The seminar will be streamed here.
Abstract:
It is often claimed that astrobiologists need a definition of life in order to search for extraterrestrial life: How else can one recognize alien life if one is fortunate enough to encounter it? Yet, as I briefly discuss, definitional approaches face serious logical problems. This talk explores an alternative strategy for searching for extraterrestrial life: Search for potentially biological anomalies (as opposed to life per se) using tentative (vs. defining) criteria. The function of tentative criteria is not, like that of defining criteria, to decide the question of life. Instead, it is to identify phenomena that are especially difficult to classify as living or nonliving as worthy of further scientific investigation for the possibility of novel life. While the proposed strategy resembles that of current life-detection missions, insofar as it advocates the use of a variety of lines of evidence (biosignatures), it differs from these approaches (including so-called “agnostic” biosignatures) in ways that increase the likelihood of noticing truly novel forms of life, as opposed to dismissing them as just another poorly understood abiotic phenomenon. Last but not least, the strategy under consideration would be just as effective at detecting forms of life closely resembling our own as a definition of life.