Lecture 43: Extraterrestrial Life

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.