Strange Attractor

What is the atmosphere? Atmosphere of Earth (Wikipedia) (https://en.wikipedia.org/wiki/Atmosphere_of_Earth) Evolution of Earth's atmosphere (Wikipedia) (https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Evolution_of_Earth.27s_atmosphere) Earth's early atmosphere (Universe Today) (https://www.universetoday.com/26659/earths-early-atmosphere/) A lecture on Earth's atmosphere (The Ohio State University) (http://www.astronomy.ohio-state.edu/~pogge/Ast141/Unit3/Lect10_Atmos.pdf) Gaseous composition of dry air (Columbia University) (http://eesc.columbia.edu/courses/ees/slides/climate/table_1.html) Not definitive, but a discussion around 'How is the equilibrium of 21% oxygen in Earth's atmosphere established?' (Earth Science Stack Exchange) (https://earthscience.stackexchange.com/questions/4574/how-is-the-equilibrium-of-21-oxygen-in-earths-atmosphere-established) The first cells were anaerobic, i.e. they didn't use oxygen (Windows 2 Universe) (http://www.windows2universe.org/earth/Life/first_life.html) The great oxyg