Technosignatures: Frameworks for Their Assessment

Abstract

In view of the promising advancements in technosignature science, the question of what constitutes a robust technosignature is rendered crucial. In this paper, we first delineate a Bayesian framework for ascertaining the reliability of potential technosignatures by availing ourselves of recent cognate research in biosignatures. We demonstrate that ideal technosignatures must not only have low risk of stemming from false positives but also evince sufficiently high prior probability of existence. Given the inherent difficulties with estimating the latter, we highlight a few alternative metrics drawn from diagnostic testing such as the Youden index that bypass the requirement of explicitly calculating the prior. We apply the models (Bayesian or otherwise) to a select few technosignature candidates and show that artificial electromagnetic signals, chlorofluorocarbons, and artifacts perform well on this front. While these results may be along expected lines, we suggest that identifying and developing suitable approaches to further evaluate technosignature candidates is of considerable importance.

Life detection in a universe of false positives

“…[30] Conversely, features such as structurally complex molecules [31] ; heredity, replication, and diversification [32] ; and technosignatures cannot exist in abiotic systems. [33] Features F I G U R E 1 Different underlying planetary processes can lead to the same atmospheric observables, which means that a specific observation of an atmosphere cannot unambiguously identify the surface processes, including biological ones. Uncertainty in the types and scale of novel chemistry, planetary processes, and biotic processes amplify this problem.…”

“…[ 30 ] Conversely, features such as structurally complex molecules [ 31 ] ; heredity, replication, and diversification [ 32 ] ; and technosignatures cannot exist in abiotic systems. [ 33 ] Features which cannot exist in abiotic systems constitute a different class of biosignatures that are not subjected to false positives because they are only associated with life in all known situations. The uncertainty associated with those features is a technical issue about detecting signals, not a conceptual issue of whether the signal is associated with the underlying processes of life.…”

Deconstructing Alien Hunting

“…In order for the programmatic search for life to survive the rollercoaster of economical resources (Garber 1999; as well as public interest; Billings 2012), it is essential that the community apply the same strict scientific standards as with any other field. Certainly efforts have already been undertaken in this direction, with Haqq-Misra & Kopparapu (2012) exploring the uncertainty in detecting alien artifacts, Catling et al (2018) outlining a Bayesian framework for biosignatures, and most recently, Lingam et al (2023) considering the Bayesian evaluation of technosignatures. Here, we seek a totally general framework for the problem of looking for life, applicable to anything from UFOs to fossils on Mars, from exoplanet biosignatures to alien relics.…”