A theory first propounded by Werner Milesius, a fringe Meteoromancer, which holds that what is commonly referred to as "thin air" is not, in fact, thin, but is filled with a heavy fluid that blankets the earth and extends upward into the sky, pervading all things. Thus, ships rise not for the obvious reason that they have negative weight (an explanation which Milesius characteristically dismissed as "uncompelling"), but because they are actually floating on air, just as a log floats on water.

Milesius saw the Aether Hypothesis as the basis of all true knowledge (for instance, he believed that sound waves, and possibly even light, consisted of vibrations in the air-fluid), and attempted to found a school to reinterpret all past Meteoromancy in light of his discovery, but his methods never gained popularity, and eventually his research became mired in politics when his unorthodox views were condemned by the Oversight Committee. Milesius himself retired in obscurity after repeated failures to produce gold out of thin air. Although never widely accepted by the scientific community, his Hypothesis forms the theoretical basis for the Convection Engine used by Cid Highwind in his famous flight.

—Iohannes Edgardus Quobertius