Spacetime Odyssey

01

Standing Up in the Milky Way

02

Some of the Things That Molecules Do

03

When Knowledge Conquered Fear

04

A Sky Full of Ghosts

05

Hiding in the Light

06

Deeper, Deeper, Deeper Still

07

The Clean Room

08

Sisters of the Sun

Stars to dust, and dust to stars. In the cosmos, nothing is wasted.

Our ancestors worshipped the Sun. And they were far from foolish. It makes good sense to revere the Sun and stars because we are their children. The silicon in the rocks, the oxygen in the air, the carbon in our DNA, the iron in our skyscrapers, the silver in our jewelry, were all made in stars billions of years ago. Our planet, our society and we ourselves are stardust.

If it (visible light) should strike the surface of a leaf, it will be stored in the plant as chemical energy. Sunshine into Moonshine (a type of Whiskey). I can feel my brain turning the chemical energy of the wine into the electrical energy of my thoughts and directing my vocal cords to produce the acoustic energy of my voice. Such transformations of energy are happening everywhere all the time. Energy from our star drives the wind and the waves and the life around us. How lucky we are to have this vast source of clean energy falling like manna from heaven on all of us.

There is no refuge from change in the cosmos.

09

The Lost Worlds of Planet Earth

The Permian. The Great Dying. The closest life on Earth has ever come to annihilation. Nine in ten of all species perished. It took a long time for life to bounce back. For a few million years, Earth could have been called the Planet of the Dead. We are descended from one of the few species that managed to squeak by. You are human and alive at this very moment because they (mammals) managed to endure, conveying their DNA through one of the most treacherous periods in the history of life.

Wherever you walk on Earth, lost worlds lie buried beneath your feet.

There is nothing like an interglacial period, one of those balmy intermissions in an ice age. And the great news is that this one is due to last for another 50,000 years. What a break for our kind. Just one problem. We can't seem to stop burning up all those buried trees from way back in the Carboniferous Age, in the form of coal; and the remains of ancient plankton, in the form of oil and gas. If we could, we'd be home free, climate-wise. Instead, we're dumping carbon dioxide into the atmosphere at a rate the Earth hasn't seen since the great climate catastrophes of the past, the ones that led to mass extinctions. We just can't seem to break our addiction to the kinds of fuel that'll bring back a climate last seen by the dinosaurs; a climate that will drown our coastal cities and wreak havoc on the environment and our ability to feed ourselves. All the while, the glorious sun pours immaculate, free energy down upon us; more than we will ever need. Why can't we summon the ingenuity and courage of the generations that came before us? The dinosaurs never saw that asteroid coming. What's our excuse?

Congratulations. You are alive. There is an unbroken thread that stretches across more than three billion years that connects us to the first life that ever touched this world. Think of how tough, resourceful, and lucky all our countless ancestors must have been to survive long enough, to pass on the message of life to the next, and the next, and the next generation, hundreds of millions of times before it came to us. There were so many rivers to cross, so many hazards along the way. Predators, starvation, disease, miscalculation, long winters, drought, flood, and violence. Not to mention the occasional upheavals that erupted from within our planet and the apocalyptic bolts that come from the blue. No matter where we hail from or who our parents were, we are descended from the hearty survivors of unimaginable catastrophes. Each of us is a runner in the longest and most dangerous relay race there ever was, and at this moment, we hold the baton in our hands.

The past is another planet. And so is the future.

10

The Electric Boy

Nothing is too wonderful to be true, if it be consistent with the laws of nature.

11

The Immortals

What is the life expectancy of a civilization? By the time of Enheduanna, the first person to ever get a writing credit, civilization was already more than 1,000 years old. But today, her glorious city is a barren wasteland. What went wrong? One problem was the almost ceaseless warfare between the cities of Mesopotamia, which continually destroyed their achievements. They glorified military conquest and ultimately became its victims. Another cause of decline was that their technical know-how overran their understanding of nature. The ingenious irrigation system that was the basis for the great civilizations of Mesopotamia had an unintended consequence…the water channeled into their farmlands every year evaporated and left its salt behind. Over generations, the salt accumulated and began to kill the crops. And then, about 2,200 BC, not long after the time of Enheduanna, disaster struck…a drought of truly epic proportions, lasting for many decades. Rains stopped, crops withered, and there was famine and anarchy. Barbarians invaded. The streets of many cities were littered with dead. There could be only one explanation. Enlil, the supreme god, was angry because one of his temples had been destroyed. The people of Mesopotamia could not know that the same drought was crushing the dawning civilizations of Egypt, Greece, India, Pakistan, and China. All the gods of the Earth must have been really angry about something. For all their brilliance, the people of those civilizations had no inkling they were experiencing abrupt climate change.

Human events entail too many variables, too many uncertainties, to make scientific statements about our future. But we can still dream. The next golden age of human achievement begins here and now. New Year's Day of the next cosmic year. In the first tenth of a second, we take the vision of the pale blue dot to heart and learn how to share this tiny world with each other. The last internal combustion engine is placed in a museum, as the effects of climate change reverse and diminish. A fifth of a second into this future, people will stop dying from the effects of poverty. The planet is now a completely self-sustaining, intercommunicating organism. A half-second from now, the polar ice caps are restored, to the way they were in the 19th century, and the forecast is mild and pleasant for the next cosmic minute and a half…40,000 years. By the time we are ready to settle, even the nearest other planetary systems, we will have changed. The simple passage of so many generations will have changed us. Necessity will have changed us. We are an adaptable species. It will not be we who reach Alpha Centauri and the other nearby star systems on our interstellar arks. It will be a species very like us but with more of our strengths and fewer of our weaknesses; more confident, far-seeing, capable, and wise. For all our failings, despite our flaws and limitations, we humans are capable of greatness. What new wonders, undreamt of in our time, will we have accomplished in another generation and another? How far will our nomadic species have wandered by the end of the next century, and the next millennium? Our remote descendants, safely arrayed on many worlds throughout the solar systems and beyond, will be unified by their common heritage, by their regard for their home planet, and by their knowledge that, whatever other life may be, the only humans in all the universe came from Earth. They will gaze up and strain to find the blue dot in their skies. They will marvel at how vulnerable the repository of all our potential once was, how perilous our infancy, how humble our beginnings, how many rivers we had to cross before we found our way.

12

The World Set Free

The Earth is alive. It breathes…but very slowly. A single breath takes a whole year. The forests contain most of Earth's life, and most forests are in the Northern Hemisphere. When spring comes to the north, the forests inhale carbon dioxide from the air and grow, turning the land green. The amount of CO2 in the atmosphere goes down. When fall comes and the plants drop their leaves, they decay, exhaling the carbon dioxide back into the atmosphere. The same thing happens in the Southern Hemisphere at the opposite time of the year. But the Southern Hemisphere is mostly ocean. So it's the forests of the north that control the annual changes in the global CO2. The Earth has been breathing like this for tens of millions of years.

Climate has changed many times in the long history of the Earth but always in response to a global force. The strongest force driving climate change right now is the increasing CO2 from the burning of fossil fuels, which is trapping more heat from the Sun. All that additional energy has to go somewhere. Some of it warms the air. Most of it ends up in the oceans. All over the world, the oceans are getting warmer. It's most obvious in the Arctic Ocean and the lands that surround it. Okay, so we're losing the summer sea ice in a place where hardly anyone ever goes. What do I care if there's no ice around the North Pole?

Ice is the brightest natural surface on the Earth, and open ocean water is the darkest. Ice reflects incoming sunlight back to space. Water absorbs sunlight and gets warmer, which melts even more ice, which exposes still more ocean surface to absorb even more sunlight. This is what we call a positive feedback loop. It's one of many natural mechanisms that magnify any warming caused by CO2 alone.

The Apollo missions were conceived as a demonstration of the superior power and precision of our strategic missiles. But a funny thing happened to us…on our way to the Moon. We looked homeward and discovered another world…our own. For the first time, we inhabitants of Earth could step back and see it as it really is…one world, indivisible, and kind of small in the cosmic context. Whatever the reason we first mustered the enormous resources required for the Apollo program, however mired it was in Cold War nationalism and the instruments of death, the inescapable recognition of the unity and fragility of the Earth is its clear and luminous dividend, the unexpected gift of Apollo. A project conceived in deadly competition made us recognize our community.

13

Unafraid of the Dark

Our ancestors believed the universe was made for them. It was natural to assume that we were at the center. After all, it looks like the Sun and stars all revolve around us. We still speak of the Sun "rising." The architecture of our language, myths and dreams comes from that pre-scientific age.

There seems to be a mysterious force in the universe, one that overwhelms gravity on the grandest scale to push the cosmos apart. Most of the energy of the universe is bound up in this unknown force. We call it "dark energy," but that name, like "dark matter," is merely a code word for our ignorance. It's okay not to know all the answers. It's better to admit our ignorance than to believe answers that might be wrong. Pretending to know everything closes the door to finding out what's really there. Tonight, our ships sail into even more exotic waters.

Become an extraterrestrial archaeologist for a few moments. An artifact has been finished out of the interstellar ocean. It was made by beings that lived about a billion years ago. What would you make of them and their world? They've sent us their music and greetings in 59 human languages. And one whale language. And a sound essay that includes a Saturn V rocket launch. A mother's first words to her newborn baby. The brain waves of a young woman newly fallen in love. And the sound of a pulsar. All of that will live for a billion years.

How long is a billion years? If you compress all the time since the Big Bang, the explosive birth of the universe, into a single Earth year, a billion years is about one month of that year.

What was happening on Earth a billion years ago? Most of Earth's land was amassed into a supercontinent called Rodinia. It was a barren desert… no animals, no plants. A billion years ago, there wasn't enough oxygen in our atmosphere to form an ozone layer, and without it, ultraviolet radiation prevented life from colonizing the land. Rodinia probably looked more like Mars than present-day Earth. The giant world ocean produced huge rainstorms causing flooding and erosion. Glaciers formed, and their slow but relentless movements carved the land into new shapes. Single-celled organisms dominated the oceans, but some existed in colonies called "microbial mats," and the first multicellular organisms would soon evolve. And a billion years from now, what will Earth be like…long after our cities, the Egyptian pyramids, the Rocky Mountains have all been eroded to dust? There are few things we can say with confidence about such a far distant time. The only thing we can say for sure is that Earth as we know it will be so changed that we would scarcely recognize it as home. But even a thousand million years from now, something of who we were and the music that we made in that long-ago spring will live on.

…the pale blue dot. That's here. That's home. That's us. On it, everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every superstar, every supreme leader, every saint and sinner in the history of our species, lived there…on a mote of dust…suspended…in a sunbeam. The Earth is a very small stage in a vast, cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that in glory and triumph they could become the momentary masters of a fraction…of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner. How frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet…is a lonely speck in the great, enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves. The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment, the Earth is where we make our stand.