Editing Anaximander (section)

=== A free-floating Earth ===

Anaximander was the first to conceive a mechanical model of the world. In his model, the Earth floats very still in the centre of the infinite, not supported by anything. It remains "in the same place because of its indifference", a point of view that Aristotle considered ingenious, in ''[[On the Heavens]]''.<ref>Aristotle, ''On the Heavens'', ii, 13</ref> Its curious shape is that of a cylinder<ref>"A column of stone", [[Aëtius (theologian)|Aetius]] reports in ''De Fide'' (III, 7, 1), or "similar to a pillar-shaped stone", pseudo-Plutarch (III, 10).</ref> with a height one-third of its diameter. The flat top forms the inhabited world.

[[Carlo Rovelli]] suggests that Anaximander took the idea of the Earth's shape as a floating disk from [[Thales of Miletus|Thales]], who had imagined the Earth floating in water, the "immense ocean from which everything is born and upon which the Earth floats."{{sfn|Rovelli|2023|p=48}} Anaximander was then able to envisage the Earth at the centre of an infinite space, in which case it required no support as there was nowhere "down" to fall. In Rovelli's view, the shape – a cylinder or a sphere – is unimportant compared to the appreciation of a "finite body that floats free in space."{{sfn|Rovelli|2023|p=48}}

[[File:Floating Earth Thales Anaximander.svg|thumb|upright=1.75|center|Whereas [[Thales of Miletus|Thales]] thought the Earth floated in the great Ocean, Anaximander saw the Earth as floating in the infinite. Where Thales conceived of things falling down to Earth, and Earth being above the Ocean, Anaximander saw the Earth as the centre, and that things could fall from any direction. This has been thought a large conceptual advance in cosmology.{{sfn|Rovelli|2023|pp=48–52}}]]

Anaximander's realization that the Earth floats free without falling and does not need to be resting on something has been indicated by many as the first cosmological revolution and the starting point of scientific thinking.{{sfn|Rovelli|2023|pp=49–50}} [[Karl Popper]] calls this idea "one of the boldest, most revolutionary, and most portentous ideas in the whole history of human thinking."<ref>Karl Popper, "Conjectures and Refutations: The Growth of Scientific Knowledge" (New York: Routledge, 1998), p. 186.</ref> Such a model allowed the concept that [[Astronomical object|celestial bodies]] could pass under the Earth, opening the way to Greek astronomy. Rovelli suggests that seeing the stars circling the [[Pole star]], and both vanishing below the horizon on one side and reappearing above it on the other, would suggest to the astronomer that there was a void both above and below the Earth.{{sfn|Rovelli|2023|pp=50–52}}

[[File:Starry Spin-up.jpg|thumb|upright=1.75|center|The sight of stars circling the [[Pole star]] and vanishing and reappearing at the horizon could have suggested to Anaximander that the Earth was surrounded above and below by a void.{{sfn|Rovelli|2023|pp=50–52}}]]