Astronomy has a habit of bringing new worlds with their weirds. The initial exoplanets were found orbiting a pulsar, not a Sun-like star- an early victory which was only possible because pulsars have such a good sense of time that even small tugs would be visible. The recent confirmed exoplanet count of 6,052 has eight new exoplanets around pulsars, making it one more time known that exoplanet “firsts” are often detected by the most detectable, not the most common.
That mere lesson underlies a very simple rewording of the first identified technosignature by astrophysicist David Kipping, the so-called, “Eschatian Hypothesis.” The proposal does not consider early contact as a probable interaction between two societies that are stable. Rather, it approaches it as an observational issue: the earliest technology that will be observed in interstellar distances will be the technology most easily observable.
The naked-eye sky is already distorted by detection bias. Thirds of all stars that can be seen with the naked eye are evolved giants, despite the fact that only one percent of all stars are in the evolved giant stage. The difference is not the cosmic favoritism; it is geometry and brightness. Extravagant objects can be sensed within a much greater volume, thus they are what catches the eye first. This reasoning carries over to explain the regular observation of thousands of supernovae per year by astronomers despite the fact that a galaxy similar to Milky Way only rarely emits them over periods of centuries.
Kipping applies the same reasoning to so-called “loud” civilizations, which briefly create a technosignature that is much brighter than that of the rest of the background. A very loud civilization only active as a civilization one-millionth of its lifetime will be most likely to be detected first: a civilization that spends a disproportionate portion of its energy budget on brief bursts during the loud window, about one percent of its lifetime energy budget. Detectability increases rapidly with brightness even with a more common quieter civilization since the volume searchable increases with distance.
This is where the romance of SETI is more technical and in some sense more sobering. When advanced human societies are fashioned to move toward efficiency, little waste, and balance with their surroundings, the impressions they leave may vanish into the mundane cycles of the atmosphere and the stars. That is why, the most conspicuous stage in the development of a civilization may not be its adult life but the period of instability, when energy consumption has soared, systems are overheated, or action is brieflived and easy to overlook. This does not mean that we are likely to collapse, but rather that quiet competence is observationally disadvantaged.
The iconic Wow! signal of 1977 still serves as the benchmark of such thinking: a 72-second S band burst, almost on the neutral hydrogen line, which has never been revisited. Recent studies have claimed that a natural process, superradiance in neutral hydrogen clouds can, given the appropriate trigger, cause a short burst of emission that can resemble an artificial beacon. Other treatments have investigated constructed explanations without explicit greeting, such as sweeping beams, whose geometry so discourages repetition. In any case, the similarity here is that it is uncomfortable to any person who is anticipating a consistent carrier signal: the optimal first candidate can be the one that is not available when on demand.
Strategy follows physics. Instead of filtering further and further to preselected frequencies and modulation plans, within the Eschatian framing broad hunting of anomalies is preferred: transients in flux, spectrum, or apparent motion which do not lend themselves to standard astrophysical classification. That style is the one that is consistent with contemporary survey astronomy, where the sky is no longer regarded as a map of locations, but as a moving data stream.
The LSST-era operations of Rubin Observatory are so designed: all data are sent to a common survey data set, which is then acted on to produce alert products and time-series products, with quick follow-up intended. Practically, therefore a technosignature trigger need not be a one-time event at night, but a pattern that appears on several nights in a row, an unphysical sequence of brightness, colour, or location that lasts long enough to be registered, but not long enough to be overlooked.
Should the initial known technosignature come in, the technical task can be less of interpreting a message, and more of a pulse in an ocean of natural fireworks, a pulse that must be shown not to be a one, more than one more clever method by which nature learned to scream.
