  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.
