The search for extraterrestrial intelligence stands out in the quest to find life elsewhere because it assumes that certain kinds of life will manipulate and exploit its environment with intention. And that intention may go far beyond just supporting essential survival and function. By contrast, the general search for other living systems, or biosignatures, really is all about eating, reproducing and, not to put too fine a point on it, making waste.
The assumption of intention has a long history. Back in the late 1800s and early 1900s the American astronomer Percival Lowell convinced himself, and others, of “non-natural features” on the surface of Mars, and associated these with the efforts of an advanced but dying species to channel water from the polar regions. Around the same time, Nikola Tesla suggested the possibility of using wireless transmission to contact Mars, and even thought that he might have picked up repeating, structured signals from beyond the Earth. Nearly a century earlier, the great mathematician and physicist Carl Friedrich Gauss had also thought about active contact, and suggested carving up the Siberian tundra to make a geometric signal that could be seen by extraterrestrials.
Today the search for intention is represented by a still-coalescing field of cosmic “technosignatures,” which encompasses the search for structured electromagnetic signals as well as a wide variety of other evidence of intentional manipulation of matter and energy—from alien megastructures to industrial pollution, or nighttime lighting systems on distant worlds.
But there’s a puzzle that really comes ahead of all of this. We tend to automatically assume that technology in all of the forms known to us is a marker of “advanced” life and its intentions, but we seldom ask the fundamental question of why technology happens in the first place.
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