Could the first confirmed signal from an extraterrestrial source be less a hello than a goodbye? Astrophysicist David Kipping argues as much, and his “Eschatian Hypothesis” reimagines the way scientists might approach the search for extraterrestrial life. Drawing on centuries of astronomical advancement, Kipping makes the case that the first signs of alien technology we encounter will probably be few, extreme, and atypical-most likely emanating from a civilization in its final stages.
Detection bias is a well-established concept in astronomy. The first discoveries in a new field are usually the brightest or most unusual examples, not the most common. For example, the first exoplanets were discovered orbiting pulsars, whose precisely timed radio pulses make even minor perturbations detectable. However, out of more than 6,000 known exoplanets, fewer than ten are pulsar planets. Similarly, about a third of stars bright enough to be seen with the naked eye are giant stars, even though less than one percent of all stars are actually giants-another classic example of Malmquist bias.
Kipping generalizes this principle to technosignatures. If the energy output of extraterrestrial civilizations is distributed according to a broad, non-Gaussian function, those that are in “loud” phases will be detectable over considerably larger volumes of space. His illustrative model in this paper suggests that if such a civilization spends only one-millionth of its lifetime in a loud state, it must radiate at least one percent of its total lifetime energy budget during that phase if it is to be appreciably more detectable than a quiet one. The massive burst in energy could arise from catastrophic instability, such as environmental collapse or conflict, or may reflect a deliberate attempt to broadcast a plea for help.
Historical signals, such as the famous 1977 Wow! signal, fit intriguingly into this framework. Detected by the Big Ear Radio Observatory, the Wow! signal consisted of a strong, narrowband radio burst that lasted 72 seconds and has never been repeated despite considerable follow-up observations. Natural hypotheses have been advanced recently, including superradiance from neutral hydrogen clouds excited by an exotic astrophysical object. However, Kipping posits that it could have been a transient technosignature of a civilization reaching its demise.
The Eschatian Hypothesis has direct implications for SETI strategy. Traditional searches often focus on narrowly defined technosignatures-specific frequencies, modulation patterns, or laser pulses. Kipping instead promotes “agnostic anomaly detection,” where wide, unique transients are sought in flux, spectrum, or apparent motion that naturally resist conventional explanation. Wide-field, high-cadence surveys are well-suited to this approach, since they can capture short-lived events before they dissipate.
Facilities like the Vera C. Rubin Observatory are destined to revolutionize this research. The 3.2-gigapixel camera on Rubin, the largest ever built for astronomy, will survey the entire visible sky every few nights, and the time-domain dataset that results will be replete with transient events. Though designed with a different purpose in mind supernovae, variable stars, and near-Earth objects Rubin’s strengths align remarkably well with an Eschatian approach. It is likely that its continuous monitoring could reveal high-intensity, one-time events; perhaps these are the “loud shouts in the night” from civilizations in crisis.
Detection bias also suggests that even if the galaxy hosts tens of thousands of stable, sustainable civilizations, their subtle technosignatures may be overpowered by rare but conspicuous outliers. Kipping points out that advanced civilizations may eventually “become indistinguishable from nature” and leave no detectable trace. By contrast, unstable civilizations may blow through enormous stores of energy over short periods and produce signals orders of magnitude brighter than their quiet counterparts. The Eschatian Hypothesis reframes the romance of first contact for space enthusiasts and amateur astronomers alike. Instead of speculating on a serene exchange of knowledge, that first alien signal might be a brief, intense flare-a technological supernova signaling the end of the world. And when such a signal does arrive, it is not likely to be picked up by a single dish listening on a narrow frequency but discovered in the broad, sweeping gaze of sky surveys that identify anomalies before they vanish into cosmic silence.
