The Technosignature before SETI

The technosignature has a prehistory. Indeed, there is a history of the technosignature before SETI. And it long predates the invention of the radio telescope. Here I draw from research related to my book-in-progress, The Astrobiological Turn, to sketch a genealogy of the technosignature. I uncover the conceptual and cultural elements that have only recently been combined to form the technosignature as we know it: a tool in the empirical search for extraterrestrial intelligence. My contention is that the scientific search for technosignatures belongs to a tradition fundamentally concerned with the question, What is technology? SETI inherits some of its most basic assumptions from earlier efforts to answer this question, some of which (in the West) go back to the beginning of philosophy in ancient Greece, and even further back to myth. By recovering the genealogy of the technosignature, we can evaluate the complex ways that different elements of the legacy variously inform current SETI science. I tell three episodes from this history. The first is the myth of Prometheus (as told by Hesiod, Aeschylus, and Plato), which constitutes one of SETI’s deep cultural roots. It exbibits an uncanny affinity to the search for technosignatures: it is a creation myth that identifies the very origin of humanity with the acquisition of technology from ancient, powerful beings that live in the heavens. SETI is informed by a Promethean inheritance. Next, I turn to Aristotle, who begins his Physics by defining nature itself (physis). To get at the essence of nature, Aristotle asks what distinguishes all objects we consider artificial, which he places in the category of techne, from everything that seems to arise “by nature”—like flowers, and animals. His answer might have been developed by a contemporary theorist of the technosignature: Artificial objects come into existence thanks to a causal factor that intervenes within, and modifies, processes that would otherwise would have unfolded according to the principles of motion that define them. Hammers don’t just happen the way flowers just grow. Tools must be constructed by something else. That “something else” is intelligence. Aristotle’s distinction between physis and techne persists in the contemporary search for technosignatures. The protagonist of the last episode is the philosopher Immanuel Kant, who, in his 1790 Critique of Judgment, added to Aristotle’s definition of techne a systematic reflection on the diagnostic signatures by which inanimate, biological, and technological systems can be identified. Indeed, at the turn of the nineteenth century, Kant developed a theoretical approach to both the biosignature and the technosignature. I conclude by bringing Prometheus, Aristotle, and Kant into contact with current work in SETI. At stake is a single question: to what extent does contemporary science break with this legacy? Even the slightest hairline fracture of a conceptual difference might be pried open into a totally new paradigm.