Christoph Adami makes "artificial life," effectively self-replicating computer programs. If you've heard of Tierra*, that's the kind of thing Adami does. In this TED Talk, Adami discusses his work, including a brief discussion of how we define life on Earth -- which is lots of fun, as he describes a real-world organism that does not die. And no, we haven't been overrun by this monster (yet).
After the initial discussion of "what is life" (in the context of wanting to identify extraterrestrial life),... READ ON