Lecture 43: Extraterrestrial Life Astronomy 141 - Life in the Universe

What does extraterrestrial life look like? This lecture explores
current thinking about what extraterrestrial life might be like not by
guessing their appearances, but instead applying lessons learned from
our growing understanding of how evolution and biochemistry work on
Earth. I will discuss Universal versus Parochial characteristics,
Convergent Evolution, Radical Diversity, and other ideas from
evolutionary biology that might inform how life might emerge on other
worlds. We will then look at alternatives to carbon biochemistry,
specifically the possibility of silicon-based life, and alternatives to
liquid water as a solvent medium for biochemistry, specifically the
possible role of Ammonia. Finally I will give one example of a highly
speculative idea about life without chemistry. In the end, the outcome
of such studies may not be to tell us much about extraterrestrials as to
help focus questions on how we ourselves arose. Recorded live on 2009
Dec 1 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio
State University.