On The Brink Of Eternity
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On the Brink of Eternity
We may be but a blip on the cosmological timeline, but we are uniquely positioned to shape the here, the now, and the far future if there is one.
by Sir Martin Rees
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One hackneyed anecdote among astronomy lecturers describes a worried questioner asking, How long did you say it would be before the sun burnt the Earth to a crisp? Upon receiving the answer, 6 billion years, the questioner responds with relief: Thank God for that, I thought you said 6 million. What happens in far-future eons may seem blazingly irrelevant to the practicalities of our lives. But the cosmic context is not entirely irrelevant to the way we perceive our Earth and the fate of humans; indeed, it actually strengthens our concerns about what happens here and now because it offers a vision of just how prodigious lifes future potential could be.
Most people have little conception or awareness of the far future. Our concerns naturally focus more insistently on the fate of our present generation. Economic decisions generally discount into insignificance what may happen more than twenty years from now, and government decisions are often as short-term as the next election. Sometimes, in energy policy, for example, the horizon extends to fifty years, while the debates about global warming that led to the Kyoto Protocol took cognizance of what might happen 100 to 200 years ahead.
Despite our generally narrow time horizons, the stupendous time spans of the evolutionary past are now part of common culture. And still vaster time spans lie ahead. The sun has been shining for 4.5 billion years; it will continue to shine for another 6 billion years before the fuel runs out, it swells up, and blows off its outer layer. More time lies ahead for our Earth than has so far elapsed.
To properly conceive these vast tracts of time, future as well as past, an analogy can help. Suppose our solar systems entire life cycle were to be represented by a westward walk across the United States, starting in New York at the suns birth in a cosmic cloud and ending in California at the time of the suns terminal flare-up. To pace yourself on this walk, youd need to take one step every 2,000 years. All recorded history would be a mere few steps. Moreover (and this is the important point), these few steps would be before the halfway stage, somewhere in Kansas perhaps.
Theres an unthinking tendency to imagine that humans will be there to witness the suns demise. But it will not be humans: It will be creatures as different from us as we are from bacteria. Long before the sun finally licks the Earths face clean, posthuman intelligence may have spread far beyond its original planet, taking forms that might see the destruction of our Earth as a minor or sentimental matter, and still looking forward to a long-range future. The cosmic future extends far beyond the demise of the sun; the wider cosmos may have an infinite future ahead of it. We cant predict what role life will eventually carve out for itself: It could become extinct, or it could achieve such dominance that it could influence the entire cosmos.
Such speculations have generally been left to science fiction writers. Yet Charles Darwin himself noted, not one living species will transmit its unaltered likeness to a distant futurity. Evolution is speeding up; substantial progressive change within a single lifetime is a distinctive hallmark of recent centuries. Whatever else may have changed over preceding centuries, humans haventnot for thousands of years. Yet biotechnology is now, quite suddenly, opening up an unprecedented new dimension of change. The biological fundamentals of humanity, essentially unaltered throughout recorded history, could be transformed within a century. Targeted drugs, genetic modification, and, perhaps, silicon implants in the brain may change human beings themselvestheir minds and attitudes, even their physiques. Thats something qualitatively new in our history.
When projecting 100 years ahead, we should keep our minds open, or at least ajar, to things that seem beyond the fringe of science fiction. We can plausibly predict some trends extending at least to 2020. Miniaturization, though already amazing, is very far from its theoretical limits. Each tiny circuit-element of a silicon chip contains billions of atoms, making it exceedingly large and coarse compared to the smallest circuits that could in principle exist. One long-term hope is to assemble nanostructures and circuits bottom up by sticking single atoms and molecules together. This is how living organisms grow and develop. And its how natures computers are made: An insects brain has about the same processing power as a powerful present-day computer.
In future centuries, robots and fabricators could pervade the entire solar system. Whether humans will have joined this diaspora is hard to predict. If they did, communities would develop in a manner that eventually made them quite independent of the Earth. Unconstrained, some would surely exploit the full range of genetic techniques and diverge into new species. The diverse physical conditionsvery different on Mars, in the asteroid belt, and in the still colder far reaches of the solar system would give renewed impetus to biological diversification.
The entire galaxy, extending for a hundred thousand lightyears, could be greened in less time than it took for us to evolve from the first primates. Future life could display even more variety than has been played out in the entire annals of the Earths biosphere. Artifacts created by us, and in some way descended from us, may use their own intelligence to develop further, on Earth and far beyond. The post-human potential is immense, so immense that not even the most misanthropic among us would countenance its being foreclosed by human actions. Yet, as the great biologist Christian de Duve wrote, What will happen depends to some extent on us, since we now have the power of decisively influencing the future of life and humankind on Earth.
About 4.5 billion years have elapsed since our sun condensed from a cosmic cloud. A swirling disk of gas encircled the proto-sun. Dust in this disk agglomerated into a swarm of orbiting rocks, which then coalesced to form the planets. One of these became our Earththe third rock from the sun. The young Earth was buffeted by collisions with other bodies, some almost as large as the planets themselves. One such impact gouged out enough molten rock to make the moon. Conditions quieted and the Earth cooled, setting the scene for the emergence of the first life; for more than a billion years, oxygen accumulated in the Earths atmosphere, a consequence of the first unicellular life. Thereafter, there were slow changes in the vegetation and the shape of the landmasses as the continents drifted.
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