This was one of Carl Sagan’s last books, published in 1994 (by Random House) just two years before his death in 1996. It’s subtitled “A Vision of the Human Future in Space,” though on the inside flap it’s referred to as the “long-awaited sequel to Cosmos,” which had been published in 1980. It’s a Sagan book I’ve had on my shelves since publication, but have never read until now.
It what way was it a sequel?, I’ve always wondered. It’s a big book with lots of glossy pages of photographs and artists’ impressions, as was Cosmos (reviewed here). The earlier book covered the trajectory both of human history of the discovery of the cosmos, and a history of the cosmos itself. The answer is that Pale Blue Dot is at once an update on what we’d learned about the planets and moons of our solar system between 1980 and 1994, and a speculation on how human exploration of those planets and moons might proceed into the far future.
There are two great parts to Pale Blue Dot. The first one is about the now famous photograph taken by Voyager 1 in February 1990, as it left the solar system, its camera turned to look back toward the inner solar system, and to Earth. Our planet is seen as a tiny dot against a band of scattered light rays from the sun. Sagan describes how the photograph came about, and writes this about that photograph – probably the most beautiful paragraphs Sagan ever wrote, and likely the most famous passage from science literature in decades. (These passages are found around the web, but I’ll reproduce them here anyway.)
It might be better to hear Sagan read them, in his calm, soothing, philosophical voice. Some years after the book’s publication, a video was created with Sagan’s reading of these passages, against the signature photograph, and others of Earth, with music by Vangelis (which was so prominent in Cosmos, the TV series). Here’s one: https://www.youtube.com/watch?v=wupToqz1e2g&t=39s. There are others.
Look again at that 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.
It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.
There is an underlying theme here, of concern to Sagan since 1980’s Cosmos, about the potential for humans to destroy themselves, via nuclear war, or environmental destruction. Forty years later, these threats have not disappeared.
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The other great part of this book is Chapter 3, called “The Great Demotions.” It’s about the gradual undermining of human pretensions across human history. Chapter 2 discussed how the ancients assumed Earth was at the center of the universe (and why note?), with the heavens thought perfect, different than the earth. (These were opinions, without evidence; no one cared.) Then came Copernicus, Galileo, and the gradual revelation that nature can be observed, not merely assumed or dictated by a Church. In 1837 parallax finally established that the earth circled the sun, and not vice versa.
Then came one demotion after another.
- By the 17th century the “plurality of worlds” was known. Not even our sun was at the center of the universe. The Milky Way became understood, and then other galaxies were understood. We weren’t at the center of the universe, nor center of any expansion.
- Humans kept wondering how we on Earth might nevertheless be special. Maybe no other stars have planets? No; even as of Sagan’s writing in 1994, 3 planets orbiting a distant star were known.
- Maybe we’re at some special position in time? “It once seemed very reasonable to think of the Universe as beginning just a little before our collective memory is obscured by the passage of time and the illiteracy of our ancestors.” No; evidence of the age of the Earth contradicts the idea.
- Maybe something special the Earth’s motion? No; Einstein denied a “privileged form of reference.”
- Then maybe humans were specially created? No; Darwin came along and showed how natural processes account for our existence.
- Then maybe we’re special because of our reason, ethics, and so on? Yet other animals exhibit some of these traits; we personify animals in children’s stories, and we project our own nature onto Nature.
- Then maybe we’re the only intelligent beings in the universe? Here, we don’t know. But it’s wishful thinking, and arrogance. We’ve barely begun looking (via SETI).
- Then what about the anthropic principle? That the structure of the universe, even if slightly different, could not support life? (Sagan mentions that, in fact, only a vanishingly small amount of our universe, as it is, is compatible with life.) This is Dr. Pangloss in Voltaire. We don’t know what other combinations of physical constants might be possible for other universes to exist.
All of this leads us to conclude that humans have not been given the lead in the cosmic drama.
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More about this book, of a general outline and summary, in a future post.
