Possibility of Interstellar Contacts Among Galactic Civilizations: An Evaluation of Solar System and Galactic Exoplanets

Known literature about the history of interstellar communication and other phases of possible contact scenarios among galactic civilizations are reviewed. The mathematical theory of spread of rumors and information developed by Dale, Kendal, Maki, Thompson, Pierce, Belen and others is used as a rough guiding principle for a possible classification of galactic civilizations, similar to Kardashev. We attempt to fill the boxes in the proposed schema by using the known and suggested properties of some of the solar system planets and known exoplanets.