SETI has been an active topic of research and media coverage during the recent decades. It involves looking for signals that could have been sent by an intelligent civilization as well as sending out signals to them. Effective communication with the aliens is a hard problem as they will probably have different languages for communication as we do. In this talk we will look at the various messages sent (and possibly received!) to our fellow cosmic inhabitants and the techniques proposed for effective communication with them.
From the Un-Distinguished Lecture Series (http://ws.cs.ubc.ca/~udls/). The talk was given May 11, 2007.