A book by Stephen Webb with the somewhat cumbersome title If
the Universe Is Teeming with Aliens - Where Is Everybody?: Fifty
Solutions to Fermi's Paradox and the Problem of Extraterrestrial Life tackles the enduring question first posed by Enrico Fermi: our galaxy is big and old and should be teeming with alien civilisations - so where are they? Webb's book is a fun and thought-provoking read (he provides a handy link to a document summarising his ideas here), but why stop at fifty answers? Why not five hundred, five thousand, five million?
The thing about aliens is that the only thing we know about them is that we don't know anything about them. We don't even know if they exist (Webb thinks that they don't). Recent research
explores the possibility of detecting alien civilisations by the air pollution their industries create. It's kind of boggling that we actually have the technology to do this right now, although it only works for planets orbiting uncongenial white dwarf stars, and there might only be a small window of opportunity before the aliens either clean up their act or are strangled by their own effluent. And maybe, unlike us, most civilisations are too smart to produce air pollution in the first place, or perhaps most never go down the industrial road.
When it comes down to it, the question isn't 'why aren't they here?' Instead, it's actually 'are they anything like us?' Could we recognise them, and would they recognise us? If a lion could speak, we would not understand him
, but if he sang we might recognise it as song. We hope that aliens might share something with us: music, mathematics, Marxism, motorways. When we search the sky for signs of life, we're really looking for a mirror.