Are we alone in the Universe? This is the first part of a 2-part

lecture that will explore the question of life and the Universe. We

will look at the conditions needed for life, and address the question of

how often we expect those conditions to be satisfied in our own Galaxy.

In this part, we introduce the Drake Equation and make some basic

estimates. To be honest, it was supposed to be one lecture, but I ran

over time and ran into the bell. Oops! Very embarrasing. Tomorrow's

lecture will finish up our discussion of life in the Universe, and then

wrap up Astronomy 162 for the quarter. Recorded 2006 March 9 in 1008

Evans Laboratory on the Columbus campus of The Ohio State University.