The Badlands

Where NOT to Seek Little Green Men

ABOUT a million man-years has now gone into the Seti at Home project, the personal computer search for alien civilisation, and I would wager that in its present form it will not succeed. For the Seti data, sifted daily by three million PCs (including my own), is taken in the most part from those regions of the universe that are least likely to harbour intelligent aliens.  Most of it comes from recorders that ``piggy back'' on the fixed dish Arecibo radio telescope in Puerto Rico. Because this huge machine looks at the cosmos randomly, it tends to observe far more of the spectacular regions of the galaxy that interest physicists than those few dull ones that might attract biologists.

The Arecibo 305 Meter Radio Telescope

If radio astronomers can be divided into these two classes, then what bores one fascinates the other, and vice versa. The localities of the most exciting objects in the sky, the Pleiades, the Belt of Orion, the fiery nebulae, the globular clusters, the supernova remnants, the newly-discovered fiery Hubble-V nebula in the galaxy NGC 6822, and the densest parts of the Milky Way, would, over long time scales, all be subjected to lethal radiation. There would be little likelihood of inhabited planets. In short, very large parts of the universe are inherently hostile to native life. Just as our entire solar system, except for Earth, is probably void of animals more complex than jellyfish, so most of the galaxy, and therefore most of most galaxies seem to be no-go areas for little green men. Only when Seti becomes rich enough to build its own telescopes and point them where it wishes are we more likely to find out who lives where. Take the obvious example of our own cosmic environment. From far off, the Sun and its neighbouring stars would look extraordinarily dull. As the late Douglas Adams remarked: ``Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the galaxy lies a small unregarded yellow sun.'' Yet around one of these stars advanced life has flourished, and such unfashionable places as these may be the most promising places to find it. It used to be confidently asserted, by Carl Sagan and others, that our galaxy is likely to contain about six million alien civilisations. As we learn how deadly most of space is, perhaps this estimate should be revised downwards to six. This is not necessarily bad news for mankind's future. Uninhabited worlds need not mean uninhabitable worlds. While the evolution of complex species takes billions of years and can be fatally interrupted at any time, no such stricture threatens the settlement and colonisation of planets, if carried out by a species that evolved somewhere else. An environment that was lethal over billions of years might be perfectly safe for a few millennia. Take the star-packed galactic centre in Sagittarius, the site of the imperial planet Trantor in Isaac Asimov's novel The Foundation Trilogy. An unlikely place for native life could be a most suitable one for immigrants.