SETI Before Marconi: Sunlight Beacons and the Fermi Paradox

S. Baxter (2008), JBIS, 61, 440-443

Refcode: 2008.61.440
Keywords: SETI, search for extraterrestrial intelligence, beacons, optical SETI, Fermi paradox.

Abstract:
The strategies underlying the search for extraterrestrial intelligence are generally predicated on a model of civilisations with telecommunications technology searching for evidence of each other and making contact accordingly. It is argued that there is at least one plausible signalling type detectable to pre-radio civilisations: naked-eye `sunlight beacons’. A motive for attempting such communication could be the remote detection of the injection of greenhouse and other waste gases into a planetary atmosphere as a result of agricultural and early industrial activities. We may have been detectable, and contactable, since the Neolithic. An absence of such contacts is therefore a deepening of the Fermi Paradox.