Carl Sagan was a popular scientist, skeptic, astronomer, and media personality. He is perhaps best known for the PBS television series, Cosmos. Sagan saw no reason to believe in a personal God or anything beyond physical reality and the laws that govern the universe though he did not consider himself an atheist because he could not disprove god.
Sagan feared the reason why humans have not found evidence for extraterrestrial civilizations could be that technoligically advanced extraterrestrial communities destroyed themselves. He was concerned that humanity should not destroy itself.
Sagan was founder of The Planetary Society.
- The Dragons of Eden: Speculations on the Evolution of Human Intelligence ISBN 0-345-34629-7
- Broca's Brain: Reflections on the Romance of Science, ISBN 0-345-33689-5
- Cosmos, ISBN 0-375-50832-5
- The Demon-Haunted World: Science as a Candle in the Dark, ISBN 0-345-40946-9