Technosignatures longevity and Lindy's law

TL;DR

This paper explores how Lindy's law influences the expected longevity of technosignatures and the implications for their detectability and inferred age, challenging the assumption that the first detected technosignature is necessarily very long-lived.

Contribution

It introduces Lindy's law as a model for technosignature longevity and analyzes its impact on detection probabilities and the inferred age of technosignatures.

Findings

Lindy's law can alter expectations about the longevity of technosignatures.

The first detected technosignature may not be the longest-lived.

Estimations of the number of emitters needed for detection are discussed.

Abstract

The probability of detecting technosignatures (i.e. evidence of technological activity beyond Earth) increases with their longevity, or the time interval over which they manifest. Therefore, the assumed distribution of longevities has some bearing on the chances of success of technosignature searches, as well as on the inferred age of technosignatures following a first contact. Here, we investigate the possibility that the longevity of technosignatures conforms to the so-called Lindy's law, whereby, at any time, their remaining life expectancy is roughly proportional to their age. We show that, if Lindy's law applies, the general tenet that the first detected technosignature ought to be very long lived may be overruled. We conclude by discussing the number of emitters that had to appear, over the history of the Galaxy, in order for one of them to be detectable today from Earth.