It’s interesting to consider, as Hector Socas-Navarro does in a new paper, the various markers a technological civilization might leave. Searching for biosignatures is one thing — we’re developing the tools to examine the atmospheres of nearby stars for evidence of life — but how do we go about looking for astronomical evidence of a technological society, one found not by detection of a directed radio or laser beacon but by observation of the stars around us?
Various candidates have been suggested, the most famous being the Dyson sphere, in which an advanced civilization might choose to trap the energy output of its entire star, and we’re in the era of searches for such objects, as witness the Glimpsing Heat from Alien Technologies effort at Penn State. But there are many other suggestions, ranging from detecting antimatter used for power or propulsion, analyzing Fast Radio Bursts for evidence of manipulation as a propulsion system, and looking at depletion of metals in a stellar disk (asteroid mining).
Image: Astronomer Hector Socas-Navarro (Instituto de Astrofísica de Canarias). Credit: IAC.
What Socas-Navarro has in mind is a technology we have already begun to deploy and will presumably see in accelerated use. Delightfully, ...