling." "It would effortlessly pass through the Earth like a a knife through warm butter." "It would carve a hole for itself completely through the Earth emerging out the other side perhaps in China." "The people there might be walking along when a tiny lump of neutron star matter comes booming out of the ground and then falls back again." "The incident might make an agreeable break in the routine of the day." "The neutron star matter, pulled back by the Earth's gravity would plunge again through the Earth eventually punching hundreds of thousands of holes before friction with the interior of our planet stopped the motion." "By the time it's at rest at the center of the Earth the inside of our world would look a little bit like Swiss cheese." "There are places in the galaxy where a neutron star and a red giant are locked in a mutual gravitational embrace." "Tendrils of red giant star stuff spiral into a disc of accreting matter centered on the hot neutron star." "Every star exists in a state of tension between the force that holds it up and gravity, the force that would pull it down." "If gravity were to prevail, a stellar madness would ensue more bizarre than anything in wonderland." "Alice and her colleagues feel, more or less at home in the gravitational pull of the Earth called one g, "g" for Earth gravity." "What would happen if we made the gravity less, or more?" "At lower gravity, things get lighter." "Near zero g, the slightest motion sends our friends floating and tumbling in the air." "Little blobs of liquid tea are everywhere." "Curious." "If we now return the gravity to one g it's raining tea, and our friends fall back to Earth." "I've been to a couple of parties like that myself." "At higher gravities, two or three g's, say, things get really laid back." "Everyone feels heavy and leaden." "Except by special dispensation the Cheshire cat." "As a kindness, we remove them." "At thousands of g's, trees become squashed." "At 100,000 g's, rocks become crushed by their own weight." "At all these gravities, a beam of light remains unaffected continuing up in a straight line." "But at billions of g's a beam of light feels the gravity and begins to bend back on itself." "Curiouser and curiouser." "Such a place, where the gravity is so large that even light can't get out is called a black hole." "It's a star in which light itself is imprisoned." "Black holes were theoretical constructs speculated about since 1783." "But in our time, we've verified the invisible." "This bright star has a massive, unseen companion." "Satellite observatories find the companion to be an x-ray source called Cygnus X-1." "These x-rays are like the footprints of an invisible man walking in the snow." "The x-rays are thought to be generated by friction in the accretion disc surrounding the black hole." "The matter in the disc slowly disappears down the black hole." "Massive black holes, produced by the collapse of a billion suns may be sitting at the centers of other galaxies curiously producing great jets of radiation pouring out into space." "At high enough density, the star winks out and vanishes from our universe leaving only its gravity behind." "It slips through a self-generated crack in the space-time continuum." "A black hole is a place where a star once was." "Here we have a flat two- dimensional surface with grid lines on it, something like a piece of graph paper." "Suppose we take a small mass drop it on the surface and watch how the surface distorts or puckers into the third physical dimension." "Gravity can be understood as a curvature of space." "If our moving ball approaches a stationary distortion it rolls around it like a planet orbiting the sun." "In this interpretation, due to Einstein, gravity is only a pucker in the fabric of space which moving objects encounter." "Space is warped by mass into an additional physical dimension." "The larger the local mass, the greater is the local gravity and the more intense is the distortion or pucker, or warp of space." "So, by this analogy a black hole is a kind of bottomless pit." "What would happen if you fell in?" "Assuming you could survive the gravitational tides and the intense radiation flux, it is just barely possible that by plunging into a black hole you might emerge in another part of space-time." "Somewhere else in space some-when else in time." "In this view, space is filled with a network of wormholes something like the wormholes in an apple." "Although by no means is this point demonstrated it is merely an exciting suggestion." "If it is true then perhaps there exist gravity tunnels a kind of interstellar or intergalactic subway which would permit you to get from here to there in much less than the usual time." "A kind of cosmic rapid transit system." "We cannot generate black holes our technology is far too feeble to move such massive amounts of matter around." "But perhaps someday, it will be possible to voyage hundreds or thousands of light-years to a black hole like Cygnus X-1." "We would plunge down to emerge in some unimaginably exotic time and place." "Our common-sense notions of reality severely challenged." "Perhaps the cosmos is infested with wormholes every one of them a tunnel to somewhere." "Perhaps other civilizations, with vastly more advanced technologies are today riding the gravity express." "It's even possible that a black hole is a gate to another, and quite different, universe." "The lives and deaths of the stars seem impossibly remote from human experience and yet we're related in the most intimate way to their life cycles." "The very matter that makes us up was generated long ago and far away in red giant stars." "A blade of grass, as Walt Whitman said..." ""...is the journey work of the stars."" "The formation of the solar system may have been triggered by a nearby supernova explosion." "After the sun turned on its ultraviolet light poured into our atmosphere." "Its warmth generated lightning." "And these energy sources sparked the origin of life." "Plants harvest sunlight converting solar into chemical energy." "We and the other animals are parasites on the plants." "So we are, all of us, solar-powered." "The evolution of life is driven by mutations." "They are caused partly by natural radioactivity and cosmic rays." "But they are both generated in the spectacular deaths of massive stars thousands of light-years distant." "Think of the sun's heat on your upturned face on a cloudless summer's day." "From 150 million kilometers away we recognize its power." "What would we feel on its seething, self-luminous surface or immersed in its heart of nuclear fire?" "And yet, the sun is an ordinary, even a mediocre star." "Our ancestors worshiped the sun and they were far from foolish." "It makes good sense to revere the sun and the stars." "Because we are their children." "We have witnessed the life cycles of the stars." "They are born, they mature and then they die." "As time goes on, there are more white dwarfs more neutron stars, more black holes." "The remains of the stars accumulate as the eons pass." "But interstellar space also becomes enriched in heavy elements out of which form new generations of stars and planets life and intelligence." "The events in one star can influence a world halfway across the galaxy and a billion years in the future." "The vast interstellar clouds of gas and dust are stellar nurseries." "Here first begins the inexorable gravitational collapse which dominates the lives of the stars." "Massive suns may evolve through the red giant stage in only millions of years." "Dying young, never leaving the cloud in which they were born." "Other suns, longer-lived, wander out of the nursery." "Our sun is such a star as are most of the stars in the sky." "Most stars are members of double or multiple star systems and live to process their nuclear fuel over billions of years." "The galaxy is 10 billion years old." "Old enough to have spawned only a few generations of ordinary stars." "The objects we encounter in a voyage through the Milky Way are stages in the life cycle of the stars." "Some are bright and new and others are as ancient as the galaxy itself." "Surrounding the Milky Way is a halo of matter which includes the globular clusters each containing up to a million elderly stars." "At the centers of globular clusters and at the core of the galaxy there may be massive black holes ticking and purring the subject of future exploration." "We on Earth marvel, and rightly so at the daily return of our single sun." "But from a planet orbiting a star in a distant globular cluster a still more glorious dawn awaits." "Not a sunrise, but a galaxy-rise." "A morning filled with 400 billion suns the rising of the Milky Way." "An enormous spiral form with collapsing gas clouds condensing planetary systems, luminous supergiants stable middle-aged stars red giants, white dwarfs, planetary nebulas, supernovas neutron stars, pulsars, black holes and there is every reason to think, other exotic objects that we have not yet discovered." "From such a world, high above the disc of the Milky Way it would be clear as it is beginning to be clear on our world that we are made by the atoms in the stars that our matter and our form are determined by the cosmos of which we are a part." "I only have a moment, but I wanted you to see a picture of Betelgeuse in the constellation Orion." "The first image of the surface of another star." "But the most exciting recent stellar discovery has been of a nearby supernova in a companion galaxy to the Milky Way." "We are here seeing chemical elements in the process of synthesis and have had our first glimpse of the supernova through a brand-new field:" "neutrino astronomy." "And we're now seeing, around neighboring stars discs of gas and dust just like those needed to explain the origin of the planets in our solar system." "Worlds may be forming here." "It's like a snapshot of our solar system's past." "And there are so many such discs being found these days that planets may be very common among the stars of the Milky Way." "(HEART BEATING)" "SAGAN:" "There is one experience that every human shares of every language and culture:" "The experience of birth." "Our recollections of birth are hazy at best." "They have the feel and aura not so much of memories as of mystical transfigurations." "It would be astonishing if this profound early experience did not influence our myths and religions our philosophy and our science." "The birth of a child evokes the mystery of other origins the beginnings and ends of worlds infinity and eternity." "How did the universe arise?" "What was around before that?" "Might there have been no beginning?" "Could the universe be infinitely old?" "Are there boundaries to the cosmos?" "The current scientific story of the origin of the universe begins with an explosion which made space itself expand." "About 15 billion years ago all the matter and energy that make up the observable universe were concentrated into a space smaller than the head of a pin." "The cosmos blew apart in one inconceivably colossal explosion:" "The big bang." "The stuff of the universe, together with the fabric of space itself began expanding in all directions as they do today." "We can visualize this process with a three-dimensional grid attached to the expanding fabric of space." "The early cosmos was everywhere white-hot." "But as time passed, the radiation expanded and cooled and in ordinarily visible light, space became dark as it is today." "But then little pockets of gas began to grow." "Tendrils of gossamer clouds formed colonies of great, lumbering, slowly spinning things steadily brightening, each a kind of beast..." "The largest recognizable structures in the universe had formed." "We see them today." "We ourselves inhabit some lost corner of one." "We call them the galaxies." "We inhabit a universe of galaxies." "There are unstructured blobs, the irregular galaxies globular or elliptical galaxies and the graceful blue arms of spiral galaxies." "We've been investigating the galaxies their origins, evolution and motions for less than a century." "These studies extend our understanding to the farthest reaches of the universe." "Our ship of the imagination carries us to that ultimate frontier." "We view the cosmos on the grandest of scales." "The majesty of the galaxies is revealed by science." "There are many different ways in which stars are arrayed into galaxies." "When, by chance, the face of a spiral galaxy is turned toward us we see the spiral arms, made luminous by billions of stars." "When, in other cases, the edge of a galaxy is towards us we see the central lanes of gas and dust from which the stars are forming." "In barred spirals, a river of star stuff extends through the galactic center connecting opposite spiral arms." "Elliptical galaxies come in giant and dwarf sizes." "There are many mysterious galaxies places where something has gone terribly wrong where there are explosions and collisions and streamers of gas and stars bridges between the galaxies." "The galaxies look rigid, unmoving." "But we see them only for a single frame of the cosmic movie." "Their parts are dissipating and reforming on a time scale of hundreds of millions of years." "A galaxy is a fluid made of billions of suns all bound together by gravity." "These giant galactic forms exist throughout the universe and may be a common source of wonderment and instruction for billions of species of intelligent life." "Their evolution is governed everywhere by the same laws of physics." "We need a computer to illustrate the collective motion of so many stars each under the gravitational influence of all the others." "A billion years is here compressed into a few seconds." "In some cases, spiral arms form all by themselves." "In other cases the close gravitational encounter of two galaxies will draw out spiral arms." "But when two nearby galaxies collide like a bullet through a swarm of bees the stars hardly collide at all." "But the shapes of the galaxies can be severely distorted." "A direct collision of two galaxies can last a hundred million years and spill the constituent stars careening through intergalactic space." "When a dense, compact galaxy runs into a larger one face-on it can produce one of the loveliest of the rare irregulars:" "A ring galaxy." "Thousands of light-years across a ring galaxy is set against the velvet of intergalactic space." "It's a temporary configuration of disrupted stars a splash in the cosmic pond." "Galaxies sometimes blow themselves up." "The quasars, probably billions of light-years away may be the colossal explosions of young galaxies." "But we're not sure." "Quasars are a mystery still." "The galaxies reveal a universal order, beauty but also violence on a scale never before imagined." "The universe seems neither benign nor hostile merely indifferent to the concerns of such creatures as we." "Quasars may be monster versions of rapidly rotating pulsars or due to multiple collisions of millions of stars densely packed in the galactic core or a chain reaction of supernova explosions in such a core." "Some astronomers think a quasar is caused by millions of stars falling into an immense black hole in the core of a galaxy." "Something like a black hole something very massive, very dense and very small is ticking and purring away in the cores of nearby galaxies." "Even a well-behaved galaxy like the Milky Way has its stirrings and its dances." "The stars of the Milky Way move with systematic grace." "The sun takes 250 million years to go once around the core." "The outer provinces of the galaxy revolve more slowly than the inner regions." "As a result, gas and dust pile up in spiral patterns." "These places of greater density are where young, hot, bright stars form the stars which outline the spiral arms." "These hot stars shine for only 10 million years or so and then blow up." "But as the stars which outline a spiral arm burn out new, young stars are formed from the debris just behind them and the spiral pattern persists." "The sun, marked here with a circle has been in and out of spiral arms often in the 20 times it has gone around the Milky Way." "In this epoch, we live at the edge of a spiral arm." "We've looked at internal galactic motion on a small scale across a million light-years or less." "But the motion of the galaxies themselves across billions of light-years is different." "That motion is a relic of the big bang." "The key to cosmology, the study of the entire universe turns out to be a commonplace of nature an experience of everyday life." "Imagine a moving object sending out waves." "It could be light waves... (WHISTLE BLOWS) ...it could be sound waves, it could be any kind of wave." "When that moving object passes us we sense a change in pitch." "That's called the Doppler effect." "If you're the engineer in the cab the pitch of the whistle always sounds the same to you." "That's because you're moving along with the source of the sound." "But if you're standing alongside the track when the train passes you hear that familiar shift in pitch:" "The Doppler shift." "The reason this happens is easy to understand once you visualize the waves." "A stationary train sends out sound waves in perfect circles like the ripples on a pond." "Let's start the train again." "Now, the waves spreading out ahead of it get squashed together and those spreading out behind it get stretched apart." "The compressed waves have a higher frequency or pitch than the stretched-out waves." "The same thing is true for light waves." "Color is to light precisely what pitch is to sound." "Compressed light waves are made bluer." "They're blue-shifted." "Stretched-out light waves are made redder." "They're red-shifted." "At the speed of a train you can sense the change of pitch for sound, but not for light." "The train is traveling about a million times too slow for that." "It turns out that the Doppler effect for light waves is the key to the cosmos." "The evidence for this was gathered unexpectedly by a former mule-team driver who never went beyond the eighth grade." "During the second decade of this century the world's largest telescope was being assembled on Mount Wilson overlooking what were then the clear skies of Los Angeles." "Large pieces of the telescope were hauled to the mountaintop a job for mule teams." "One of the drivers was a young man named Milton Humason the ne'er-do-well son of a California banker." "But he was bright and naturally curious about the equipment he had carted up Mount Wilson." "And after the telescope was completed in 1917 he managed to stay on here as janitor and electrician." "One evening, so the story goes, the observatory night assistant was ill." "Humason was asked to fill in." "Humason was a gambling man celebrated for his skill at poker and at the pool table." "But his touch with the telescope was admired even more." "He discovered he had a talent for using astronomical instruments." "He became the virtuoso of the 100-inch telescope." "In this instrument, light from distant galaxies is focused on a glass photographic plate by a great encased mirror 100 inches across." "By the late 1920s, Humason was making observations himself." "Mr. Nelson?" "NELSON:" "I'm in the coudé room, sir." "SAGAN:" "Humason by now had his own night assistant to help him with the observations." "HUMASON:" "Afternoon, Mr. Nelson." "Good afternoon, Mr. Humason." "We'll start at 6." "I'll be making a spectrogram at the Cassegrain focus." "Yes, sir." "SAGAN:" "The telescope must be able to point with high accuracy to a designated region of the sky, and to keep on pointing there." "A machine weighing about 75 tons, as massive as a locomotive must move with a precision greater than that of the finest pocket watch." "Everything must be checked thoroughly." "The electrical power system must work flawlessly." "Hours before observations are to begin, the dome is opened to allow the temperature inside and outside to be equalized." "Humason prepared the sensitive photographic emulsions sheathed in their metal holders to capture with the giant telescope the faint light from remote galaxies." "This was part of a systematic program which Humason and his mentor, the astronomer Edwin Hubble were pursuing to measure the Doppler shift of light from the most distant galaxies then known." "But the most distant galaxies are very faint." "That's why even with the largest telescope in the world it was necessary to take very long time exposures often lasting all night and sometimes requiring several successive nights." "Humason would give the night assistant the celestial coordinates of the target galaxy." "Through the long, cold night, he'd have to make fine adjustments so the telescope would precisely track the target galaxy." "The galaxy itself was too faint to see through the telescope although it could be recorded photographically with a long time exposure." "So the telescope would be pointed at a nearby bright star and then offset to a featureless patch of sky from which, over the long night the light from the unseen galaxy would slowly accumulate." "The telescope focused the faint light from a galaxy into the spectrometer where it was spread out into its rainbow of constituent colors." "The spectrum would be recorded on the little glass plates." "Would you clamp in the drive and slue to the focus star, please?" "Are you clear?" "NELSON:" "I'm going to slue to the east." "Yes." "I think I'm clear." "HUMASON:" "Just take it easy." "All right, I have it." "Now, let's go to NGC 7-6-1-9." "I'm clear." "Going to do a 10-hour exposure." "What time is it?" "7:15." "HUMASON:" "Lights out, please." "The dark slide is open." "SAGAN:" "A large telescope views only a tiny patch of sky." "As the Earth turns, a guide star or a galaxy would drift out of the telescope's field of view in only a few minutes." "Humason had to stay awake, tracking the galaxy while elaborate machinery moved the telescope slowly in the opposite direction, to compensate for Earth's rotation." "The telescope is a kind of clock." "HUMASON:" "How's the dome?" "You're clear." "SAGAN:" "This work was difficult, routine, tedious but although they didn't yet know it Hubble and Humason were meticulously accumulating the evidence for the big bang." "They had found that the more distant the galaxy the more its spectrum of colors was shifted to the red." "HUMASON:" "All right, clear the telescope." "I'm coming down now." "If this red shift were due to the Doppler effect the distant galaxies must be running away from us." "At the end of his vigil Humason would retrieve the tiny galactic spectrum and carefully carry it down to be developed." "Thank you, Mr. Nelson." "I'm going to the darkroom now." "Good day." "Good day, sir." "In this way Humason found a red shift in almost every galaxy he examined like the Doppler shift in the sound of a receding locomotive." "And the farther away from us they were, the faster they were receding." "Tied to the fabric of space, the outward rushing galaxies were tracing the expansion of the universe itself." "An awesome conclusion had been captured on these tiny glass slides." "Humason and Hubble had discovered the big bang." "At top and bottom are calibration lines that Humason had earlier photographed." "In the middle is the spectrum of a relatively nearby galaxy." "Every element has a characteristic spectral fingerprint a set of frequencies where light is absorbed." "Prominent here are two dark lines in the violet due to calcium in the atmospheres of the hundreds of billions of stars that constitute this galaxy." "Nearby galaxies show very little Doppler shift." "But when he recorded the spectrum of a fainter and more distant galaxy he found the same telltale pair of lines but shifted farther right toward the red." "And when he examined a remote galaxy 4 billion light-years away he found the lines were red-shifted even more." "This galaxy must be receding at 200 million kilometers an hour." "The painstaking observations of Milton Humason astronomer and former mule-team driver established the expansion of the universe." "In discussing the large-scale structure of the cosmos astronomers sometimes say that space is curved or that the universe is finite but unbounded." "Whatever are they talking about?" "Let's imagine that we are perfectly flat I mean, absolutely flat and that we live, appropriately enough, in Flatland a land designed and named by Edwin Abbott a Shakespearean scholar who lived in Victorian England." "Everybody in Flatland is, of course, exceptionally flat." "We have squares, circles, triangles and we all scurry about and we can go into our houses and do our flat business." "Now, we have width and length but no height at all." "These cutouts have some height, but let's ignore that." "Let's imagine that these are absolutely flat." "That being the case, we know, us Flatlanders about left-right and about forward-back but we have never heard of up-down." "Let us imagine that into Flatland hovering above it which, oddly enough, looks like an apple." "The three-dimensional creature sees an attractive congenial-looking square watches it enter its house and decides in a gesture of inter-dimensional amity to say hello." ""Hello," says the three-dimensional creature." ""How are you?" "I am a visitor from the third dimension."" "Well, the poor square looks around his closed house sees no one there and what's more, has witnessed a greeting coming from his insides:" "A voice from within." "He surely is getting a little worried about his sanity." "The three-dimensional creature is unhappy about being considered a psychological aberration and so he descends to actually enter Flatland." "Now, a three-dimensional creature exists in Flatland only partially only a plane, a cross section through him can be seen." "So when the three-dimensional creature first reaches Flatland only its points of contact can be seen." "And we'll represent that by stamping the apple in this ink pad and placing that image in Flatland." "And as the apple were to descend through slither by Flatland we would progressively see higher and higher slices which we can represent by cutting the apple." "So the square, as time goes on sees a set of objects mysteriously appear from nowhere, and inside a closed room and change their shape dramatically." "His only conclusion could be that he's gone bonkers." "Well, the apple might be a little annoyed at this conclusion and so not such a friendly gesture from dimension to dimension makes a contact with the square from below and sends our flat creature fluttering and spinning above Flatland." "At first, the square has no idea what's happening." "He's terribly confused." "This is utterly outside his experience." "But after a while, he comes to realize that he is seeing inside closed rooms in Flatland." "He is looking inside his fellow flat creatures:" "He is seeing Flatland from a perspective no one has ever seen it before, to his knowledge." "Getting into another dimension provides, as an incidental benefit a kind of x-ray vision." "Now our flat creature slowly descends to the surface and his friends rush up to see him." "From their point of view, he has mysteriously appeared from nowhere." "He hasn't walked from somewhere else." "He's come from some other place." "They say, "For heaven's sake, what's happened to you?"" "And the poor square has to say:" ""Well, I was in some other mystic dimension called 'Up."'" "And they will pat him on his side and comfort him or else they'll ask:" ""Well, show us." "Where is that third dimension?" "Point to it."" "And the poor square will be unable to comply." "But maybe more interesting is the other direction in dimensionality." "What about the fourth dimension?" "Now, to approach that, let's consider a cube." "We can imagine a cube in the following way:" "Take a line segment and move it at right angles to itself in equal length." "That makes a square." "Move that square in equal length at right angles to itself and you have a cube." "Now, this cube, we understand casts a shadow." "And that shadow we recognize..." "It's, you know, ordinarily drawn in third-grade classrooms as two squares with their vertices connected." "If we look at a three-dimensional object's shadow in two dimensions we see that, in this case, not all the lines appear equal." "Not all the angles are right angles." "The 3-D object hasn't been perfectly represented in its projection in two dimensions." "But that's part of the cost of losing a dimension in the projection." "Now, let's take this three-dimensional cube and project it, carry it through a fourth physical dimension:" "Not that way, not that way, not that way." "But at right angles to those three directions." "I can't show you that direction." "But imagine that there is a fourth physical dimension." "In that case, we would generate a four-dimensional hyper-cube which is also called a tesseract." "I cannot show you a tesseract because I and you are trapped in three dimensions." "But what I can show you is the shadow in three dimensions of a four-dimensional hyper-cube or tesseract." "This is it, and you can see its two nested cubes all the vertices connected by lines." "And now the real tesseract in four dimensions would have all lines of equal length and all angles right angles." "That's not what we see here, but that's the penalty of projection." "So you see, while we cannot imagine the world of four dimensions we can certainly think about it perfectly well." "Now, imagine a universe just like Flatland truly two-dimensional and entirely flat in every direction." "But with one exception:" "Unbeknownst to the inhabitants their two-dimensional universe is curved into a third physical dimension." "Maybe into a sphere, but at any rate into something entirely outside their experience." "Locally, their universe still looks flat enough." "But if one of them, much smaller and flatter than me takes a very long walk along what seems to be a straight line he would uncover a great mystery." "Suppose he marked his starting point here and set off to explore his universe." "He never turns around and he never reaches an edge." "He doesn't know that his apparently flat universe is actually curved into an enormous sphere." "He doesn't sense that he's walking around a globe." "Why should his space be curved?" "Because this universe has so much matter that it gravitationally warps space closing it back on itself into a sphere." "But our Flatlander doesn't know this." "After a long while, he'll find he somehow returns to his starting point." "There must be a third dimension." "Our Flatlander couldn't imagine a third dimension but he could sure deduce it." "Increase all the dimensions in this story by one and you have something like the situation which many cosmologists think may actually apply to us." "We are three-dimensional creatures trapped in three dimensions." "We imagine our universe to be flat in three dimensions but maybe it's curved into a fourth." "We can talk about a fourth physical dimension, but we can't experience it." "No one can point to the fourth dimension." "There's left-right and there's forward-back." "There's up-down and there's some other directions simultaneously at right angles to those familiar three dimensions." "Now, imagine this universe is expanding." "If we blow it up like a four- dimensional balloon, what happens?" "An astronomer on a given galaxy thinks all the other galaxies are running away from him." "The more distant the galaxy, the faster it seems to be moving." "This is just what Humason and Hubble found." "On the surface of this curved universe, there is no boundary or center." "The universe can be both finite and unbounded." "The red shift of the distant galaxies seemed to imply to Humason's contemporaries that we were at the center of an expanding universe that our place in space was somehow privileged." "But if the universe is expanding whether or not it's curved into a fourth dimension observers on every galaxy will see precisely the same thing:" "All the galaxies rushing away from them as if they had made some dreadful intergalactic social blunder." "If there's enough matter to close the universe gravitationally then it's wrapped in on itself like a sphere." "If there isn't enough matter to close the cosmos then our universe has an open shape extending forever in all directions." "This saddle universe is only one of an infinite number of possible kinds of open universes." "Unlike such closed universes as the sphere open universes have in them an infinite amount of space." "If our universe is, in fact, closed off then nothing can get out, not matter, not light." "We would then be living inside a black hole." "There is one possible way out, though:" "A hypothetical tunnel or wormhole through the next higher dimension a place sucking in matter and light." "Can we find such a wormhole?" "Could we survive the trip?" "We might emerge in some other place and time perhaps in another universe or perhaps somewhere else in our own." "If you want to know what it's like inside a black hole look around." "But we don't yet know whether the universe is open or closed." "More than that, some astronomers doubt that the red shift of distant galaxies is due to the Doppler effect." "They are skeptical about the expanding universe and the big bang." "Perhaps our descendants will regard our present ignorance with as much sympathy as we feel to the ancients for not knowing whether the Earth went around the sun." "If the general picture, however, of a big bang followed by an expanding universe is correct what happened before that?" "Was the universe devoid of all matter and then the matter suddenly somehow created?" "How did that happen?" "In many cultures, the customary answer is that a god or gods created the universe out of nothing." "But if we wish to pursue this question courageously we must, of course, ask the next question:" "Where did God come from?" "If we decide that this is an unanswerable question why not save a step and conclude that the origin of the universe is an unanswerable question?" "Or if we say that God always existed why not save a step and conclude that the universe always existed?" "There's no need for a creation." "It was always here." "These are not easy questions." "Cosmology brings us face to face with the deepest mysteries with questions that were once treated only in religion and myth." ""Who knows for certain?" "Who shall here declare it?" "Whence was it born?" "Whence came creation?" "The gods are later than this world's formation." "Who then can know the origins of the world?" "None knows whence creation arose or whether He has or has not made it He who surveys it from the lofty skies." "Only He knows or perhaps He knows not."" "These words are 3500 years old." "They're taken from the Rig-Veda a collection of early Sanskrit hymns." "The most sophisticated ancient cosmological ideas came from Asia and particularly from India." "Here, there's a tradition of skeptical questioning and unselfconscious humility before the great cosmic mysteries." "Amidst the routine of daily life in, say, the harvesting and winnowing of grain people all over the world have wondered:" "Where did the universe come from?" "Asking this question is a hallmark of our species." "There's a natural tendency to understand the origin of the cosmos in familiar biological terms." "The mating of cosmic deities or the hatching of a cosmic egg or maybe the intonation of some magic phrase." "The big bang is our modern scientific creation myth." "It comes from the same human need to solve the cosmological riddle." "Most cultures imagined the world to be only a few hundred generations old." "Hardly anyone guessed that the cosmos might be far older." "But the ancient Hindus did." "They, like every other society noted and calibrated the cycles in nature." "The rising and setting of the sun and the stars the phases of the moon the passing of the seasons." "All over South India, an age-old ceremony takes place every January a rejoicing in the generosity of nature in the annual harvesting of the crops." "Every January, nature provides the rice to celebrate Pongal." "Even the draft animals are given the day off and garlanded with flowers." "(SPEAKING IN FOREIGN LANGUAGE)" "Colorful designs are painted on the ground to attract harmony and good fortune for the coming year." "Pongal, a simple porridge, a mixture of rice and sweet milk symbolizes the harvest, the return of the seasons." "(SHOUTING)" "However, this is not merely a harvest festival." "It has ties to an elegant and much deeper cosmological tradition." "The Pongal festival is a rejoicing in the fact that there are cycles in nature." "But how could such cycles come about unless the gods will them?" "And if there are cycles in the years of humans might there not be cycles in the eons of the gods?" "Hinduism is the only one of the world's great faiths dedicated to the idea that the cosmos itself undergoes an immense, indeed, an infinite number of deaths and rebirths." "It is the only religion in which the time scales correspond no doubt by accident, to those of modern scientific cosmology." "Its cycles run from our ordinary day and night to a day and night of Brahma 8.64 billion years long longer than the age of the Earth or the sun and about half the time since the big bang." "And there are much longer time scales still." "There is the deep and appealing notion that the universe is but the dream of the god who after 100 Brahma years dissolves himself into a dreamless sleep and the universe dissolves with him." "Until, after another Brahma century, he stirs recomposes himself and begins again to dream the great cosmic lotus dream." "Meanwhile, elsewhere there are an infinite number of other universes each with its own god dreaming the cosmic dream." "These great ideas are tempered by another perhaps still greater." "It is said that men may not be the dreams of the gods but rather that the gods are the dreams of men." "In India, there are many gods and each god has many manifestations." "These Chola bronzes cast in the 11th century include several different incarnations of the god Shiva seen here at his wedding." "The most elegant and sublime of these bronzes is a representation of the creation of the universe at the beginning of each cosmic cycle:" "A motif known as the cosmic dance of Shiva." "The god has four hands." "In the upper right hand is a drum whose sound is the sound of creation." "In the upper left hand is a tongue of flame a reminder that the universe, now newly created will, billions of years from now, be utterly destroyed." "Creation, destruction." "These profound and lovely ideas are central to ancient Hindu beliefs as exemplified in this Chola temple at Darasuram." "They're a kind of premonition of modern astronomical ideas." "Without doubt, the universe has been expanding since the big bang but it is, by no means, clear that it will continue to expand forever." "If there is less than a certain amount of matter in the universe then the mutual gravitation of the receding galaxies will be insufficient to stop the expansion and the universe will run away forever." "But if there is more matter than we can see hidden away in black holes, say or in hot but invisible gas between the galaxies then the universe holds together and partakes of a very Indian succession of cycles expansion followed by contraction cosmos upon cosmos, universes without end." "If we live in such an oscillating universe the big bang is not the creation of the cosmos but merely the end of the previous cycle the destruction of the last incarnation of the cosmos." "Neither of these modern cosmologies may be altogether to our liking." "In one cosmology, the universe is created somehow from nothing 15 to 20 billion years ago and expands forever the galaxies mutually receding until the last one disappears over our cosmic horizon." "Then the galactic astronomers are out of business the stars cool and die, matter itself decays and the universe becomes a thin, cold haze of elementary particles." "In the other, the oscillating universe the cosmos has no beginning and no end and we are in the midst of an infinite cycle of cosmic deaths and rebirths with no information trickling through the cusps of the oscillation." "Nothing of the galaxies, stars, planets life forms, civilizations evolved in the previous incarnation of the universe trickles through the cusp flitters past the big bang to be known in our universe." "The death of the universe in either cosmology may seem a little depressing." "But we may take some solace in the time scales involved." "These events will take tens of billions of years or more." "Human beings, or our descendants, whoever they might be can do a great deal of good in tens of billions of years before the cosmos dies." "If the universe truly oscillates if the modern scientific version of the old Hindu cosmology is valid then still stranger questions arise." "Some scientists think that when a red shift is followed by blue shift causality will be inverted and effects will precede causes." "First, the ripples spread out from a point on the water's surface." "Then I throw the stone into the pond." "Some scientists wonder, in an oscillating universe about what happens at the cusps at the transition from contraction to expansion." "Some think that the laws of nature are then randomly reshuffled that the physics and chemistry we have in this universe represent only one of an infinite range of possible natural laws." "It is easy to see that only a restricted range of laws of nature are consistent with galaxies and stars, planets life and intelligence." "If the laws of nature are randomly reshuffled at the cusps then it is only the most extraordinary coincidence that the cosmic slot machine has this time come up with a universe consistent with us." "Do we live in a universe which expands forever or in one where there is a nested set of infinite cycles?" "There's a way to find out the answer not by mysticism, but through science by making an accurate census of the total amount of matter in the universe or by seeing to the very edge of the cosmos." "Radio telescopes are able to detect distant quasars billions of light-years away expanding with the fabric of space." "By looking far out into space we are also looking far back into time back toward the horizon of the universe back toward the epoch of the big bang." "Radio telescopes have even detected the cosmic background radiation." "The fires of the big bang cooled and red-shifted faintly echoing down the corridors of time." "This is the very large array a collection of 17 separate radio telescopes all working collectively in a remote region of New Mexico." "Modern radio telescopes are exquisitely sensitive." "A distant quasar is so faint that its received radiation by some such telescope amounts to maybe a quadrillionth of a watt." "In fact, and this is a reasonably stunning piece of information the total amount of energy ever received by all the radio telescopes on the planet Earth is less than the energy of a single snowflake striking the ground." "In detecting the cosmic background radiation in counting quasars in searching for intelligent signals from space radio astronomers are dealing with amounts of energy which are barely there at all." "These radio telescopes, rising like giant flowers from the New Mexico desert are monuments to human ingenuity." "The faint radio waves are collected, focused assembled and amplified, and then converted into pictures of nebulae, galaxies and quasars." "If you had eyes that worked in radio light they'd probably be bigger than wagon wheels and this is the universe you'd see." "An elliptical galaxy, for example leaving behind it a long wake glowing in radio waves." "Radio waves reveal a universe of quasars interacting galaxies, titanic explosions." "Every time we use another kind of light to view the cosmos we open a new door of perception." "As the murmurs from the edge of the cosmos slowly accumulate our understanding grows." "This is an exploration of the ancient and the invisible a continuing human inquiry into the grand cosmological questions." "Another important recent finding was made by x-ray observatories in Earth orbit." "Artificial satellites launched to view the sky not in ordinary visible light, not in radio waves but in x-ray light." "There seems to be an immense cloud of extremely hot hydrogen glowing in x-rays between some galaxies." "Now, if this amount of intergalactic matter were typical of all clusters of galaxies then there may be just enough matter to close the cosmos and to trap us forever in an oscillating universe." "If the cosmos is closed there's a strange, haunting, evocative possibility one of the most exquisite conjectures in science or religion." "It's entirely undemonstrated it may never be proved, but it's stirring." "Our entire universe, to the farthest galaxy, we are told is no more than a closed electron in a far grander universe we can never see." "That universe is only an elementary particle in another still greater universe and so on forever." "Also, every electron in our universe, it is claimed is an entire miniature cosmos containing galaxies and stars and life and electrons." "Every one of those electrons contains a still smaller universe an infinite regression up and down." "Every human generation has asked about the origin and fate of the cosmos." "Ours is the first generation with a real chance of finding some of the answers." "One way or another we are poised at the edge of forever." "Except for planetary exploration, the study of galaxies and cosmology what this episode was about, have undergone the greatest advances since Cosmos was first broadcast." "For one thing, at last we have a good photograph of our own Milky Way galaxy about 100,000 light-years across." "Here it is." "It was taken by NASA's Coby satellite." "We see it edge on, of course, since we're embedded in the plane of the galaxy." "But you don't need a spacecraft to see it." "If it's a clear night, why not go out and take a look at the Milky Way?" "There's also new evidence suggesting that the Milky Way is not so much an ordinary spiral galaxy as a barred spiral, like this." "Important work has now been done on mapping how the galaxies are scattered through intergalactic space." "To the surprise of a lot of scientists on a scale of hundreds of millions of light-years the galaxies turn out not to be strewn at random or concentrated in clusters of galaxies but instead, strung out along odd, irregular surfaces, like this." "Every dot in this computer animation is a galaxy." "The computer lets us look at this distribution of galaxies from many points of view but this is how it looks from the Earth." "There is an odd mannequin shape that is presented by the distribution of galaxies." "This work has been done mainly by Margaret Geller with her collaborator John Huchra at Harvard University and the Smithsonian Institution." "It's a little like soap bubbles in a bathtub or dishwashing detergent." "The galaxies are on the surfaces of the bubbles." "The insides of the bubbles seem to have no galaxies in them at all." "An average bubble is about 100 million light-years across." "And that means that we've mapped still only a very small volume of the accessible universe the galaxies nearest to us." "But pretty soon, we should be able to extend this search out to enormous distances so far away in space, that we're looking back to the time that galaxies and their structures were first formed." "And this poses a real problem." "Most cosmologists hold that the galaxies arise from a preexisting lumpiness in the early universe with the little lumps growing into galaxies." "But the background radiation from the big bang that fills all of space has now been carefully measured by that same Coby satellite that took that picture." "Now, those radio waves seem almost perfectly uniform across the sky as if the big bang weren't lumpy or granular at all." "But if early radiation and matter in the universe weren't lumpy how could individual galaxies form?" "How could the bubbles form?" "Is there a contradiction between the uniformity of the big bang radio waves and the bubble structures formed by the galaxies?" "That's the question." "When our survey of galaxies reaches out to billions of light-years we'll have the answer to this question." "Incidentally, maybe you're thinking that the bubbles imply a bubble maker." "But then I'd have to ask you:" ""Who made the bubble maker?"" "There's another infinite regress lurking here." "And to one of the grandest questions whether there's enough matter in the universe to close it the only fair answer is that we don't know." "If it is closed what is the hidden matter that's closing it?" "Is it faint stars, black holes, massive neutrinos some exotic kind of dark matter unknown on Earth?" "We don't know." "But there are reasons to think that we'll soon find out the answers." "These three theories for quasars have now been abandoned." "Most astronomers now accept this theory for quasars." "Supermassive black holes almost certainly exist in the cores of many galaxies, including the Milky Way." "The redshift of distant galaxies is actually due to the stretching of light waves by the expansion of space." "At the time Cosmos was written, the Doppler Effect was the dominant metaphor used to teach redshift." "It is now widely thought that, although the results are similar to the Doppler Effect, redshift is not the same thing." "Recent observations of distant galaxies suggest that the expansion of the universe is accelerating and will therefore continue forever." "The current estimates are 1 2 to 1 5 billion years ago." "Very sensitive radio observations recently found a faint lumpiness in the cosmic background radiation." "This may be the embryonic large scale structure of the universe." "Recent observations of distant galaxies suggest that the expansion of the universe is accelerating." "If so, there cannot be enough matter to close the universe, and it will go on expanding forever." "SAGAN:" "The surface of the Earth is far more beautiful and far more intricate than any lifeless world." "Our planet is graced by life." "And one quality that sets life apart is its complexity slowly evolved through 4 billion years of natural selection." "You can describe in detail how a rock is put together in a single paragraph." "But to describe the basic structure of a tree or a blade of grass or even a one-celled animal you'd need many volumes." "It takes a great deal of information to make or even to characterize a living thing." "The measuring rod, the unit of information is something called the bit." "It's an answer, either yes or no to one unambiguously phrased question." "So to specify whether a light switch is on or off requires only a single bit." "To specify something of greater complexity requires more bits." "There's a popular game called 20 Questions which shows that a great deal can be specified in only 20 bits." "For example I have something in my hand." "What is it?" "Is it alive?" "Yes." "One bit." "Is it an animal?" "Nope." "Two bits." "Is it big enough to see?" "Yep." "Does it grow on the land?" "Yes." "Is it a cultivated plant?" "Nope." "Well, with only five bits we've made substantial progress to figuring out what it is." "With 20 skillfully chosen questions we could easily whittle all the cosmos down to a dandelion." "(BLOWS DANDELION)" "In our explorations of the cosmos the first step is to ask the right questions." "Then, not with 20 questions, but with billions we slowly distill from the complexity of the universe its underlying order." "This game has a serious purpose." "Its name is science." "Out here in the great cosmic dark there are countless stars and planets some far older than our solar system." "Though we cannot be certain, the same processes which led on Earth to the origin of life and intelligence should've been operating throughout the cosmos." "There may be a million worlds in the Milky Way galaxy alone which are at this moment inhabited by other intelligent beings." "What a wonder, what a joy it would be to know something about non-human intelligence." "And we can." "Here is an exotic inhabited world mostly covered with a liquid." "We seek the dominant intelligence that lives beneath its fluid surface." "This ocean of liquid water kilometers deep is teeming with strange forms of life." "There are communities of transparent beings." "There are societies of creatures which communicate by changing the patterns on their bodies." "There are beings that give off their own light." "There are hungry flowers that devour passersby gesticulating trees." "All manner of creatures that seem to violate the boundaries between plants and animals." "There are beings that flutter through the ocean like waltzing orchids." "These are a few of the species that inhabit the water world called Earth." "They're packed with information." "Each one has a rich behavioral repertoire to ensure its own survival." "But the grandest creatures on the planet the intelligent and graceful masters of the deep ocean are the great whales." "They are the largest animals ever to evolve on Earth larger, by far, than the dinosaurs." "Their ancestors were meat-eating mammals who migrated 70 million years ago in slow steps from the land into the waters." "Whales, like these humpbacks, are still mammals." "We humans have much in common with them." "Mothers suckle infants there's a long childhood when adults teach the young and there's a lot of play." "These are mammalian characteristics." "Vital if an animal is to learn." "But the sea is murky." "The senses of sight and smell which work well for mammals on the land are not much use here." "So the whales evolved an extraordinary ability to communicate by sound." "For tens of millions of years, the whales had no natural enemies." "And then, a new and alien and deadly creature suddenly appeared on the placid surface of the ocean." "(WHALES SINGING)" "These often noisy and occasionally deadly objects first appeared in large numbers only a few centuries ago." "They are artifacts manufactured by land creatures whose ancestors last lived in the oceans 350 million years ago." "(BELL RINGS)" "This particular one, however is on a mission of understanding." "It's called the Regina Maris the "Queen of the Sea."" "And one of its jobs is to record the sounds of the whales." "Some whale sounds are called songs but we really don't know what their contents are." "They range in frequency over a broadband of sounds down to frequencies well below the lowest sounds the human ear can make out." "A typical whale song lasts maybe 15 minutes." "The longest, perhaps half an hour." "Occasionally, a group of whales will leave their winter waters in the middle of a song and six months later they'll return and pick the song up at precisely the spot that they left it off." "Beat for beat." "Measure for measure." "Sound for sound." "Whales are very good at remembering." "Other times they will come back after an absence of six months, and the piece will have changed." "A different song will be on the whale hit parade." "Very often the members of the group will sing the same song together." "By some mutual consensus, some collaborative songwriting the piece changes slowly and often predictably." "I'm not very good at singing the songs of whales but here's a try." "In January a tiny fragment of a long whale song might sound like this." "Whoop." "Ahh." "In February, something like this." "Whoop." "Ahh." "Ahh." "And then in March, as maybe you'd predict..." "Whoop." "Ahh." "Ahh." "Ahh." "One additional "ahh" a month." "(WHALES SINGING)" "The complex patterns in the songs of the whales are sometimes repeated precisely." "If I imagine that the songs of the humpback whale are sung in a tonal language then the number of bits of information in one song is the same as the information content of the Iliad or the Odyssey." "(SPLASHING)" "Is it just a romantic notion that the whales and their cousins, the dolphins might have something akin to epic poetry?" "What might whales or dolphins have to talk or sing about?" "They have no manipulative organs." "They can't make great engineering constructs as we can." "But they're social creatures." "They hunt and swim, fish browse, frolic, mate, play run from predators." "There might be a lot to talk about." "The great danger for the whales is a newcomer an upstart animal only recently through technology become competent in the oceans:" "A creature called man." "For 99.99% of the history of whales there were no humans in the deep oceans." "During this period, the whales evolved their extraordinary communications system." "Some whales emit extremely loud sounds at a frequency of 20 hertz." "A hertz, which is spelled H-E-R-T-Z, is a unit of sound frequency and it represents one sound wave entering my ear every second." "A frequency of 2000 hertz sounds and looks like this." "(HIGH PITCHED TONE) 200 hertz, like this." "(MEDIUM PITCHED TONE)" "And 20 hertz, like this." "Although your TV set may not transmit sounds with frequencies as low as 20 hertz." "The American biologist Roger Payne has calculated that there's a deep sound channel in the ocean at these frequencies through which two whales could communicate anywhere in the world." "One whale might be off the Ross Ice Shelf then in Antarctica and communicate with another whale in the Aleutians in Alaska." "For most of their history, whales seem to have established a global communications network." "What two whales might have to say to each other separated by 15,000 kilometers, I haven't the foggiest idea." "But maybe it's a love song cast into the vastness of the deep." "Now, this calculation on the range of whale communications assumes that the oceans are quiet." "(WOOD CREAKS)" "(BELL RINGS)" "But in the 19th century, sailing ships like this one began to be replaced by steamships another invention of those strange land animals." "Commercial and military vessels became more abundant." "The noise pollution in the sea got much worse especially at a frequency of 20 hertz." "(ENGINE HUMS)" "The crew of this vessel try consciously to keep her quiet." "But when its engine is on it gets very loud at a frequency of 20 hertz." "Whales communicating across the oceans must've experienced greater and greater difficulties." "The distance over which they could communicate must have steadily decreased." "Two hundred years ago a typical distance that some whales could communicate across was perhaps 10,000 kilometers." "Today, on a typical day the corresponding number is perhaps a few 100 kilometers." "We have cut off the whales from themselves." "Creatures which were freely communicating for tens of millions of years have now effectively been silenced." "And we've done worse than that because there persists till this day a traffic in the dead bodies of whales." "There are humans who gratuitously hunt and slaughter whales and market the products for dog food or lipstick." "Many nations understand why whale murder is monstrous but the traffic continues chiefly by Japan and Norway and the Soviet Union." "We use "monster" to describe an animal somehow different from us, somehow scary." "But who's the more monstrous the whales, who ask to be left alone to sing their rich and plaintive songs or the humans, who set out to hunt them and destroy them and have brought many whale species close to the edge of extinction?" "We're interested in communication with extraterrestrial intelligence." "Wouldn't a good beginning be better communication with terrestrial intelligence with other human beings of different cultures and languages with the great apes, with the dolphins but particularly with the whales?" "To survive, a whale must know how to do things." "This knowledge is stored in two principal ways in the whale's genes and in their very large brains." "We can think of their genes and brains as something like libraries inside their bodies." "The information in the DNA, the genetic information includes how to nurse how to convert shrimp into blubber how to hold your breath on a dive one kilometer below the surface." "The information in the brains, the learned information involves such things as who's your mother or what the meaning is of that song we're hearing just now." "The gene library of whales and people and everybody else on Earth is made of DNA." "The only function of this complex molecule is to store and copy information." "We see here the set of instructions in human DNA written in a language billions of years older than any human tongue." "Each colored cluster of atoms is a letter in the genetic alphabet:" "The language of life." "There are billions of letters many billions of bits of information." "If you came from somewhere very different you wouldn't be able to specify a whale or a person in a game of 20 Questions with only 20 bits." "But a game called 10 Billion Questions might just work." "Every organism on Earth contains as its inheritance and legacy a portable library." "And the more bits of information you have, the more you can do." "The simplest organism, a virus needs only about 10,000 bits." "Equal to the amount of information on one page of an average book." "These are all the instructions it needs to infect some other organism and to reproduce itself which are the only things that viruses are any good at." "A bacterium uses roughly a million bits of information about 100 printed pages." "Bacteria have a lot more to do than viruses." "They're not thoroughgoing parasites." "Bacteria have to make a living." "What about a free-swimming one-celled amoeba?" "These creatures are also microscopic but in the realm of one-celled animals they are giants." "The whales of the microbial world." "Each contains about 400 million bits in its DNA the equivalent of about 80 volumes of 500 pages each." "That's how much information it takes to make an amoeba a creature like a small city wandering through a drop of water." "And what about a whale or a human being?" "Well, the answer seems to be that there's 5 billion bits." "Five billion bits of information in our encyclopedia of life in the nucleus of every one of our cells." "So if written out in, say, ordinary English those instructions, that information would fill 1000 volumes." "Think of it." "In every one of the 100 trillion cells in your body there's the contents of a complete library of instructions on how to make every part of you." "Those cells are smart." "If this were my gene library it would contain everything my body knows how to do without being taught." "The ancient information is written in exhaustive, careful, redundant detail." "How to laugh, how to sneeze, how to walk how to recognize patterns, how to reproduce how to digest an apple." "If written out in the language of chemistry what would the instructions for digesting the sugar in an apple look like?" "Well, let's see." "Amino acid synthesis, polypeptide chains transfer RNA, genetic code, enzyme expression enzyme phosphorylation." "We're getting warm." "Hexose monophosphate shunt, citric acid cycle..." "Here we are." "Anaerobic glycolysis." "Now, eating an apple may seem like a very simple thing but it's not." "In fact, if I consciously had to remember and direct all the chemical steps required to get energy out of food I'd probably starve to death." "And yet, even a bacterium can do anaerobic glycolysis." "That's why apples rot." "It's lunchtime for the bacteria." "They and we and all the creatures in between possess similar genetic instructions." "Our separate gene libraries have many pages in common which is another reminder of the deep interconnection of all living things on our planet because of a common evolutionary heritage." "Our present human technology can duplicate only a tiny fraction of the intricate biochemistry which our bodies seem to perform so effortlessly." "But we're just beginning the study of biochemistry." "Evolution has had billions of years of practice." "The DNA knows." "Now, what if what we had to do was so complicated that even several billion bits of information wasn't enough?" "What if, for example, the environment were changing so fast that the pre-coded genetic encyclopedia which may have served us perfectly well in the past is now not perfectly adequate?" "Why, then even a gene library of 1000 volumes wouldn't be enough." "That's why we have brains." "Like our other organs, the brain has evolved increasing over millions of years in complexity and information content." "Its structure reflects all the stages through which it has passed." "The brain has evolved from the inside out." "Deep inside is the oldest part, the so-called brain stem." "It conducts many of the basic biological functions including the rhythms of life like heartbeat and respiration." "The higher functions of the brain have evolved in three successive stages according to a provocative insight by the American biologist Paul MacLean." "You see, capping the brain stem is the so-called R-complex..." ""R" for reptile." "It's the seat of aggression, ritual, territoriality and social hierarchies." "It evolved some hundreds of millions of years ago in our reptilian ancestors." "So, deep inside our brains is something rather like the brain of a crocodile." "Surrounding the R-complex is the limbic system or mammal brain." "It evolved some tens of millions of years ago in ancestors who were mammals all right but not yet primates like monkeys or apes." "It's a major source of our moods and emotions our concern and care for the young." "And then, finally, on the outside of the brain living in a kind of uneasy truce with the more primitive brains beneath, is the cerebral cortex evolved millions of years ago in ancestors who were primates." "This is the point of embarkation for all our cosmic journeys." "The cerebral cortex where matter is transformed into consciousness." "Here, comprising more than two-thirds of the brain mass is the realm both of intuition and of critical analysis." "It's here that we have ideas and inspirations." "Here that we read and write." "Here that we do mathematics and music." "The cortex regulates our conscious lives." "It is the distinction of our species the seat of our humanity." "Art and science live here." "Civilization is a product of the cerebral cortex." "Behind the forehead are the frontal lobes of the cerebral cortex." "They may be where we anticipate events where we figure out the future." "But if we can foresee an unpleasant future we can take steps to avoid it." "Down here in the frontal lobes may be the means of ensuring human survival if we have the wisdom to pay attention." "Inside the cerebral cortex is the microscopic structure of thought." "The language of the brain is not the DNA language of the genes." "What we know is encoded in cells called neurons tiny switching elements every connection representing one bit of information." "How many neurons do each of us have?" "Maybe 100 billion." "Comparable to the number of stars in the Milky Way galaxy." "And there are something like 100 trillion neural connections." "This intricate and marvelous network of neurons has been called an enchanted loom where millions of flashing shuttles weave a dissolving pattern." "Even in sleep, the brain is pulsing and throbbing and flashing with the complex business of human life:" "Dreaming, remembering, figuring things out." "Our thoughts, our visions, our fantasies have a tangible, physical reality." "What does a thought look like?" "Well, it's made of hundreds of electrochemical impulses." "Over there, for example, is a spark of a memory." "Maybe the smell of lilacs on a country road in childhood." "And there goes a bit of an anxious all points bulletin." "Perhaps, "Where did I leave my keys? "" "The neurons store sounds too and snatches of music." "Whole orchestras play inside our heads." "The landscape of the human cerebral cortex is deeply furrowed." "There's a good reason for it." "These convolutions greatly increase the surface area available for information storage in a skull of limited size." "The world of thought is divided into two hemispheres." "Over there is the right hemisphere of the cerebral cortex." "It's mainly responsible for pattern recognition intuition, sensitivity, creative insights." "And over here is the left hemisphere presiding over rational, analytic and critical thinking." "These are the two sides the dual strengths, the essential opposites that characterize human thinking." "Before us are the means both for generating ideas and for testing their validity." "There's a continuous dialogue between the two hemispheres of the brain channeled through this immense bundle of nerve fibers which is called the corpus callosum." "It's a bridge between creativity and analysis both of which are necessary if we are to understand the world." "The information content of the human brain expressed in bits is comparable to the number of connections between the neurons in the cortex about 100 trillion bits 10 to the 14th connections." "If written out in English, it would fill 20 million volumes as many as in the world's largest libraries." "The equivalent of 20 million volumes worth of information is inside the heads of every one of us." "The brain is a very big place in a very small space." "Most of the books in the brain are up here in the cerebral cortex." "Down there, in the basement of the brain are the functions that our ancestors mainly depended on for survival:" "Aggression, child rearing, sex the willingness to follow leaders blindly." "Lots of things that we can still recognize in our lives today." "Of the higher brain functions some of them, like reading, writing, speaking seem to be located in particular places in the cerebral cortex." "On the other hand, each memory seems to be stored in many separate locales in the brain." "Old memories are in lots of places." "Here is one of my earliest memories." "(POURS LIQUID)" "MOTHER:" "That's a good boy." "Lunch is almost ready." "(CLICKS ON RADIO)" "(MUSIC PLAYS)" "That was a long time ago." "But its imprint has not faded in the library of this brain." "But the brain does much more than just recollect." "It inter-compares." "It synthesizes." "It analyzes." "It generates abstractions." "The simplest thought, like the concept of the number one has an elaborate, logical underpinning." "The brain has its own language for testing the world's structure and consistency." "But we never see the machinery of logical analysis only the conclusions." "There is so much more that we must figure out than the genes can know." "That's why the brain library has 10,000 times more information in it than the gene library." "Our passion for learning is the tool for our survival." "And unlike the musty bindings of our gene library in which hardly a word changes in a century the brain library is made of loose-leaf books." "We're constantly adding new pages and new volumes." "Emotions and ritual behavior patterns are built very deeply into us." "They're part of our humanity." "But they're not characteristically human." "Many other animals have feelings." "What distinguishes our species is thought." "The cerebral cortex is, in a way, a liberation." "We need no longer be trapped in the genetically inherited behavior patterns of lizards and baboons:" "Territoriality and aggression and dominance hierarchies." "We are, each of us largely responsible for what gets put into our brains for what, as adults, we wind up caring for and knowing about." "No longer at the mercy of the reptile brain we can change ourselves." "Think of the possibilities." "The city, like the brain has evolved in successive stages." "The vestiges of its past are still retained among the constructions of the present." "A city like New York developed from a small center and slowly grew leaving many of the old parts still functioning." "Some of the major streets date to the 17th century." "Its commercial hub, to the 18th century." "The water and gas works, to the 19th." "The electrical and communications systems, to the 20th century." "The city has evolved much faster than the brain." "Only 10,000 years ago the human brain looked exactly as it does today and we were just as smart." "But there were no cities only a few scattered encampments in the vast primordial forests." "Today, it's just the opposite." "Forests and grasslands often seem like scattered islands in a sea of cities." "If you were an observer from an alien world you would've noticed that something complicated has been happening over the last few thousand years." "It might take you a while to figure out the details but you would recognize by its complexity unmistakable evidence for intelligent life." "On closer scrutiny, you might recognize individual, intelligent beings." "The evolution of the city is due to their conscious activity." "Millions of human beings working, more or less, together to preserve the city, to reconstruct it and to change it." "It might be more efficient if all civic systems were periodically replaced from top to bottom." "But, as in the brain everything has to work during the renovation." "So the city mostly adds new parts while the old parts continue, more or less, to function." "For example, in the 17th century you traveled between Brooklyn and Manhattan across the East River by ferry." "In the 19th century, the technology became available to construct a suspension bridge across the river." "It was built precisely at the site of the ferry terminal because major thoroughfares were already converging there." "When it was possible to construct a tunnel under the river that, too, was built in the same place and for the same reason." "This use and restructuring of previous systems for new purposes is very much like the pattern of biological evolution." "Or consider Third Avenue." "In the 17th century you made your way uptown on foot or on horseback." "A little later, there were coaches the horses prancing, the coachmen cracking their whips." "And then these were replaced by horse-drawn trolleys clanging along fixed tracks on this avenue." "Then electrical technology developed and a great elevated railway line was constructed called the Third Avenue El, which dominated the street until 1954, when it was utterly demolished." "Anyway, the El was then replaced by buses and taxicabs which still are the main forms of public transportation on Third Avenue." "Now as gasoline becomes a rare commodity the combustion engine will be replaced by something else." "Maybe public transport on Third Avenue in the 21st century will be by, I don't know, pneumatic tubes or electric cars." "Every step in the evolution of Third Avenue transport has been conservative following a route first laid down in the 17th century." "But the brain is still more conservative than the city." "If this were the brain, we might have horse-drawn trolleys and the El and buses all operating simultaneously redundantly, competitively." "The vestiges of earlier history clearly in evidence." "When our genes could not store all the information necessary for our survival we slowly invented brains." "But then the time came, maybe tens of thousands of years ago when we needed to know more than could conveniently be stored in brains." "So we learned to stockpile enormous quantities of information outside our bodies." "We are the only species on Earth, so far as we know to have invented a communal memory." "The warehouse of that memory is called the library." "Libraries also have evolved." "The Assyrian library of Ashurbanipal had thousands of clay tablets." "The celebrated Library of Alexandria in Egypt consisted of almost a million papyrus scrolls." "Great modern libraries, like the New York Public Library contain some 10 million books." "That's more than 10 to the 14th bits of information in words." "More than 100 trillion bits, and if we count pictures it's something like 10 to the 15th bits of information." "Now, that's more than 10,000 times the total number of bits of information in our genes." "Something like 10 times the total amount of information in our brains." "If I were to read a book a week for my entire adult lifetime and I lived an ordinary lifetime when I was all done I would've read maybe a few thousand books." "No more." "In this library, that's from about here roughly to about here." "But that's only a 10th of a percent or so of the total number of books in the library." "The trick is to know which books to read." "But they're all here." "What an astonishing thing a book is." "It's a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles." "But one glance at it and you're inside the mind of another person." "Maybe somebody dead for thousands of years." "Across the millennia an author is speaking clearly and silently inside your head, directly to you." "Writing is perhaps the greatest of human inventions." "Binding together people who never knew each other." "Citizens of distant epochs." "Books break the shackles of time." "A book is proof that humans are capable of working magic." "And this room is filled with magic." "Some of the earliest authors wrote on bones and stones." "Cuneiform writing is the remote ancestor of the Western alphabet." "It was invented in the Near East about 5000 years ago." "Its purpose?" "To keep records." "Records of the purchase of grain, the sale of land the triumphs of kings, the statutes of priests the positions of the stars the prayers to the gods." "This cone was made around the year 2350 B.C." "4300 years ago, there were people chipping and chiseling away the message on this cone." "What is that message?" "It's a prayer." "The inscription on this cylinder honors a king." "Nebuchadnezzar, king of Babylon, in the 6th century B.C." "For thousands of years, writing was chiseled into stone scratched onto wax or bark or leather painted on bamboo or silk or paper but always in editions of one copy." "One copy at a time always, except for inscriptions on monuments for a tiny readership." "But then in China between the 2nd and the 6th centuries paper, ink and printing with carved wooden blocks were all invented, more or less, together permitting many copies of a work to be made and distributed." "This is Chinese magic from the 12th century." "It took 1000 years for the idea to catch on in relatively remote and backward Europe." "Just before the invention of movable type around the year 1450 there were only a few tens of thousands of books in Europe." "Every one of them handwritten." "Fifty years later, there were 10 million printed books in Europe." "Learning became available to anyone who could read." "Suddenly, books were being printed all over the world." "Magic was everywhere." "It is 23 centuries since the founding of the Alexandrian library." "Since then, 100 generations have lived and died." "If information were passed on merely by word of mouth how little we should know of our own past how slow would be our progress." "Everything would depend on what we'd been told on how accurate the account." "Ancient learning might be revered but in successive retellings, it would become muddled and then lost." "Books permit us to voyage through time to tap the wisdom of our ancestors." "A library connects us with the insights and knowledge of the greatest minds and the best teachers drawn from the whole planet and from all our history to instruct us without tiring and to inspire us to make our own contributions to the collective knowledge of the human species." "There's a fair number of Gutenberg Bibles and first folios of Shakespeare in the world but most of the books you see here are limited editions with very few surviving copies." "But there also exists in the world mass printings of paperbound books that I think are still more wonderful." "For the price of a modest meal you get the history of Rome." "Books are like seeds:" "They can lie dormant for centuries but they may also produce flowers in the most unpromising soil." "These books are the repositories of the knowledge of our species and of our long evolutionary journey from genes to brains to books." "Libraries in ancient Egypt bore these words on their walls:" ""Nourishment for the soul."" "And that's still a pretty fair assessment of what libraries provide." "Even at night, the city, like the brain is busy assimilating and distributing information." "Information keeps it alive and provides the tools to adapt to changing conditions." "The long human journey from genes to brains to books continues." "Information itself evolves nurtured by open communication and free inquiry." "The units of biological evolution are genes." "The units of cultural evolution are ideas." "Ideas are transported all over the planet." "They reproduce through communication." "They are selected by analysis and debate." "In the last few millennia, something extraordinary has happened on Earth." "Rich information from distant lands and peoples has become routinely available." "The number of bits to which we have access has grown dramatically." "Computers can now store and process enormous amounts of information extremely rapidly." "In our time, a revolution has begun." "A revolution perhaps as significant as the evolution of DNA and nervous systems and the invention of writing." "Direct communication among billions of human beings is now made possible by computers and satellites." "The potential for a global intelligence is emerging." "Linking all the brains on Earth into a planetary consciousness." "Elsewhere, there may be brains even planetary brains but there will be no brains quite like ours." "Mutation and natural selection are basically random processes." "If the Earth were started over again intelligence might very well emerge but anything closely resembling a human being would be unlikely." "On another planet with a different sequence of random processes to make heredity diversity and a different environment to select particular combinations of genes the chance of finding beings very similar to us must be close to zero." "But the chance of finding another form of intelligence isn't close to zero." "Their brains may well have evolved from the inside out as ours have." "They may well have switching elements analogous to our neurons but their neurons might be different." "Maybe they're superconductors which work at very low temperatures in which case, their speed of thought might be 10 million times faster than ours." "Or perhaps their neurons are not in direct physical contact with each other but in radio communication." "So a single intelligent being could be distributed among many different organisms." "There may be planets in which intelligent beings have not 10 to the 11th neurons each, as we do but 10 to the 20th or 10 to the 30th." "I wonder what they would know." "If we could make contact there would be much in their brains that would be of enormous interest to ours." "And vice versa." "I think extraterrestrial intelligence even beings astonishingly more evolved than we will be curious about us, about what we know, how we think the course of our evolution, the prospects for our future." "Within every human brain, patterns of electrochemical impulses are continuously forming and dissipating." "They reflect our emotions, ideas and memories." "When recorded and amplified these impulses sound like this." "(RUMBLING)" "But would an extraterrestrial being, no matter how advanced be able to read the mind that made these sounds?" "We ourselves are far from being able to do so." "But in fact, we have sent the very impulses you are hearing reflecting the emotions, ideas and memories of one human being on a voyage to the stars." "In August and September 1977 two Voyager spacecraft were launched on an epic journey to the outer solar system and beyond." "Their scientific mission was to explore the giant planets first Jupiter and its satellites and then Saturn and its system of moons." "Close encounters with these great worlds accelerate the Voyager spacecraft out of the solar system." "As an incidental consequence of their trajectories they will be carried inexorably into the realm of the stars where they will wander forever." "The ships will be slightly eroded within the solar system by micrometeorites, planetary rings systems and radiation belts." "But once past the planets they will endure for a billion years in the cold vacuum of interstellar space." "Perhaps in the distant future beings of an alien civilization will intercept these ships." "They'll examine our spacecraft and understand much about our science and technology." "But a machine alone can tell only so much about its makers." "So each bears a golden phonograph record with not only the brain waves of a woman from Earth but also an anthology of music, pictures and sounds of our planet including greetings in 60 human languages and the salutations of the humpback whales." "The record cover bears instructions on how to hear the sounds and see the pictures encoded on the disk." "Including some snapshots from the family album of a distant world." "The Voyager record is a message in a bottle cast into the cosmic ocean." "It contains some of our thoughts and our feelings something of the information we store in genes and brains and books." "The recipients, if any will understand the pictures and sounds incompletely at best." "But one thing would be clear about us:" "No one sends such a message on such a journey without a positive passion for the future." "For all the possible vagaries of the message they will be sure that we were a species endowed with hope and perseverance, at least a little intelligence and a longing to make contact with the cosmos." "Japan, Norway, Iceland and the Faeroe Islands are still slaughtering whales." "Russia is deciding whether to add itself again to this list." "This was written long before the Internet!" "SAGAN:" "In the vastness of the cosmos there must be other civilizations far older and more advanced than ours." "So shouldn't we have been visited?" "Shouldn't there be alien ships in the skies of Earth?" "There's nothing impossible in this idea." "And no one would be happier than me if we were visited." "But has it happened in fact?" "What counts is not what's plausible, not what we'd like to believe not what one or two witnesses claim." "But only what is supported by hard evidence rigorously and skeptically examined." "Extraordinary claims require extraordinary evidence." "Since 1947, there have been hundreds of thousands of reports of UFOs:" "Unidentified flying objects." "This subject has more to do with religion and superstition than with science." "Let's consider one of the most famous accounts of a supposed encounter with alien beings." "On September 19, 1961 an American couple was driving home through New Hampshire." "What's the matter, Delsey?" "SAGAN:" "They were returning along a lonely road, late at night from a vacation in Canada." "Remember, we have only their word for what happened next." "(TUNES RADIO)" "(STATIC FROM RADIO)" "I'm only getting static." "You still don't believe it, do you?" "No, I don't." "There must be a reasonable explanation." "Oh!" "SAGAN:" "They had observed, so they said a strange moving light in the sky." "By definition, an unidentified flying object." "It seemed to follow them for miles." "Easy there." "What's the matter with that dog?" "(HUMMING NOISE)" "What's that sound?" "I don't know." "After a time, the lighting patterns on the UFO changed." "It appeared to land." "What the..." "It blocked the road, preventing them from driving on." "They said they saw mouthless creatures approaching who were not exactly human." "Barney!" "Barney, what is that?" "At this point, the story becomes still stranger." "They lost all recollection of what happened in the next few hours." "But weeks later, they said they recalled some details and discussed the experience with others." "26 months later, under hypnosis they reported that a UFO had landed and that the crew had emerged." "They were captured, they said, and taken aboard the craft." "(WHINES)" "That was the story told by Betty and Barney Hill." "Virtually all scientists who've studied it are skeptical." "But UFO enthusiasts think the Hill case is a classic example of a "close encounter of the third kind."" "Why?" "What makes it so special?" "While on board, Betty had noticed a book written in an unknown hieroglyphic writing." "She was also shown a strange window through which she could see a glowing pattern of dots connected with lines." "It was, they told her, a star map displaying the routes of interstellar commerce." "Afterwards, they were released and permitted to return home." "Or at least, this is their story." "Believers find this compelling, or at least plausible chiefly because of the alleged star map." "Here's how Betty said it looked." "Why would we take this seriously?" "Because here is a real map widely publicized by UFO enthusiasts of 15 selected nearby stars, including the sun as seen from one particular vantage point in space." "This map includes stars that were first cataloged several years after Betty Hill recalled what she says she saw in the alien ship." "Her map required, we are told information that wasn't available on Earth." "There is a resemblance between the two maps, but that's because the lines corresponding to navigation routes have been copied from the Hill map onto the real star map." "If we were to substitute some other set of lines for the Hill lines, we find that the eye suddenly is biased against seeing any agreement between the two maps at all." "To make an objective test, however, let's remove the lines altogether." "And then there's very little resemblance left." "But these particular stars are selected from a large catalog of star positions." "Our vantage point is also selected to make the best possible fit with the Hill map." "If you can pick and choose from a large number of stars viewed from any vantage point in space you can always find a resemblance to the pattern you're looking for." "I'm surprised that nobody found a better fit to the Hill map." "The Hills' own psychiatrist described their story as a kind of dream." "There's no corroborating evidence." "The star map argument is worthless." "And yet this is one of the best attested cases of UFO close encounters." "For all I know, we're visited by a different extraterrestrial civilization every second Tuesday." "But there's no support for this appealing idea." "The extraordinary claims are not supported by extraordinary evidence." "There are curious daylight photos of UFOs." "Some look suspiciously like hats or hubcaps thrown into the air." "Photos can be faked." "More common are unidentified lights at night." "They're often aircraft." "But if we can't identify a light, that doesn't make it a spaceship." "Here's a movie of what you might think is a UFO." "Actually it's a piece of an asteroid burning up as it enters the Earth's atmosphere." "Most reports of UFOs turn out to be something else, like the refracted image of a planet or re-entry of an artificial satellite." "Some are psychological aberrations." "Some are hoaxes." "Never is there any compelling physical evidence a detailed close-up photograph of a strange spacecraft or a small device of extraterrestrial manufacture or a book written in alien hieroglyphics." "Never." "There are reports of such things, but never the things themselves." "The search for alien civilizations retains its importance despite the striking failure of the UFO evidence." "Most astronomers consider extraterrestrial life a subject worthy of vigorous, if cautious, pursuit." "For myself, I find something irresistible in the idea of discovering a token, maybe a simple inscription which would provide the key to understanding an alien civilization." "This is an appeal we humans have felt before." "In 1801 a famous physicist was governor of the French province of Isère." "His name was Joseph Fourier." "On an inspection of the schools in his province Fourier discovered an exceptional 1 1-year-old boy:" "Jean Francois Champollion." "The boy's precocious intellect and remarkable flair for languages had earned him the admiration of local scholars." "Fourier too was impressed." "What Champollion first saw in Fourier's house determined the course of his life and unlocked the secrets of an alien civilization." "Fourier had recently participated, as one of many scientists in Napoleon's expedition to the Middle East." "He had been in charge of cataloging the astronomical monuments of Egypt." "The boy was entranced by Fourier's collection of ancient Egyptian artifacts:" "The mysterious fragments of a lost world." "France at this time was flooded with such artifacts plundered by Napoleon and now arousing intense interest among scholars and the general public." "His attention was caught by a specimen of Egyptian hieroglyphics." ""What do they mean? " he asked." ""Nobody knows," was Fourier's reply." "Then and there, Champollion resolved he would understand this language no one could read he would decode the messages from another world and another time." "He became a superb linguist and immersed himself in the hieroglyphics." "Fourier edited the illustrated description of Napoleon's expedition." "The young Champollion studied it hungrily." "To the people of Europe these exotic images revealed an utterly alien civilization a world of towering monuments and magical names." "Dendera." "Karnak." "Luxor." "Every illustration was a riddle posed by the past to the present." "And among them were pictures of something called the Rosetta Stone and portraits of the people who lived among the ruins of the pharaohs." "Egypt became the land of Champollion's dreams." "But it was not until 1828 27 years after his fateful visit with Fourier that Champollion first set foot in Egypt." "With his companions, Champollion chartered boats in Cairo and sailed slowly upstream following the course of the Nile." "It was a journey of many weeks which Champollion recorded in extraordinary detail." "This was an expedition through time a voyage across the centuries to another world." "Champollion, as an adult had worked out a brilliant decipherment of the hieroglyphics." "A word, incidentally, that means "sacred carvings."" "Now Champollion was making a pilgrimage to the scene of ancient mysteries he had been the first to understand." "Champollion wrote:" ""The evening of the 16th, we finally arrived at Dendera." "We were only an hour away from the temples." "Could we resist the temptation?" "I ask the coldest of you mortals!" "To dine and leave immediately were the orders of the moment." "Alone and without guides, we crossed the fields." "Presuming that the temples were in a straight line from our boat we walked thus for an hour and a half without finding anything." "We discovered a man who put us on the correct route and ended up walking with us with good graces." "The temple appeared to us at last." "I shall not try to describe the impression which the porches and above all, the portico made on us." "We stayed there two hours in ecstasy running through the huge rooms and trying to read the exterior inscriptions in the moonlight."" "It was with no small rapture that Champollion entered the secret places of the temple and scanned the words that had waited patiently through half a million nights for a reader." "To his brother, Champollion wrote of his joy in confirming that he could understand the writing on these walls." ""I am now proud," he said..." ""...that having followed the course of the Nile I have the right to announce there is nothing to modify in our letter on the alphabet of hieroglyphics." "Our alphabet is good." "It is applicable with the same success, first of all in Egyptian monuments of the Roman epoch and, which is more interesting to the inscriptions on all temples, palaces and tombs of the Pharaonic epoch."" "Champollion was overwhelmed by the grandeur which surrounded him." ""It is the union," he said..." ""...of grace and majesty in the highest degree." "We in Europe are only dwafts." "No nation, ancient or modern, has conceived the art of architecture on such a sublime, great and imposing style as the ancient Egyptians." "They ordered everything to be done for people who are 100 feet high."" "This is the great temple of Karnak in upper Egypt continuously constructed over a period of more than 2,000 years until the time of Ptolemy." "It was here Champollion wrote:" ""That all the Pharaonic magnificence appeared to me."" "What he had seen elsewhere, he said "Seemed to me, miserable..." "On these walls and columns at Karnak at Dendera and everywhere else in Egypt Champollion found that he could read inscriptions that his decipherment of a few years earlier had been correct." "But how had he figured it out?" "Many had tried and failed to read the hieroglyphics." "A group of scholars thought they were a picture code full of metaphors mostly about eyeballs, wavy lines and animals." "Birds, especially birds, lots of birds." "Some deduced that the Egyptians had been colonists from China." "There were those who deduced it the other way around." "There's one who, from one look at the Rosetta Stone, deduced its meaning." "He said that the quickness of his decipherment enabled him "to avoid the systematic errors which invariably arise from prolonged reflection."" "You get better results, he's saying, if you don't think about it too much." "As in the search for extraterrestrial intelligence today the unbridled speculation by amateurs served to frighten many professionals right out of the field." "Champollion was not frightened." "He was also not distracted by the idea of hieroglyphs as pictorial metaphors." "Instead using the insights of a brilliant English physicist, Thomas Young he proceeded something like this:" "This is an exact replica of the Rosetta Stone." "The original had been found in the year 1 799 by a French soldier working on the fortifications of the Nile delta town of Rashid which the Europeans, in their persistence not to learn Arabic called "Rosetta."" "It had been part of an ancient temple which had been torn down." "If we look at it, we see that it clearly represents the same text in three different languages." "Up at the top, ancient Egyptian hieroglyphics." "In the middle, a kind of cursive and later hieroglyphic called "Demotic."" "And down at the bottom, the key to the enterprise:" "Greek." "Champollion could read ancient Greek, he was a superb linguist and discovered that this stone had been inscribed to commemorate the coronation of King Ptolemy V Epiphanes in the spring of the year 196 B.C." "As expected, the Greek text includes many references to King Ptolemy." "Here you can see it." ""Ptolemaeus."" "In roughly the same positions but in the hieroglyphic text are these ovals or "cartouches" as they are called." "And if this cartouche really means "Ptolemy" the individual hieroglyphs are not likely to be pictograms or metaphors." "Much more likely, they're letters or at least syllables." "Champollion had the presence of mind to count up the number of Greek words and the number of individual hieroglyphics in what are presumably equivalent texts." "He found that the number of individual hieroglyphs is much larger than the number of Greek words again implying that the hieroglyphs are mainly letters and syllables." "But which hieroglyphs correspond to which letters?" "Fortunately, Champollion had available a kind of second Rosetta Stone an obelisk which had been excavated at the temple of Philae and which had inscribed upon it cartouches representing the hieroglyphic equivalent of another Greek name:" "Cleopatra." "So here we have the Cleopatra cartouche." "And here, the Ptolemaeus cartouche." "Here, we've turned it around, changing left to right to right to left, and spread the hieroglyphs out so we see them all." "Now, immediately we notice that there are some similarities." "This first hieroglyph in Ptolemy is a kind of square." "The fifth hieroglyph in Cleopatra is a square." "But "Cleopatra"..." "Both of them seem to represent a "p."" "So Ptolemy and Cleopatra both give us the same interpretation:" "A square is a "p."" "Likewise, the fourth hieroglyph in Ptolemy is a lion." ""P-t-o-I."" "Likewise, the second hieroglyph in Cleopatra is an "I."" "So again it's consistent." "The pattern is emerging." "Likewise, this rope or hangman's noose "Ptolemy." It's an "o."" ""Cleopatra." It's an "o."" "And in this way, Champollion was able to assign letters for each of the hieroglyphs we see here." ""Ptolemaeus."" "And, likewise "Cleopatra."" "The eagle is an "a."" "Notice there are two different symbols for "t."" "But in English, the same sort of thing, "f" and "ph."" "Champollion discovered that the hieroglyphics were a simple substitution cipher." "Now, there's other stuff in here." "All the rest of this:" "What's that about?" "Well, he was later able to find out this is a symbol called the "ankh" which means "life."" "There's a "pt." That's an "ah." It makes "Ptah" name of a god." "And the whole cartouche read:" ""Ptolemy, ever living beloved of the god, Ptah."" "And the end of the "Cleopatra" is a short form meaning "Daughter of Isis."" "So it turns out that Champollion's opponents were not wholly wrong." "Some of the hieroglyphs, for example, the symbol "ankh" which means life, are ideograms or pictograms." "But the key to the enterprise Champollion's success, rested on his realization that the hieroglyphs were essentially letters and syllables." "In retrospect, it sounds almost easy." "But it took people hundreds of years before they figured it out." "Champollion walked these halls and casually read the inscriptions which had mystified everybody else." "Answering the question he had posed as a child to Fourier:" ""What do they mean? "" "What a joy it must have been for him to open this one-way communications channel with another civilization to permit a culture which had been mute for millennia to speak of its history, magic, medicine religion, politics, philosophy." "Today, we also are seeking messages from an ancient and exotic civilization." "A civilization hidden from us not in time, but in space." "Today, we are searching for a message from the stars." "We have not found it so far." "We have, as yet, no Champollion." "But we are just beginning." "Perhaps those who will decipher the first interstellar communications are alive at this moment, somewhere on the planet Earth." "Extraterrestrial beings will have a different biology a different culture, a different language." "How could we possibly understand their messages?" "Is there in any sense a cosmic Rosetta Stone?" "I believe there is." "All the technical civilizations in the cosmos, no matter how different must have one language in common:" "The language called "science."" "The laws of nature are everywhere the same." "Every chemical element has a specific signature in the spectrum." "So there are identical patterns in the light of a candle flame on Earth and in the light of a distant galaxy." "The spectra show not only that the same chemical elements exist throughout space but also that the same laws of quantum mechanics govern atoms everywhere." "Beings growing up on any world must come to grips with the identical laws of nature." "Galaxies billions of light-years distant evolve a spiral form." "So does our own Milky Way." "The same gravitational forces are at work." "And on planets also:" "There are spiral storm systems on Jupiter." "The same patterns are common on Earth." "The intelligent beings on every world will, sooner or later understand the laws of nature." "Someday, perhaps soon a message from the depths of space may arrive on our small world." "If we wish to understand it we first have to understand science." "We do not expect an advanced technical civilization on any other planet of our solar system." "If they were only a little behind us, 10,000 years, say they would have no advanced technology at all." "If they're a little ahead of us we who are already exploring the solar system then they should be here by now." "To communicate with other civilizations our technology must reach across not merely interplanetary distances but interstellar distances." "Ideally, the method should be inexpensive." "A huge amount of information could be sent and received at little cost." "It should be fast so an interstellar dialogue is eventually possible." "It ought to be obvious so that any technical civilization, no matter its evolutionary path will discover it early." "Surprisingly, there is such a method." "It's called radio astronomy." "This is the largest radio/radar telescope on the planet Earth, the Arecibo Observatory." "It's located in a remote valley on the island of Puerto Rico." "It sends and receives radio signals." "But it's so large and powerful it can communicate with an identical radio telescope 15,000 light-years away halfway to the center of the Milky Way galaxy." "The Arecibo Observatory has been used, although sparingly to search for signals from civilizations in space and, just once to broadcast a message to a distant star cluster called "M13."" "But is there anyone out there to talk to?" "With 400 billion stars in the Milky Way galaxy alone could ours be the only one with an inhabited planet?" "How much more likely it is that the galaxy is throbbing and humming with advanced societies." "Perhaps near one of those pinpoints of light in our night sky someone quite different from us is glancing idly at the star we call the sun and entertaining, just for a moment an outrageous speculation." "There are an enormous number of stars." "Only some of them will have planets suitable for life." "On only some of those worlds will intelligence arise." "And perhaps a few of those civilizations will avoid the trap jointly set by their technology and their passions." "If there are many civilizations, one of them should be rather close by." "If there are few civilizations then even the nearest may be very far away." "This is one of the great questions:" "How many advanced civilizations capable at least of radio astronomy are there in the Milky Way galaxy?" "Let's call the number of such civilizations by capital letter "N."" "It's a number." "It depends on many things." "It depends on the number of stars in the Milky Way." "Let's call that N sub-star." "The fraction of stars that have planets is called f sub-p." "The average number of planets in a given solar system ecologically suitable for life is called n sub-e." "The fraction of suitable planets in which life actually arises is called f sub-I." "The fraction of inhabited planets on which intelligence emerges is called f sub-i." "On the fraction of those planets in which the intelligent beings evolve a technical, communicative civilization call that f sub-c." "Finally, it depends on the fraction of a planet's lifetime that's graced by a technical civilization." "Call that f sub-L." "If we multiply all these numbers together we've estimated N, the number of civilizations." "This equation, due mainly to Frank Drake of Cornell is only a sentence." "The verb is "equals."" "So let's try to go through the program of this equation." "By carefully counting the number of stars in small but representative regions of the sky we find that the total number of stars in the Milky Way is about 400 billion." "That's a lot of stars." "What about planets?" "Well, in studies of double stars and investigations of the motions of nearby stars and in many theoretical studies we get a strong hint that many perhaps even most stars are accompanied by planets." "So let's take f sub-p the fraction of stars that have planets as a quarter." "Then, the total number of planetary systems in the galaxy is 400 billion times a quarter or 100 billion." "We'll write down our running totals in red." "Now if each system were to have, say ten planets as ours does, there would be 100 billion times ten or a trillion worlds in the galaxy." "A vast arena for the cosmic drama." "In our own solar system there are several bodies that might be suitable for life life of some sort." "There's the Earth, of course but there are possibilities for Mars, for Titan, perhaps for Jupiter." "If other systems are similar, there may be many suitable worlds per system." "But to be conservative, let's choose n sub-e equal two." "Two worlds suitable for life per system." "The planets that are suitable for life would be 100 billion times two, or 200 billion." "Now what about life?" "Under very general cosmic conditions the molecules of life are readily made and spontaneously self-assemble." "It's conceivable there might be some impediment, like some difficulty in the origin of the genetic code, say." "Although that's very unlikely, given billions of years for evolution." "On the Earth, life arose very fast after the planet was formed." "So let's choose f sub-I the fraction of suitable worlds in which life does arise, as a half." "The number of planets in the Milky Way in which life has arisen once is 100 billion times two, times a half." "Or again, 100 billion." "100 billion inhabited worlds." "Now the estimates get tougher." "Many individually unlikely events had to occur for our species and our technology to emerge." "On the other hand, there might be many different roads to high technology." "Some scientists think that the path from trilobites to radio telescopes, or the equivalent goes like a shot in all planetary systems." "Other scientists disagree." "Let's take some middle ground and choose f sub-i as a tenth and f sub-c as also a tenth." "Meaning that only one percent, a tenth times a tenth of inhabited planets eventually produce a technical civilization." "If we were to multiply all these factors together we would find 100 billion times a tenth times a tenth." "Or one billion planets on which civilizations have arisen at least once." "Now what percentage of the lifetime of a planet is marked by a technical civilization?" "Earth has harbored a civilization capable of radio astronomy only for a few decades, the last few out of a lifetime of a few billion years." "It's hardly out of the question that we might destroy ourselves tomorrow." "If that's a typical case, then f sub-L would be a few decades divided by a few billion years or one hundred millionth a very small number." "And then, N would be a billion times a hundred millionth." "Or N may be just ten civilizations." "A tiny smattering, a pitiful few technological civilizations in the galaxy." "But civilizations then might take billions of years of tortuous evolution to arise and then snuff themselves out in an instant of unforgivable neglect." "If this is a typical case there may be few others maybe nobody else at all for us to talk to." "But consider the alternative:" "That occasionally civilizations learn to live with high technology and survive for geological or stellar evolutionary time scales." "If only one percent of civilizations can survive technological adolescence then f sub-L would be not 100 millionth but only a hundredth." "And then the number of civilizations would be a billion times a hundredth." "The civilizations in the galaxy would be measured in the millions." "Millions of technical civilizations." "So if civilizations do not always destroy themselves shortly after discovering radio astronomy then the sky may be softly humming with messages from the stars with signals from civilizations enormously older and wiser than we." "If there are millions of civilizations in the Milky Way each capable of radio astronomy how far away is the nearest one?" "If they're distributed randomly through space then the nearest one will be some 200 light-years away." "But within 200 light-years there are hundreds of thousands of stars." "To find the needle in this haystack requires a dedicated and systematic search." "Many cosmic radio sources have nothing to do with intelligent life." "So how would we know that we were receiving a message?" "The transmitting civilization can make it very easy for us, if they wished." "Imagine we're in the course of a systematic search." "Or in the midst of some more conventional observations." "And suppose one day we find a strong signal slowly emerging." "Not just some background hiss but a methodical series of pulses." "(SIGNAL PINGS)" "The numbers one, two, three, five seven, eleven, thirteen." "A signal made of prime numbers." "Numbers divisible only by one and themselves." "There is no natural astrophysical process that generates prime numbers." "We would have to conclude that someone fond of elementary mathematics was saying hello." "(SIGNAL PINGS)" "This would be no more than a beacon to attract our attention." "The main message will be subtler more hidden, far richer." "We may have to work hard to find it." "But the beacon signal alone would be profoundly significant." "It would mean someone has learned to survive technological adolescence that self-destruction is not inevitable that we also may have a future." "Such knowledge, it seems to me might be worth a great price." "Very likely some new Champollion would go on to decode the main message, using our interstellar Rosetta Stone:" "The common language of science and mathematics." "Think of the glories of an exotic civilization far more advanced than we collected by the great radio telescopes of Earth." "Perhaps they'd send a compilation of the knowledge of a million worlds:" "The Encyclopedia Galactica." "Receiving an interstellar message would be a major event in human history and the beginning of the deprovincialization of our planet." "A serious and systematic radio search for extraterrestrial civilizations may come soon." "Preliminary steps are being taken both in the United States and in the Soviet Union." "It's comparatively inexpensive." "A search taking decades would cost less than the budget overruns on a single modest weapons system in a single year." "Our technology is now fully adequate for this great challenge." "But no systematic search program has ever been approved by any nation on Earth." "When will we decide to search for what other civilizations there may be in the vast cosmic ocean?" "But whether there are only a few advanced galactic civilizations or millions shouldn't some of them have voyaged to Earth?" "On one hand, if even a small fraction of technical civilizations learned to live with their potential for self-destruction there should be enormous numbers of them in the galaxy." "On the other hand, despite claims about UFOs and ancient astronauts there's no creditable evidence that Earth has been visited, now or ever." "But isn't this a contradiction?" "If the nearest civilization is, say, 200 light-years away it'd take them only 200 years to get from there to here at light speed." "Even if they were traveling 1000 times slower than that aliens could've come here during the tenure of human beings on Earth." "So why aren't they here?" "There's many possible answers." "One is that maybe we're the first." "Some technical civilization has to be first to emerge in the history of the galaxy." "Or maybe all technical civilizations promptly destroy themselves." "That seems to me very unlikely." "Maybe there's some problem with space flight that we've been too dumb to figure out." "Or maybe they are here, but in hiding because of an ethic of non-interference with emerging civilizations." "We might imagine them, curious and dispassionate watching us to determine whether this year again we manage to avoid self-destruction." "But there's another explanation which is consistent with what we know." "And that's that it's a big cosmos." "If years ago, an advanced interstellar spacefaring civilization emerged 200 light-years away, why would they come here?" "They'd have no reason to think the Earth was special." "There are no signs of technology, not even our radio transmissions which have had time to go 200 light-years." "From their point of view, all nearby planetary systems might seem equally attractive for exploration." "How would an interstellar civilization set out to explore its neighboring star systems?" "It might establish staging posts colonies, on planets of nearby stars." "But this would take time." "Time to find and modify favorable planets." "Time to build new spacecraft." "Eventually, later generations of explorers would set out wending their way among the worlds creating an interstellar nervous system binding up the stars." "Perhaps they'd come upon another expanding civilization and encounter beings previously known only from their radio transmissions." "Star wars are unlikely." "One civilization certainly would be far more advanced than the other." "It would be no contest." "Perhaps they would cooperate exploring together a small province of the Milky Way." "But even nearby civilizations could spend millions of years roving between the stars without ever stumbling upon our obscure solar system." "In a galaxy of 400 billion suns perhaps no one has found us just yet." "Advanced interstellar civilizations would know about many worlds." "Some inhabited, some barren." "Perhaps they would share their findings assembling some vast repository of the knowledge of countless worlds." "They might compile an Encyclopedia Galactica." "Suppose we could browse through that encyclopedia." "We would choose some nearby province of the galaxy a region that's fairly well-explored." "And then slowly leaf through the worlds." "The young Champollion was inspired by reading Fourier's description of Egypt." "Imagine the impact on us if we could study a rich compilation of not merely one world but billions." "Just possibly, not too far from our solar system we might find a technical civilization only a little more advanced than we." "Let's look them up in the Galactic Encyclopedia." "What would a civilization far more advanced than ours be up to?" "There may be engineering on a scale that dwafts our proudest achievements." "There may be cultures that disassemble other planets in their system and reassemble them around their world to make a ring or a shell with their planet inside." "Imagine the energy crisis of a really advanced planetary civilization." "They've used up all their fuels." "They depend on solar power." "But their growth is still severely limited by the energy available." "An enormous amount of energy is generated by the local star." "But most of the star's light doesn't fall on their planet." "So perhaps they would build a shell to surround their star and harvest every photon of sunlight." "Such beings, such civilizations would bear little resemblance to anything we know." "Perhaps someday there will be an entry in the Encyclopedia Galactica for our planet." "Or perhaps even now there exists somewhere a planetary dossier, garnered from our television broadcasts or from some discreet survey mission." "They may summon up the index of blue worlds in our part of the Milky Way until they came to the listing for Earth." "What would they know about us?" "What would they think of us?" "We have always watched the stars and mused about whether there are other beings who think and wonder." "In a cosmic setting vast and old beyond ordinary human understanding, we are a little lonely." "In the deepest sense, the search for extraterrestrial intelligence is a search for who we are." "Since Cosmos was released interest in UFOs has persisted." "It seems to me that there are fewer sightings of strange objects in the skies these days and more stories of encounters with alleged extraterrestrials like the account of Betty and Barney Hill that we dramatized." "There are still people who claim to have been abducted by aliens or even sexually abused, or even impregnated by them." "Best-selling purportedly serious books have been written about such claims." "But the critical fact remains that all we have still is just anecdote." "There are no close-up photos, no artifacts nothing that'd convince a skeptic." "All there are is stories." "And stories just aren't good enough on a matter of this importance." "I'm still waiting for hard evidence." "The radio search for extraterrestrial intelligence has been picking up." "In Harvard, Massachusetts, a radio telescope monitoring 8 million separate radio channels has been scanning the skies for signals." "This program, called META, is supported entirely by the Pasadena, California-based Planetary Society." "Paid for by members' contributions." "A similar planetary society search to examine the southern skies and the center of the Milky Way is to be performed in Argentina." "These searches are by far the most sophisticated ever attempted." "A much more sensitive program covering almost the entire accessible radio spectrum is to be mustered by NASA." "The search for extraterrestrial intelligence is central to our understanding of the universe and our view of ourselves." "It's well worth doing." "But the simple fact is that while we may consider extraterrestrial intelligence likely there is as yet no evidence at all that it exists." "The search continues." "NASA approved a long-term radio search for signals, but Congress cut off support in 1 994 after less than a year of actual observation." "This program was canceled by Congress." "The good news is that the search continues with public support at SETl@home." "You can take part using your personal computer at work or at home." "NARRATOR: "I call Heaven and Earth to witness against you this day that I have set before thee life and death the blessing and the curse." "Therefore choose life, that thou mayest live thou and thy seed."" "SAGAN:" "Nearly 200 years ago, in the Gulf of Alaska at a place called Lituya Bay two cultures that had never met experienced a first encounter." "The Tlingit people lived more or less as their ancestors had for thousands of years." "They were nomads moving often by canoe between numerous campsites where they caught plentiful fish and sea otters and traded with neighboring tribes." "(SPEAKS IN TLINGIT)" "The creator they worshiped was the raven god whom they pictured as an enormous black bird with white wings." "And one July day in 1786 the raven god appeared." "The Tlingit were terrified." "They knew that anyone looking directly at the god would be turned to stone." "From the other side of the planet had come an expedition led by the French explorer La Pérouse." "It was the most elaborately planned scientific voyage of the century sent around the world to gather knowledge about the geography natural history and peoples of distant lands." "But to the Tlingit whose world was confined to the islands and inlets of south Alaska this great vessel could have come only from the gods." "There was one among them who dared to look more deeply." "He was an old warrior, and nearly blind." "He said that his life was almost over." "For the common good, he would approach the raven to learn whether the god really would turn his people to stone." "He set out on his own voyage of discovery to confront the end of the world." "The old man made himself look hard at the raven and saw that it was not a great bird from the sky but the work of men like himself." "This first encounter turned out to be peaceful." "Men of the La Pérouse expedition were under orders to treat with respect any people they might discover." "An exceptional policy for its time, and after." "La Pérouse and the Tlingit exchanged goods and then the strange ship sailed away, never to return." "Not all encounters between nations had been so peaceful." "Before 1519 the Aztecs of Mexico had never seen a gun." "They too believed at first that their strange visitors had come from the sky." "The Spaniards under Cortez were not constrained by any injunctions against violence." "Their true nature and intentions soon became clear." "Unlike the La Pérouse expedition the Conquistadors sought, not knowledge, but gold." "They used their superior weapons to loot and murder." "In their madness, they obliterated a civilization." "In the name of piety in a mockery of their religion the Spaniards utterly destroyed a society with an art, astronomy, and architecture the equal of anything in Europe." "We revile the Conquistadors for their cruelty and shortsightedness for choosing death." "We admire La Pérouse and the Tlingit for their courage and wisdom for choosing life." "The choice is with us still." "But the civilization now in jeopardy is all humanity." "As the ancient mythmakers knew we're children equally of the Earth and sky." "In our tenure on this planet we've accumulated dangerous evolutionary baggage:" "Propensities for aggression and ritual submission to leaders, hostility to outsiders." "All of which puts our survival in some doubt." "But we've also acquired compassion for others love for our children a desire to learn from history and experience and a great, soaring, passionate intelligence." "The clear tools for our continued survival and prosperity." "Which aspects of our nature will prevail is uncertain." "Particularly when our visions and prospects are bound to one small part of the small planet Earth." "But up there in the cosmos an inescapable perspective awaits." "National boundaries are not evident when we view the Earth from space." "Fanatic ethnic or religious or national identifications are difficult to support when we see our planet as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and citadel of the stars." "There are not yet obvious signs of extraterrestrial intelligence and this makes us wonder whether civilizations like ours rush inevitably, headlong to self-destruction." "I dream about it." "And sometimes they're bad dreams." "In the vision of a dream I once imagined myself searching for other civilizations in the cosmos." "Among a hundred billion galaxies and a billion trillion stars life and intelligence should have arisen on many worlds." "Some worlds are barren and desolate on them life never began or may have been extinguished in some cosmic catastrophe." "There may be worlds rich in life but not yet evolved to intelligence and high technology." "There may be civilizations that achieve technology and then promptly use it to destroy themselves." "And perhaps there are also beings who learned to live with their technology and themselves." "Beings who endure and become citizens of the cosmos." "Immersed in these thoughts I found myself approaching a world that was clearly inhabited a world I had visited before." "I saw a planet encompassed by light and recognized the signature of intelligence." "But suddenly darkness, total and absolute." "In my dream I could read the Book of Worlds." "A vast encyclopedia of a billion planets within the Milky Way." "What could the computer tell me about this now-darkened world?" "They must have survived some earlier catastrophe." "Locally initiated contact:" "Maybe their television broadcasts." "Their biology was different from ours." "High technology." "I wondered what those lights had been for." "There must have been signs of trouble." "Probability of survival in a century less than 1%." "Not very good odds." ""Communications interrupted."" "Their world society had failed." "They had made the ultimate mistake." "I felt a longing to return to Earth." "The television transmissions of Earth rushed past me expanding away from our planet at the speed of light." "(RANDOM TELEVISION AUDIO PLAYS)" "ANNOUNCER 1:" "The nuclear test-ban treaty was signed today." "ANNOUNCER 2:" "Something's happened in the motorcade." "Stand by." "ANNOUNCER 3:" "For 64,000 dollars..." "ANNOUNCER 4:... bombing of Hanoi was designed to cripple morale..." "NIXON:" "There can be no whitewash at the White House." "ANNOUNCER 5:... series of record oil company profits were revealed..." "ANNOUNCER 6:... if the serious course of events continued." "Foreign ministers are at this moment..." "Please stand by." "Stand by." "SAGAN:" "Then, suddenly silence total and absolute." "But the dream was not yet done." "Had we destroyed our home?" "What had we done to the Earth?" "There had been many ways for life to perish at our hands." "We had poisoned the air and water." "We had ravaged the land." "Perhaps we had changed the climate." "Could it have been a plague or nuclear war?" "I remembered the galactic computer." "What would it say about the Earth?" "There was our region of the galaxy." "There was our world." "I had found the entry for Earth." "Humanity, third from the sun." "They had heard our television broadcasts and thought them an application for cosmic citizenship." "Our technology had been growing enormously." "They got that right." "200 nation states." "About six global powers." "The potential to become one planet." "Probability of survival over a century, here also less than I% ." "So it was nuclear war." "A full nuclear exchange." "There would be no more big questions." "No more answers." "Never again a love or a child." "No descendants to remember us and be proud." "No more voyages to the stars." "No more songs from the Earth." "I saw East Africa and thought a few million years ago we humans took our first steps there." "Our brains grew and changed." "The old parts began to be guided by the new parts." "And this made us human with compassion and foresight and reason." "But instead, we listened to that reptilian voice within us counseling fear, territoriality aggression." "We accepted the products of science." "We rejected its methods." "Maybe the reptiles will evolve intelligence once more." "Perhaps, one day, there will be civilizations again on Earth." "There will be life." "There will be intelligence." "But there will be no more humans." "Not here, not on a billion worlds." "Every thinking person fears nuclear war and every technological nation plans for it." "Everyone knows it's madness and every country has an excuse." "There's a dreary chain of causality." "The Germans were working on the bomb at the beginning of World War II." "So the Americans had to make one first." "If the Americans had one, the Russians had to have one." "Then, the British, the French the Chinese, the Indians, the Pakistanis." "Many nations now collect nuclear weapons." "They're easy to make." "You can steal fissionable material from nuclear reactors." "Nuclear weapons have almost become a home handicraft industry." "The conventional bombs of World War II were called "blockbusters."" "Filled with 20 tons of TNT, they could destroy a city block." "All the bombs dropped on all the cities of World War II amounted to some 2 million tons of TNT." "Two megatons." "Coventry and Rotterdam." "Dresden and Tokyo." "All the death that rained from the skies between 1939 and 1945." "100,000 blockbusters." "Two megatons." "Today, two megatons is the equivalent of a single thermonuclear bomb." "One bomb with the destructive force of the Second World War." "But there are tens of thousands of nuclear weapons." "The missile and bomber forces of the Soviet Union and U. S have warheads aimed at over 15,000 designated targets." "No place on the planet is safe." "The energy contained in these weapons genies of death patiently awaiting the rubbing of the lamps totals far more than 10,000 megatons." "But with the destruction concentrated efficiently not over six years, but over a few hours." "A blockbuster for every family on the planet." "A World War II every second for the length of a lazy afternoon." "(BIRDS CHIRPING)" "The bomb dropped on Hiroshima killed 70,000 people." "In a full nuclear exchange in the paroxysm of global death the equivalent of a million Hiroshima bombs would be dropped all over the world." "In such an exchange not everyone would be killed by the blast and firestorm and the immediate radiation." "There would be other agonies:" "Loss of loved ones the legions of the burned and blinded and mutilated the absence of medical care disease, plague long-lived radiation poisoning of the soil and the water." "The threat of tumors and stillbirths and malformed children." "And the hopeless sense of a civilization destroyed for nothing." "The knowledge that we could have prevented it and did not." "The global balance of terror pioneered by the U.S. and the Soviet Union holds hostage all the citizens of the Earth." "Each side persistently probes the limits of the other's tolerance like the Cuban missile crisis the testing of anti-satellite weapons the Vietnam and Afghanistan wars." "The hostile military establishments are locked in some ghastly mutual embrace." "Each needs the other." "But the balance of terror is a delicate balance with very little margin for miscalculation." "And the world impoverishes itself by spending a trillion dollars a year on preparations for war." "And by employing perhaps half the scientists and high technologists on the planet in military endeavors." "How would we explain all this to a dispassionate extraterrestrial observer?" "What account would we give of our stewardship of the planet Earth?" "We have heard the rationales offered by the superpowers." "We know who speaks for the nations." "But who speaks for the human species?" "Who speaks for Earth?" "From an extraterrestrial perspective, our global civilization is clearly on the edge of failure in the most important task it faces:" "Preserving the lives and well-being of its citizens and the future habitability of the planet." "But if we're willing to live with the growing likelihood of nuclear war shouldn't we also be willing to explore vigorously every possible means to prevent nuclear war?" "Shouldn't we consider, in every nation major changes in the traditional ways of doing things?" "A fundamental restructuring of economic, political, social and religious institutions?" "We've reached a point where there can be no more special interests or cases." "Nuclear arms threaten every person on Earth." "Fundamental changes in society are sometimes labeled impractical or contrary to human nature as if nuclear war were practical or as if there were only one human nature." "But fundamental changes can clearly be made." "We're surrounded by them." "In the last two centuries, abject slavery which was with us for thousands of years has almost entirely been eliminated in a stirring worldwide revolution." "Women, systematically mistreated for millennia are gradually gaining the political and economic power traditionally denied to them." "And some wars of aggression have recently been stopped or curtailed because of a revulsion felt by the people in the aggressor nations." "The old appeals to racial, sexual, and religious chauvinism and to rabid nationalist fervor are beginning not to work." "A new consciousness is developing which sees the Earth as a single organism and recognizes that an organism at war with itself is doomed." "We are one planet." "One of the great revelations of the age of space exploration is the image of the Earth, finite and lonely somehow vulnerable, bearing the entire human species through the oceans of space and time." "But this is an ancient perception." "In the 3rd century B. C our planet was mapped and accurately measured by a Greek scientist named Eratosthenes, who worked in Egypt." "This was the world as he knew it." "Eratosthenes was the director of the great Library of Alexandria the center of science and learning in the ancient world." "Aristotle had argued that humanity was divided into Greeks and everybody else, who he called "barbarians" and that the Greeks should keep themselves racially pure." "He taught that it was fitting for the Greeks to enslave other peoples." "But Eratosthenes criticized Aristotle for his blind chauvinism." "He believed there was good and bad in every nation." "The Greek conquerors had invented a new god for the Egyptians but he looked remarkably Greek." "Alexander was portrayed as pharaoh in a gesture to the Egyptians." "But in practice, the Greeks were confident of their superiority." "The protests of the librarian hardly constituted a serious challenge to prevailing prejudices." "Their world was as imperfect as our own." "But the Ptolemies, the Greek kings of Egypt who followed Alexander had at least this virtue:" "They supported the advancement of knowledge." "Popular ideas about the nature of the cosmos were challenged and some of them, discarded." "New ideas were proposed and found to be in better accord with the facts." "There were imaginative proposals, vigorous debates brilliant syntheses." "The resulting treasure of knowledge was recorded and preserved for centuries on these shelves." "Science came of age in this library." "The Ptolemies didn't merely collect old knowledge." "They supported scientific research and generated new knowledge." "The results were amazing." "Eratosthenes accurately calculated the size of the Earth." "He mapped it and he argued that it could be circumnavigated." "Hipparchus anticipated that stars come into being slowly move during the course of centuries and eventually perish." "It was he who first catalogued the positions and magnitudes of the stars in order to determine whether there were such changes." "Euclid produced a textbook on geometry which human beings learned from for 23 centuries." "It's still a great read, full of the most elegant proofs." "Galen wrote basic works on healing and anatomy which dominated medicine until the Renaissance." "These are just a few examples." "There were dozens of great scholars here and hundreds of fundamental discoveries." "Some of those discoveries have a distinctly modern ring." "Apollonius of Perga studied the parabola and the ellipse curves that we know today describe the paths of falling objects in a gravitational field and space vehicles traveling between the planets." "Heron of Alexandria invented steam engines and gear trains he was the author of the first book on robots." "Imagine how different our world would be if those discoveries had been used for the benefit of everyone." "If the humane perspective of Eratosthenes had been widely adopted and applied." "But this was not to be." "Alexandria was the greatest city the Western world had ever seen." "People from all nations came here to live, to trade, to learn." "On a given day these harbors were thronged with merchants and scholars, tourists." "It's probably here that the word "cosmopolitan" realized its true meaning of a citizen, not just of a nation but of the cosmos." "To be a citizen of the cosmos." "Here were clearly the seeds of our modern world." "But why didn't they take root and flourish?" "Why, instead, did the West slumber through 1000 years of darkness until Columbus and Copernicus and their contemporaries rediscovered the work done here?" "I cannot give you a simple answer but I do know this:" "There is no record in the entire history of the library that any of the illustrious scholars and scientists who worked here ever seriously challenged a single political or economic or religious assumption of the society in which they lived." "The permanence of the stars was questioned." "The justice of slavery was not." "Science and learning in general were the preserve of the privileged few." "The vast population of this city had not the vaguest notion of the great discoveries being made within these walls." "How could they?" "The new findings were not explained or popularized." "The progress made here benefited them little." "Science was not part of their lives." "The discoveries in mechanics, say or steam technology mainly were applied to the perfection of weapons to the encouragement of superstition to the amusement of kings." "Scientists never seemed to grasp the enormous potential of machines to free people from arduous and repetitive labor." "The intellectual achievements of antiquity had few practical applications." "Science never captured the imagination of the multitude." "There was no counterbalance to stagnation, to pessimism to the most abject surrender to mysticism." "So when, at long last the mob came to burn the place down there was nobody to stop them." "Let me tell you about the end." "It's a story about the last scientist to work in this place." "A mathematician, astronomer, physicist and head of the school of Neo- Platonic philosophy in Alexandria." "That's an extraordinary range of accomplishments for any individual, in any age." "Her name was Hypatia." "She was born in this city in the year 370 A.D." "This was a time when women had essentially no options." "They were considered property." "Nevertheless, Hypatia was able to move freely unselfconsciously through traditional male domains." "By all accounts, she was a great beauty." "And although she had many suitors she had no interest in marriage." "The Alexandria of Hypatia's time, by then long under Roman rule was a city in grave conflict." "Slavery, the cancer of the ancient world had sapped classical civilization of its vitality." "The growing Christian Church was consolidating its power and attempting to eradicate pagan influence and culture." "Hypatia stood at the focus at the epicenter of mighty social forces." "Cyril, the Bishop of Alexandria, despised her in part because of her close friendship with a Roman governor but also because she was a symbol of learning and science which were largely identified by the early Church with paganism." "In great personal danger Hypatia continued to teach and to publish until, in the year 415 A.D., on her way to work she was set upon by a fanatical mob of Cyril's followers." "They dragged her from her chariot tore off her clothes and flayed her flesh from her bones with abalone shells." "Her remains were burned, her works obliterated her name forgotten." "Cyril was made a saint." "The glory you see around me is nothing but a memory." "It does not exist." "The last remains of the library were destroyed within a year of Hypatia's death." "It's as if an entire civilization had undergone a sort of self-inflicted radical brain surgery so that most of its memories discoveries, ideas and passions were irrevocably wiped out." "The loss was incalculable." "In some cases, we know only the tantalizing titles of books that had been destroyed." "In most cases, we know neither the titles nor the authors." "We do know that in this library there were 123 different plays by Sophocles of which only seven have survived to our time." "One of those seven is Oedipus Rex." "Similar numbers apply to the lost works of Aeschylus, Euripides, Aristophanes." "It's a little as if the only surviving works of a man named William Shakespeare were Coriolanus and A Winter's Tale although we knew he had written some other things which were highly prized in his time." "Plays called Hamlet, Macbeth A Midsummer's Night Dream, Julius Caesar, King Lear Romeo and Juliet." "History is full of people who, out of fear or ignorance or the lust for power have destroyed treasures of immeasurable value which truly belong to all of us." "We must not let it happen again." "We have considered the destruction of worlds and the end of civilizations." "But there is another perspective by which to measure human endeavors." "Let me tell you a story about the beginning." "Some 15 billion years ago our universe began with the mightiest explosion of all time." "The universe expanded, cooled and darkened." "Energy condensed into matter, mostly hydrogen atoms." "And these atoms accumulated into vast clouds rushing away from each other that would one day become the galaxies." "Within these galaxies the first generation of stars was born kindling the energy hidden in matter flooding the cosmos with light." "Hydrogen atoms had made suns and starlight." "There were in those times no planets to receive the light and no living creatures to admire the radiance of the heavens." "But deep in the stellar furnaces nuclear fusion was creating the heavier atoms:" "Carbon and oxygen, silicon and iron." "These elements, the ash left by hydrogen were the raw materials from which planets and life would later arise." "At first, the heavy elements were trapped in the hearts of the stars." "But massive stars soon exhausted their fuel and in their death throes returned most of their substance back into space." "The interstellar gas became enriched in heavy elements." "In the Milky Way galaxy the matter of the cosmos was recycled into new generations of stars now rich in heavy atoms." "A legacy from their stellar ancestors." "And in the cold of interstellar space great turbulent clouds were gathered by gravity and stirred by starlight." "In their depths the heavy atoms condensed into grains of rocky dust and ice and complex carbon-based molecules." "In accordance with the laws of physics and chemistry hydrogen atoms had brought forth the stuff of life." "In other clouds, more massive aggregates of gas and dust formed later generations of stars." "As new stars were formed tiny condensations of matter accreted near them inconspicuous motes of rock and metal, ice and gas that would become the planets." "And on these worlds, as in interstellar clouds organic molecules formed made of atoms that had been cooked inside the stars." "In the tide pools and oceans of many worlds molecules were destroyed by sunlight and assembled by chemistry." "One day, among these natural experiments a molecule arose, that, quite by accident was able to make crude copies of itself." "As time passed, self-replication became more accurate." "Those molecules that copied better produced more copies." "Natural selection was underway." "Elaborate molecular machines had evolved." "Slowly, imperceptibly, life had begun." "Collectives of organic molecules evolved into one-celled organisms." "These produced multi-celled colonies." "Their various parts became specialized organs." "Some colonies attached themselves to the sea floor others swam freely." "Eyes evolved, and now the cosmos could see." "Living things moved on to colonize the land." "The reptiles held sway for a time but gave way to small warm-blooded creatures with bigger brains who developed dexterity and curiosity about their environment." "They learned to use tools and fire and language." "Star stuff, the ash of stellar alchemy had emerged into consciousness." "We are a way for the cosmos to know itself." "We are creatures of the cosmos and have always hungered to know our origins to understand our connection with the universe." "How did everything come to be?" "Every culture on the planet has devised its own response to the riddle posed by the universe." "Every culture celebrates the cycles of life and nature." "There are many different ways of being human." "But an extraterrestrial visitor examining the differences among human societies would find those differences trivial..." "We are one species." "We are star stuff, harvesting starlight." "Our lives, our past and our future are tied to the sun, the moon and the stars." "Our ancestors knew that their survival depended on understanding the heavens." "They built observatories and computers to predict the changing of the seasons by the motions in the skies." "We are, all of us descended from astronomers." "The discovery of order in the universe of the laws of nature is the foundation on which science builds today." "Our conception of the cosmos all of modern science and technology trace back to questions raised by the stars." "Yet, even 400 years ago we still had no idea of our place in the universe." "The long journey to that understanding required both an unflinching respect for the facts and a delight in the natural world." "Johannes Kepler wrote:" ""We do not ask for what useful purpose the birds do sing for song is their pleasure since they were created for singing." "Similarly we ought not to ask why the human mind troubles to fathom the secrets of the heavens." "The diversity of the phenomena of nature is so great and the treasures hidden in the heavens so rich precisely in order that the human mind shall never be lacking in fresh nourishment."" "It is the birthright of every child to encounter the cosmos anew in every culture and every age." "When this happens to us, we experience a deep sense of wonder." "The most fortunate among us are guided by teachers who channel this exhilaration." "We are born to delight in the world." "We are taught to distinguish our preconceptions from the truth." "Then, new worlds are discovered as we decipher the mysteries of the cosmos." "Science is a collective enterprise that embraces many cultures and spans the generations." "In every age, and sometimes in the most unlikely places there are those who wish with a great passion to understand the world." "We don't know where the next discovery will come from." "What dream of the mind's eye will remake the world." "These dreams begin as impossibilities." "Once, even to see a planet through a telescope was an astonishment." "But we studied these worlds we figured out how they moved in their orbits and soon we were planning voyages of discovery beyond the Earth and sending robot explorers to the planets and the stars." "We humans long to be connected with our origins so we create rituals." "Science is another way to express this longing." "It also connects us with our origins." "And it, too, has its rituals and its commandments." "Its only sacred truth is that there are no sacred truths." "Temperature systems..." "SAGAN:" "All assumptions must be critically examined." "Arguments from authority are worthless." "FEMALE SCIENTIST:" "Transducer power is on." "SAGAN:" "Whatever is inconsistent with the facts no matter how fond of it we are must be discarded or revised." "Science is not perfect." "It's often misused." "It's only a tool." "But it's the best tool we have self-correcting, ever-changing applicable to everything." "With this tool, we vanquish the impossible." "With the methods of science we have begun to explore the cosmos." "For the first time, scientific discoveries are widely accessible." "Our machines the products of science are now beyond the orbit of Saturn." "A preliminary spacecraft reconnaissance has been made of 20 new worlds." "We have learned to value careful observations to respect the facts, even when they are disquieting when they seem to contradict conventional wisdom." "The Canterbury monks faithfully recorded an impact on the moon and the Anasazi people, an explosion of a distant star." "They saw for us as we see for them." "We see further than they only because we stand on their shoulders." "We build on what they knew." "We depend on free inquiry and free access to knowledge." "We humans have seen the atoms which constitute all of matter and the forces that sculpt this world and others." "We know the molecules of life are easily formed under conditions common throughout the cosmos." "We have mapped the molecular machines at the heart of life." "We have discovered a microcosm in a drop of water." "We have peered into the bloodstream and down on our stormy planet to see the Earth as a single organism." "We have found volcanoes on other worlds and explosions on the sun studied comets from the depths of space and traced their origins and destinies listened to pulsars and searched for other civilizations." "We humans have set foot on another world in a place called the Sea of Tranquility an astonishing achievement for creatures such as we whose earliest footsteps, 3 ½ million years old are preserved in the volcanic ash of East Africa." "We have walked far." "These are some of the things that hydrogen atoms do given 15 billion years of cosmic evolution." "It has the sound of epic myth." "But it's simply a description of the evolution of the cosmos as revealed by science in our time." "And we we who embody the local eyes and ears and thoughts and feelings of the cosmos we've begun, at last, to wonder about our origins." "Star stuff, contemplating the stars organized collections of 10 billion- billion-billion atoms contemplating the evolution of matter tracing that long path by which it arrived at consciousness here on the planet Earth and perhaps, throughout the cosmos." "Our loyalties are to the species and the planet." "We speak for Earth." "Our obligation to survive and flourish is owed not just to ourselves but also to that cosmos, ancient and vast from which we spring." "The greatest thrill for me in reliving this adventure has been not just that we've completed the preliminary reconnaissance with spacecraft of the entire solar system." "And not just that we've discovered astonishing structures in the realm of the galaxies but especially that some of Cosmos' boldest dreams about this world are coming closer to reality." "Since this series' maiden voyage the impossible has come to pass." "Mighty walls that maintained insuperable ideological differences have come tumbling down." "Deadly enemies have embraced and begun to work together." "The imperative to cherish the Earth and to protect the global environment that sustains all of us has become widely accepted." "And we've begun, finally the process of reducing the obscene number of weapons of mass destruction." "Perhaps we have, after all decided to choose life." "But we still have light-years to go to ensure that choice even after the summits and the ceremonies and the treaties." "There are still some 50,000 nuclear weapons in the world." "And it would require the detonation of only a tiny fraction of them to produce a nuclear winter the predicted global climatic catastrophe that would result from the smoke and dust lifted into the atmosphere by burning cities and petroleum facilities." "The world's scientific community has begun to sound the alarm about the grave dangers posed by depleting the protective ozone shield and by greenhouse warming." "And again, we're taking some mitigating steps." "But again, those steps are too small and too slow." "The discovery that such a thing as nuclear winter was really possible evolved out of studies of Martian dust storms." "The surface of Mars, fried by ultraviolet light is also a reminder of why it's important to keep our ozone layer intact." "The runaway greenhouse effect on Venus is a valuable reminder that we must take the increasing greenhouse effect on Earth seriously." "Important lessons about our environment have come from spacecraft missions to the planets." "By exploring other worlds we safeguard this one." "By itself, this fact more than justifies the money our species has spent in sending ships to other worlds." "It is our fate to live during one of the most perilous and one of the most hopeful chapters in human history." "Our science and our technology have posed us a profound question:" "Will we learn to use these tools with wisdom and foresight before it's too late?" "Will we see our species safely through this difficult passage so that our children and grandchildren will continue the great journey of discovery still deeper into the mysteries of the cosmos?" "That same rocket and nuclear and computer technology that sends our ships past the farthest known planet can also be used to destroy our global civilization." "Exactly the same technology can be used for good and for evil." "It is as if there were a god who said to us:" ""I set before you two ways." "You can use your technology to destroy yourselves or to carry you to the planets and the stars." "It's up to you."" "As of 2000, there were still some 35,000 nuclear weapons in the world." "Hopeful steps in the right direction, but still a long way from the safe planet that Carl Sagan envisioned."