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268 SETI has rested on an implicit assumption that extraterrestrials live on planets orbiting stars, analogs of our own home. This assumption may not apply to our own descendants; future humans are likely to spread into interplanetary space. Planets may be a good place for life to begin, Dyson observed, but they are not a likely place for the home of a big technological society. As one study of the space colony concept put it: “In the future, the Earth might be looked upon as an uncomfortable and inconvenient place to live as compared to the extraterrestrial communities.”** The implication is clear: We should investigate nonplanetary locations for finding alien intelligence. If advanced aliens have dispersed to interstellar distances, Shostak rec- ognized, we can expect to find them around stars that might be patently unsuitable for incubating life.*” In the longer run, expansion could free more advanced species from depending on any star; some technological civilizations might choose instead to live in interstellar space. Dyson proposed that bodies such as comets may provide homes for life throughout the Galaxy, not just near stars.” We might have a better chance to find evidence of intelligence if we searched in all directions in a wider range of frequencies. That would place much greater demands on our search systems. Because we search for others, we assume that they search as well. This rests on a belief: that many civilizations at some point in their development perceive the likelihood of other intelligent life in the universe and find themselves technically able to search for and to send signals to it. Bracewel even suggested that advanced communities would act in concert and avoid duplication in searching.”’ How realistic is this assumption? A search cannot be comprehensive i it is confined within a moment in time; it may have to be sustained for eons. Yet, our own searches have been episodic cultural phenomena, dependent on the values, perceptions, and technologies of their eras. Extraterrestrial civilizations—if they ever start a search—may not give it continuing atten- tion over millennia if they do not find anything within a time span tha they consider enough. The most curious—or the least self-satisfied—may be the most likely to find us. However, interstellar communications curiosity may be incident to a particular stage of technological advance; as Campbell suggested, it might give way to other kinds of curiosity with further changes in technol- Before Contact They Live on Planets Orbiting Stars They Search for Others