The most attractive habitats for synthetic sentience might be the vicinities of exceptional sources of energy - for example black holes, or even the neighbourhoods of large stars, which routinely boil off the energy of ten thousand suns. These are the destinations they may seek.

Despite tantalizing suggestions of fossilized microbes in meteorites, puzzling and possibly biogenic methane gas in the martian atmosphere, and a long-standing controversy over the Viking lander experiments of nearly 40 years ago, there's still no Exhibit A that points unequivocally to biology in our own back yard.

While human space travel is daunting, machines - with their indefinitely long lifetimes - could travel the galaxy. It might make little difference to them that bridging the distance from one star to the next could take hundreds of thousands of years or more.

Seth Shostak Quotes