450104 SE Biosignatures and the "Vienna Scale" (PI) (2021S)

Unequivocal evidence for past or present life would rank among the most profound discoveries in science, and the search has been buoyed by recent exoplanet surveys have identified numerous Earth-size planets in the "habitable zones" of their stars. But for the foreseeable future, the remote detections of "biosignatures" on planets outside the Solar System is likely be of low statistical significance, ambiguous interpretation, and vulnerable to "false positives". This challenge is illustrated by controversial claims for phosphine -- one such biosignature -- in the atmosphere of Venus, the closest planet to us. With the launch of the James Webb Space Telescope, there is a need for common standards for describing the significance of any discoveries in a way analogous to the "Torino Scale" for the potential hazard by near-Earth objects. This seminar will consist of reviews of recent papers on biosignatures, online discussions with leading researchers in
the field, and participation in the writing of a "white paper"
describing a scale of certainty and unambiguity which will be henceforth known as the "Vienna scale".