Reaction to Bracewell (1960)

This paper describes a new search method and suggests a Schelling point for contacting extraterrestrial civilizations through detection of their emissaries in our solar system. Bracewell discusses the difficulty with maintaining an array of radio transmitters beaming signals to all nearby star systems in the style of Cocconi & Morrison (1959). The method for handling this problem is primarily thought-based.  Bracewell argues that it would be more feasible to send probes to each system and wait for the emergence of a radio-capable technology in that system before relaying such information back to the advanced civilization. They further argue that due to the difficulties with sending macroscopic objects across interstellar distances, it would be worthwhile to outfit such a probe with advanced communicative and computational capabilities. This paper is novel for the suggestion that such “Bracewell” probes may exist and that it may be in our interest to search for evidence of them in our own solar system. He concludes that a null detection of such a probe would constitute evidence that either such probes are unfeasible or that the superior community is at such a distance that the possibility of successful contact with us is low. They admit the possibility of longer-lived, sustained civilizations which have bypassed the low mean lifespan they determine from their probability experiment. If we limit the search for Bracewell probes to simply searching for an object in the solar system with radio emission, it may be possible at some point in time to deem the search complete. However, advanced civilizations may have access to technologies which are unknown or undetectable to us, which would make their detection impossible to our instruments, thereby leading to an un-ending search with no definitive conclusion. Therefore, even in our modernity we cannot dislodge the primary idea of this paper. The obvious follow up to this paper would be targeted observational searches for the aforementioned radio emissions emerging anomalously and unnaturally within our own solar system. A Herculean project for the future would be a surface mapping of the majority of macroscopic objects in orbit around the Sun at high resolution and then employing machine-learning algorithms to hunt for sedentary, exposed Bracewell probes of perfect geometric dimension.