The long view
A prime consideration for the Long Now Foundation, and for the cloistered intellectuals in Anathem, is how to ensure the survival of knowledge on millennial timescales. Computers are cool but their value as information storage devices in the long term is unproven, whereas we know that paper, papyrus, and clay tablets can both survive for multiple millennia and--crucially--be decoded by the folks on the other end. In contrast, I have ZIP discs from 2001 that I can't access because I don't have a ZIP drive any more and can't be bothered to get one. My important data has migrated from ZIPs to CDs to an external hard drive and now to several hard drives scattered across the globe. So assuming that I and my friends continue to look after them, my goodies have achieved as much--or as little--longevity as the wired world. That longevity is really the whole question, and I'll get back to it in a moment.
A related concern shared by the Long Now folks and Stephenson: should a given work or body of knowledge be used, which increases the risk that it will be destroyed, deliberately or accidentally, or mutated beyond recognition, or just sealed away for future perusal? As Hillis notes, "The Dead Sea Scrolls managed to survive by remaining lost for a couple millennia. Now that they've been located and preserved in a museum, they're probably doomed. I give them two centuries - tops." Less than that if people start throwing bombs around, which on a long enough timescale is fairly certain. Similarly, inside Anathem's concents--the concentric monasteries surrounding the Millennium Clocks--some topics are taboo because their exploration causes the societies that explore them to stop being long-lived. Reminds me of Paul Graham's hypothesis that innocence is vital to learning.
Since Stephenson had already tripped my brain over into thinking on millennial timescales, I picked up a book that I've been circling around for a few months: Year Million, a collection of essays on how (or if) the post/human civilization will continue for the next million years. Many (but not all) of the contributors assume that we'll eventually dismantle the solar system to construct a Matrioshka brain (ordinary Dyson swarms are so TwenCen) and send out replicators to build Mbrains around other stars. Wil McCarthy has a bracingly hard-edged answer to Fermi's Paradox: we don't see any other civilizations out there because technological progress is so fast compared to biological evolution that the first one out of the gate in any particular galaxy gets the whole pie. The Milky Way is ours, if we can just get off this rock without killing ourselves.
...and now we're back to my ZIP drives. How survivable is our digital knowledge base? Assuming no interruptions, we can just keep copying all of our stuff to the next generation of storage devices and accessing it on the latest version of internet, from now until Mbrain come. But that "assuming no interruptions" is the kicker, ain't it? Interruptions like thermonuclear war--Cold War 1 is over but how long will we territorial apes keep those particular toys in the closet? Or the eruption of the resurgent caldera under Yellowstone, the effects of which would probably be similar to those of an all-out nuclear exchange.
Of course, even an all-out nuclear war between, say, the US, Western Europe, Russia, and China would not mean the end of humanity or civilization or even the wired world. Ever notice how all the nuked-up itchy-trigger-finger countries are in the northern hemisphere? Brazil and Australia might the future superpowers while our descendants in the north literally pull their hair out trying to maintain a medieval standard of living.
It seems, to me, to be an all-or-nothing deal. Either civilization will keep going, somewhere, and we'll get out into space soonish, or we'll do something, or a combination of somethings--nukes, superplagues, Von Neumann nanoweaponry--that will wipe us out.
Let's take option 2 first. I wonder if we are actually capable of wiping ourselves out. Not capable as in willing to pull the trigger, but capable as in actually possessing the means to do so. Let's say that we keep a lid on things for another century or two, until Brazil and South Africa and Australia all have their own huge nuclear stockpiles, and everyone has at least a few cruise missiles armed with multiple-drug-resistant Tb and superanthrax, and we all let go at once. Humans would still survive somewhere. There will be places that are too far down the priority list to be worth bombing, too far off the beaten track to get the superplagues released over the megalopolises, and situated by accidents of climate and geography to avoid the windborn fallout and hypergerms. There are places like that even in the U.S., tracts of land hundreds of miles on a side with no nuke-worthy military installations or population centers, and outside the fallout blanket from any projected nuclear exchange (the government has literally thousands of pages of reports on this stuff).
Even if we somehow wiped out all of our industrialized cities, towns, and even villages, someone out there would make it. On an island in the Pacific, or a cave in Afghanistan, or a valley in the Andes. Even if we got rid of all the humans except that one little town or tribe or clan, they'd eventually expand out and recolonize the globe, just like hominids have been doing for millions of years. And as they spread and diversified they'd find our artifacts, and they'd get industrialized civilization back up and running a lot faster than it took us to get it up and running in the first place.
I notice a lot of futurists mentioning global climate change as a threat to human survival. I'm sorry, but what a load of crap. I'm convinced that AGW is real, and it probably is a threat to many of our nations and institutions, but to our species? Hello, McFly--humans migrated over one pole and colonized two continents, including equatorial rain forests, in the space of a few millennia. And they did it with no tools that weren't readily made from rocks, plants, and animals, no written language, and no domesticated animals besides dogs. Whatever happens with the climate, I'm sure that Homo sapiens, or some variant thereof, will survive. The United States, the globalized economy, and the Internet I'm not quite as sure about, but I would bet on the side of human ingenuity (some would say rapacity) in the face of whatever the Earth throws at us.
So. I think that for the near term--say, the next few centuries or millennia--we are extinction-proof (barring extraterrestrial planet-wreckers, in which case all bets are off). But I don't think it is equally likely that we will get off the planet. I can easily envision a future in which we repeatedly get to the cusp of the space age and then bomb ourselves back into barbarism, over and over again. Technological civilizations will rise and fall and rise and fall, but never quite get enough people and material out of the atmosphere to make it up there, to turn us into a star-faring species. And each collapse will leave the world a little more radioactive and polluted, and with each rise a few more species will be hunted to extinction before conservation re-emerges. It is the survival and successful transmission of knowledge in just that situation that the Long Now Foundation is contemplating. In the world of Anathem, it actually happened--repeatedly.
Before the Renaissance and the Enlightenment, many educated people thought they were living in a debased civilization, which would never regain the knowledge and wisdom of the Golden Age of antiquity. Our future descendants might actually live in such a world. Successive technological civilizations might fail to reach the same heights (literally and metaphorically) as their precursors, because their precursors used up too many of the readily available resources to allow them to do so. But perhaps these nth generation civilizations will also lack the destructive technologies needed for a truly catastrophic collapse. So each rises a little less high, and falls a little less low, and eventually the sine wave of rising and falling civilization flattens out into a steady-state, somewhere between the Dark Ages and the Victorians. Nation-states in that civilization will probably be just as plastic as they are in our world, but their soldiers will ride horses and fight with swords, because all of the oil and coal will be long gone. And so after a surprisingly brief series of flickering florescences, humanity will lurch into the far future the same way it arrived from the distant past, living lives that are nasty, brutish, and short.
Or we get off this rock and go places. I don't see any intermediate possibilities. Either we will lose the ability to travel into space, or someone, somewhere will get a toehold up there and start building colonies. Like Heinlein said, there is no guarantee that it will be America or Russia; if we can't or won't, it may be Turkey or Kenya or anybody else. But someone will go, unless the technological means is taken out of our collective hands, which I think would be impossible without destroying civilization. And even if this technological civilization--by which I mean the globe-spanning one that you are part of--doesn't make it, a future one might, half a millennium from now when the radioisotope load gets low enough that they can plunder what's left at White Sands or Baikonur or Kourou. But we have a better chance than they will, because we still have about half our oil, most of our coal, and none of the memory gaps that go along with nuclear apocalypse.
At this point it is de rigeur to note that we will probably never have the means to move more than a tiny fraction of planet's population off of it. Whatever the spacefarers do, we still have to solve our problems down here on Earth--so goes the refrain. Like AGW, this strikes me as a non-starter when applied to the species. Once the spacefarers have fledged, that is, become self-sufficient--getting their metals from asteroids, water from comets or moons, growing their own crops on their rotating habitats and having babies in one g--they are on the path to the stars (or the Mbrain) regardless of what happens to those who stay in the nest. From that point, they are the cutting edge of human progress, and the clodhoppers down here will have the threat of asteroid bombardment to keep them in line (I'm not saying that's nice, but does it seem hard to believe based on human history?). In fact, both scenarios could play out simultaneously--a long progression of technological civilizations rising and falling on Earth while our descendants build Mbrains around the Pleiades.
So what is the end of all this casting of bones? As Michio Kaku said, "Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying." Similarly, either we are going to get off the planet and become starfarers, or we are not. The terrifying part is that we will probably decide in the next few decades.
Your thoughts are welcome.