Codex Futurius: Chatting With Aliens

Here's another entry in the Codex Futurius project, this blog’s never-ending quest to explore the timeless scientific ideas raised by science fiction. This question about communicating with aliens goes to Jill Tarter of SETI. Thanks again to Jennifer Ouellette, the director the NAS’ Science and Entertainment Exchange (SEEx) program, for connecting us with Tarter. Would/will we recognize an alien transmission right away? Is there a chance we could miss such a transmission, or they ours? We will recognize the sorts of electromagnetic signals for which we have built good matched filters: nanosecond optical laser pulses, narrowband radio continuous wave or pulsed signals. If signals are of some other type (e.g., a modulation scheme with higher dimensionality, or something other than electromagnetic waves) then we will not detect them, except by serendipity as we build new instruments to study our universe in different ways, or by using increasing computational power to ...