Chapter 7: The Backbone of Night

Chapter VII of Cosmos begins by tracking the evolution of human cosmological understanding, contrasting the author's personal childhood quest to identify the stars with the way ancient cultures sought explanations for unknown phenomena, often attributing them to capricious, unseen causes or deities, as Baron von Holbach noted. Early hunter-gatherer societies developed imaginative, competing metaphors for the night sky, such as stars being distant campfires or holes in a dark animal skin, while the !Kung Bushmen developed the elegant concept of the Milky Way as "the backbone of night." This reliance on unpredictable gods was challenged around 600 B.C. by the Ionian Awakening, a pivotal intellectual revolution originating in the eastern Aegean Sea. This movement established the notion of Cosmos, asserting that the universe is orderly, governed by knowable natural laws, and therefore comprehensible, moving away from the preceding concept of Chaos. Ionia’s location at the crossroads of civilizations and its politically diverse climate fostered free inquiry. Key Ionian pioneers, often combining theoretical speculation with practical skills, included Thales of Miletus, who explained natural occurrences without divine intervention; Anaximander, an early evolutionist who proposed that the Earth was suspended unsupported in space; and Empedocles, who conducted the first recorded experiment on air using a clepsydra (water thief) to demonstrate that the invisible substance was material and exerted pressure. Most significantly, Democritus proposed the existence of atoms (Greek for "unable to be cut") as the ultimate constituents of the world, a concept he paired with the idea of the void, and his work even approached modern calculus. However, the Ionian tradition of observation was suppressed by the philosophical school of Pythagoras, which valued mathematical deduction and mysticism over experiment, a trend reinforced by Plato and Aristotle’s disdain for manual labor, often linked to the pervasive slave economy of the era. Despite this setback, the astronomer Aristarchus of Samos first advanced the heliocentric hypothesis, correctly placing the Sun, rather than the Earth, at the center of the solar system, though this truth was forgotten for 1,800 years. Later telescopic observations and geometry, particularly the work of Harlow Shapley in the twentieth century, further cemented the concept that neither humanity nor our planet holds a privileged place in the Cosmos, demonstrating that the solar system is located far on the outskirts of the Milky Way, which, as Edwin Hubble later proved, is merely one of billions of island universes in the vast expanse.