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.
