I think it was the late science writer Stephen Jay Gould who coined the term “deep time” for the vast panorama opened up to human eyes by the last three hundred years or so of discoveries in geology and astronomy. It’s a useful label for an even more useful concept. In our lives, we deal with time in days, seasons, years, decades at most; decades, centuries and millennia provide the yardsticks by which the life cycles of human societies—that is to say, history, in the usual sense of that word—are traced.
Both these, the time frame of individual lives and the time frame of societies, are anthropocentric, as indeed they should be; lives and societies are human things and require a human measure. When that old bamboozler Protagoras insisted that “man is the measure of all things,” though, he uttered a subtle truth wrapped in a bald-faced lie.* The subtle truth is that since we are what we are—that is to say, social primates whow have learned a few interesting tricks—our capacity to understand the cosmos is strictly limited by the perceptions that human nervous systems are capable of processing and the notions that human minds are capable of thinking. The bald-faced lie is the claim that everything in the cosmos must fit inside the perceptions human beings can process and the notions they can think.
(*No, none of this has to do with gender politics. The Greek language, unlike modern English, had a common gender-nonspecific noun for “human being,” anthropos, which was distinct from andros, “man,” and gyne, “woman.” The word Protagoras used was anthropos.)
It took the birth of modern geology to tear through the veil of human time and reveal the stunningly inhuman scale of time that measures the great cycles of the planet on which we live. Last week’s post sketched out part of the process by which people in Europe and the European diaspora, once they got around to noticing that the Book of Genesis is about the Rock of Ages rather than the age of rocks, struggled to come to terms with the immensities that geological strata revealed. To my mind, that was the single most important discovery our civilization has made—a discovery with which we’re still trying to come to terms, with limited success so far, and one that I hope we can somehow manage to hand down to our descendants in the far future.
The thing that makes deep time difficult for many people to cope with is that it makes self-evident nonsense out of any claim that human beings have any uniquely important place in the history of the cosmos. That wouldn’t be a difficulty at all, except that the religious beliefs most commonly held in Europe and the European diaspora make exactly that claim.
That last point deserves some expansion here, not least because a minority among the current crop of “angry atheists” have made a great deal of rhetorical hay by insisting that all religions, across the board, point for point, are identical to whichever specific religion they themselves hate the most—usually, though not always, whatever Christian denomination they rebelled against in their adolescent years. That insistence is a fertile source of nonsense, and never so much as when it turns to the religious implications of time.
The conflict between science and religion over the age of the Earth is a purely Western phenomenon. Had the great geological discoveries of the eighteenth and nineteenth centuries taken place in Japan, say, or India, the local religious authorities wouldn’t have turned a hair. On the one hand, most Asian religious traditions juggle million-year intervals as effortlessly as any modern cosmologist; on the other, Asian religious traditions have by and large avoided the dubious conviction, enshrined in most (though not all) versions of Christianity, that the Earth and everything upon it exists solely as a stage on which the drama of humanity’s fall and redemption plays out over a human-scaled interval of time. The expansive Hindu cosmos with its vast ever-repeating cycles of time, the Shinto concept of Great Nature as a continuum within which every category of being has its rightful place, and other non-Western worldviews offer plenty of room for modern geology to find a home.
Ironically, though, the ongoing decline of mainstream Christianity as a cultural influence in the Western world hasn’t done much to lessen the difficulty most people in the industrial world feel when faced with the abysses of deep time. The reason here is simply that the ersatz religion that’s taken the place of Christianity in the Western imagination also tries to impose a rigid ideological scheme not only on the ebb and flow of human history, but on the great cycles of the nonhuman cosmos as well. Yes, that would be the religion of progress—the faith-based conviction that human history is, or at least ought to be, a straight line extending onward and upward from the caves to the stars.
You might think, dear reader, that a belief system whose followers like to wallow in self-praise for their rejection of the seven-day creation scheme of the Book of Genesis and their embrace of deep time in the past would have a bit of a hard time evading its implications for the future. Let me assure you that this seems to give most of them no trouble at all. From Ray Kurzweil’s pop-culture mythology of the Singularity—a straightforward rewrite of Christian faith in the Second Coming dolled up in science-fiction drag—straight through to the earnest space-travel advocates who insist that we’ve got to be ready to abandon the solar system when the sun turns into a red giant four billion years from now, a near-total aversion to thinking about the realities deep time ahead of us is astonishingly prevalent among those who think they’ve grasped the vastness of Earth’s history.
I’ve come to think that one of the things that feeds this curious quirk of collective thinking is a bit of trivia to be found in a great many books on geology and the like—the metaphor that turns the Earth’s entire history into a single year, starting on January 1 with the planet’s formation out of clouds of interstellar dust and ending at midnight on December 31, which is always right now.
That metaphor has been rehashed more often than the average sitcom plot. A quick check of the books in the study where I’m writing this essay finds three different versions, one written in the 1960s, one in the 1980s, and one a little more than a decade ago. The dates of various events dance around the calendar a bit as new discoveries rewrite this or that detail of the planet’s history, to be sure; when I was a dinosaur-crazed seven-year-old, the Earth was only three and a half billion years old and the dinosaurs died out seventy million years ago, while the latest research I know of revises those dates to 4.6 billion years and 65 million years respectively, moving the date of the end-Cretaceous extinction from December 24 to December 26—in either case, a wretched Christmas present for small boys. Such details aside, the basic metaphor remains all but unchanged.
There’s only one problem with it, but it’s a whopper. Ask yourself this: what has gotten left out of that otherwise helpful metaphor? The answer, of course, is the future.
Let’s imagine, by contrast, a metaphor that maps the entire history of life on earth, from the first living thing on this planet to the last, onto a single year. We don’t know exactly when life will go extinct on this planet, but then we don’t know exactly when it emerged, either; the most recent estimate I know of puts the origin of terrestrial life somewhere a little more than 3.7 billion years ago, and the point at which the sun’s increasing heat will finally sterilize the planet somewhere a little more than 1.2 billion years from now. Adding in a bit of rounding error, we can set the lifespan of our planetary biosphere at a nice round five billion years. On that scale, a month of thirty days is 411 million years, a single day is 13.7 million years, an hour is around 571,000 years, a minute is around 9514 years, and a second is 158 years and change. Our genus, Homo,* evolved maybe two hours ago, and all of recorded human history so far has taken up a little less than 32 seconds.
(*Another gender-nonspecific word for “human being,” this one comes from Latin, and is equally distinct from vir, “man,” and femina, “woman.” English really does need to get its act together.)
That all corresponds closely to the standard metaphor. The difference comes in when you glance at the calendar and find out that the present moment in time falls not on December 31 or any other similarly momentous date, but on an ordinary, undistinguished day—by my back-of-the-envelope calculation, it would be September 26.
I like to imagine our time, along these lines, as an instant during an early autumn afternoon in the great year of Earth’s biosphere. Like many another late September day, it’s becoming uncomfortably hot, and billowing dark clouds stand on the horizon, heralds of an oncoming storm. We human mayflies, with a lifespan averaging maybe half a second, dart here and there, busy with our momentary occupations; a few of us now and then lift our gaze from our own affairs and try to imagine the cold bare fields of early spring, the sultry air of summer evenings, or the rigors of a late autumn none of us will ever see.
With that in mind, let’s put some other dates onto the calendar. While life began on January 1, multicellular life didn’t get started until sometime in the middle of August—for almost two-thirds of the history of life, Earth was a planet of bacteria and blue-green algae, and in terms of total biomass, it arguably still is. The first primitive plants and invertebrate animals ventured onto the land around August 25; the terrible end-Permian extinction crisis, the worst the planet has yet experienced, hit on September 8; the dinosaurs perished in the small hours of September 22, and the last ice age ended just over a minute ago, having taken place over some twelve and a half minutes.
Now let’s turn and look in the other direction. The last ice age was part of a glacial era that began a little less than two hours ago and can be expected to continue through the morning of the 27th—on our time scale, they happen every two and a half weeks or so, and the intervals between them are warm periods when the Earth is a jungle planet and glaciers don’t exist. Our current idiotic habit of treating the atmosphere as a gaseous sewer will disrupt that cycle for only a very short time; our ability to dump greenhouse gases into the atmosphere will end in less than a second as readily accessible fossil fuel reserves are exhausted, and it will take rather less than a minute thereafter for natural processes to scrub the excess CO2 from the atmosphere and return the planet’s climate to its normal instability.
Certain other consequences of our brief moment of absurd extravagance will last longer. On our timescale, the process of radioactive decay will take around half an hour (that is to say, a quarter million years or so) to reduce high-level nuclear waste all the way to harmlessness. It will take an interval of something like the same order of magnitude before all the dead satellites in high orbits have succumbed to the complex processes that will send them to a fiery fate in Earth’s atmosphere, and quite possibly longer for the constant rain of small meteorites onto the lunar surface to pound the Apollo landers and other space junk there to unrecognizable fragments. Given a few hours of the biosphere’s great year, though, everything we are and everything we’ve done will be long gone.
Beyond that, the great timekeeper of Earth’s biosphere is the Sun. Stars increase in their output of heat over most of their life cycle, and the Sun is no exception. The single-celled chemosynthetic organisms that crept out of undersea hot springs in February or March of the great year encountered a frozen world, lit by a pale white Sun whose rays gave far less heat than today; the oldest currently known ice age, the Cryogenian glaciation of the late Precambrian period, was apparently cold enough to freeze the oceans solid and wrap most of the planet in ice. By contrast, toward the middle of November in the distant Neozoic Era, the Sun will be warmer and yellower than it is today, and glacial eras will likely involve little more than the appearance of snow on a few high mountains normally covered in jungle.
Thus the Earth will gradually warm through October and November. Temperatures will cycle up and down with the normal cycles of planetary climate, but each warm period will tend to be a little warmer than the last, and each cold period a little less frigid. Come December, most of a billion years from now, as the heat climbs past one threshold after another, more and more of the Earth’s water will evaporate and, as dissociated oxygen and hydrogen atoms, boil off into space; the Earth will become a desert world, with life clinging to existence at the poles and in fissures deep underground, until finally the last salt-crusted seas run dry and the last living things die out.
And humanity? The average large vertebrate genus lasts something like ten million years—in our scale, something over seventeen hours. As already noted, our genus has only been around for about two hours so far, so it’s statistically likely that we still have a good long run ahead of us. I’ve discussed in these essays several times already the hard physical facts that argue that we aren’t going to go to the stars, or even settle other planets in this solar system, but that’s nothing we have to worry about. Even if we have an improbably long period of human existence ahead of us—say, the fifty million years that bats of the modern type have been around, some three and a half days in our scale, or ten thousand times the length of all recorded human history to date—the Earth will be burgeoning with living things, and perfectly capable of supporting not only intelligent life but rich, complex, unimaginably diverse civilizations, long after we’ve all settled down to our new careers as fossils.
This does not mean, of course, that the Earth will be capable of supporting the kind of civilization we have today. It’s arguably not capable of supporting that kind of civilization now. Certainly the direct and indirect consequences of trying to maintain the civilization we’ve got, even for the short time we’ve made that attempt so far, are setting off chains of consequences that don’t seem likely to leave much of it standing for long. That doesn’t mean we’re headed back to the caves, or for that matter, back to the Middle Ages—these being the two bogeymen that believers in progress like to use when they’re trying to insist that we have no alternative but to keep on stumbling blindly ahead on our current trajectory, no matter what.
What it means, instead, is that we’re headed toward something that’s different—genuinely, thoroughly, drastically different. It won’t just be different from what we have now; it’ll also be different from the rigidly straight-line extrapolations and deus ex machina fauxpocalypses that people in industrial society like to use to keep from thinking about the future we’re making for ourselves. Off beyond the dreary Star Trek fantasy of metastasizing across the galaxy, and the equally hackneyed Mad Max fantasy of pseudomedieval savagery, lies the astonishing diversity of the future before us: a future potentially many orders of magnitude longer than all of recorded history to date, in which human beings will live their lives and understand the world in ways we can’t even imagine today.
It’s tolerably common, when points like the one I’ve tried to make here get raised at all, for people to insist that paying attention to the ultimate fate of the Earth and of our species is a recipe for suicidal depression or the like. With all due respect, that claim seems silly to me. Each one of us, as we get out of bed in the morning, realizes at some level that the day just beginning will bring us one step closer to old age and death, and yet most of us deal with that reality without too much angst.