Luminiferous aether

Obsolete postulated medium for the propagation of light

Luminiferous aether or ether (luminiferous meaning 'light-bearing') is the formerly postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space (a vacuum), something that waves should not be able to do. The assumption of a spatial plenum (space completely filled with matter) of luminiferous aether, rather than a spatial vacuum, provided the theoretical medium that was required by wave theories of light.

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