Stages of galactic history with respect to extraterrestrial intelligence : note

In this document, Carl Sagan imagines the history of the galaxy with respect to extraterrestrial intelligence. He mentions the first generation of stars, the formation of planets, the evolution of stars, the development of radio telescopes to establish contact between various technical civilizations and a time in the future when the galaxy has been crisscrossed by intelligence many times. From Carl Sagan's "ideas riding" files, a play on "ideas writing." These files contain a running set of initial concepts for various writing projects. This note was cross-filed with Sagan's notes on his novel Contact.