Martin Rees

OUR FINAL CENTURY

Will the human race survive the twenty-first century?

Martin Rees is the Astronomer Royal, a highly respected cosmologist who has previously give us a number of fine books on the nature of the universe. This book is different from those he has written hitherto, for it focuses on us here on Earth and what we can hope for, or fear, in the rest of this century. It has to be said that it makes grim reading. In a radio discussion I heard recently Rees agreed that he should perhaps have appended a question mark to his main title, which might have made me feel a bit better after reading it, but not much; he does not rate the chances that our civilization will outlast the century as better than fifty-fifty.

Throughout most of the second half of the twentieth century the biggest risk we faced was nuclear war. Like others before him, Rees thinks we were lucky on several occasions that this did not happen; the Cuban missile crisis of 1962 was the most glaring instance of this but there were others. When the Cold War ended many people assumed that the threat had receded almost into insignificance, but September 11th put a decisive end to any complacency on that score; the danger that terrorists might get hold of nuclear material to make either an actual nuclear device or else a "dirty" bomb is now frequently on the lips of our leaders. Terrorists could also, as we know, acquire chemical or biological material with nefarious intent. In writing about these fears Rees is doing no more than reiterate what we are constantly being told in newspapers, on television, and on the radio.

It isn't only the threat from terrorists that we need to worry about; there is also the increasing possibility that some new technological advance will lead to unforeseen results. Prince Charles has recently been alarmed by the thought that nanotechnology might reduce the whole biosphere to "grey goo", and though this seems a bit too much like science fiction to be credible Rees does not feel able to dismiss it out of hand. But we should be a lot more concerned about the potential misapplication of technology that already exists or is likely to do so within the next 20 years. The rather dubious comfort that Rees feels able to offer us is that if these short-term fears are realized we shall not have to worry about being taken over by supercomputers or nanomachines in the more remote future since technology will never have the chance to reach that state.

Perhaps the biggest problem that we shall soon face is the ever-increasing dissemination of knowledge about how to make biological and chemical weapons. As Rees remarks, thousands or even millions of individuals may shortly acquire the ability to make and deploy such agents. A few adherents of a death-seeking cult, or even a single individual, could do this. The presently occurring dissemination of computer viruses offers a model for this; soon it may be biological viruses. (Just a few weeks ago a BBC reporter showed that it was easy to download instructions for making sarin nerve gas from the Internet and to obtain the ingredients, quite legitimately, in Britain.) Rees tells us that he has made a thousand-dollar wager, which he does not expect to lose, that a million people will die in a terrorist or ecological catastrophe within twenty years.

As if all this were not enough, we face potential dangers on the larger scale as well. Global warming is of course familiar to everyone by now, though this is something that is at least partially within our own control; we could reduce its effects if not prevent them altogether. There are other possibilities that lie largely or wholly outside our control: impacts from meteors, asteroids, or comets and huge volcanic eruptions or earthquakes, for example, though most of these are so rare that it is hardly worth worrying about them. Even more unlikely scenarios are also conceivable. When the first atomic bomb was being built there seemed a remote possibility that detonating it might spark a chain reaction that would ignite the whole atmosphere or oceans. Something similar might theoretically occur if an experiment in a huge particle accelerator went wrong: it could generate a black hole that would suck everything into it or the quarks it produced could reassemble themselves into a very compressed object called a strangelet, capable of converting anything it encountered into a strange new form of matter. Most far-fetched of all is the risk that a phase transition could spread like an expanding bubble at the speed of light, engulfing not only the Earth but the entire galaxy and beyond. (This is the theme of Stephen Baxter's science fiction novel Time.)

Another way of reaching a pessimistic outlook on humanity's future has been suggested by Brandon Carter and others, who argue on statistical grounds that it is unlikely that the human race will last much longer, at least in its present form (perhaps it will be transformed into something different). Rees does not seem to be entirely convinced by arguments of this kind but admits that it is not easy to say why they are flawed.

This is clearly a very important book, which we should hope is being read by our political leaders. Unfortunately Rees is better at identifying the dangers that face us than he is at offering solutions, but that, no doubt, is a consequence of the situation in which we find ourselves; perhaps there are no solutions. His main suggestion is that we may need to accept the need for vastly increased and intrusive surveillance, with all its implications for restriction of personal freedom. He seems ready to contemplate this. Another idea would be to seek to limit scientific progress in potentially dangerous areas, but the problem with this is that major scientific advances are unpredictable, nor can their applications be foreseen.

Perhaps in an attempt to lighten the gloom, Rees turns in his final pages to look at the possibilities for space exploration if we do happen to survive. Does life, intelligent or otherwise, exist outside Earth, and shall we ever be able to detect it if it does? If it does not, our own significance as the only intelligent species in the galaxy becomes all the greater. "The theme of this book is that humanity is more at risk than at any earlier phase in its history. The wider cosmos has a potential future that could even be infinite. But will these vast expanses of time be filled with life, or as empty as the Earth's first sterile seas? The choice may depend on us, this century."

Attempts to extrapolate from present-day science and technology to future developments are notoriously liable to be falsified by events. But most of the dangers that Rees writes about are already with us, at least in their early stages. Even if total collapse of our civilization does not occur, some at least of the bad things Rees foresees appear all but inevitable. It is therefore very likely that he will win his wager (though of course he may not be around to collect it).

9 June 2003

Related review: Countdown To Apocalypse (Paul Halpern)