Clinamen
Clinamen is the word Lucretius gave to the unpredictable swerve of atoms. He means that these atoms don't just fall down, but because of the swerve collisions happen.[1] Lucretius wrote that without this slight swerve (atoms) would "fall like raindrops and never touch and the world would have never been made".[1] Lucretius was the first to write about Chaos theory.[2]
