The Universe’s Habitable Zone

Humans have a severe case of societal loneliness.  We send signals out into the void in the hopes that someone might answer, we launch spacecraft into the interstellar medium with a record of our civilization, we push the edges of our technology to seek evidence of long-extinct microbial and unicellular life on the Moon, Mars, asteroids, and other bodies in our solar system.  On a less evidential level, we seek clues, stories, and anecdotes that could enable us to believe that our species is not alone in the universe: points of light in the sky, a circle painted on a cave wall ten thousand years ago, unexplained happenings all over the world.

Sententia Discussion Series 3: Habitability

The search for extra-terrestrial life tends to focus on the requirements for life on Earth: carbon, oxygen, liquid water, and so forth. There are arguments that support the idea that any life would have similar needs. Yet there are also arguments that life could be so alien that we might not even recognize it as life. Indeed, the biological definition of life can be interpreted to include things like stars, which are generally not considered "alive."