Hollow Earth Theory

Record	OBS-0014
Category	Unexplained/Hidden Earth
Status	DEBUNKED
Summary	The Hollow Earth theory proposes that the Earth is hollow or contains vast interior spaces, often with entrances at the poles. Proponents have suggested that inner spheres or a habitable interior exist, sometimes inhabited by advanced civilizations or UFOs. The theory was notably advocated by Edmond Halley in the 17th century and John Cleves Symmes Jr. in the 19th century.
Origin	The concept has ancient mythological roots, but the scientific hypothesis was proposed by Edmond Halley in 1681 to explain magnetic compass variations. It gained popularity in the 19th century through John Cleves Symmes Jr., who advocated for polar openings.
Claimed	The Earth is hollow, consisting of concentric shells or a large interior space. There are openings at the North and South Poles, sometimes called 'Symmes' Hole', that lead to the interior. The interior may contain habitable regions, lost civilizations, or even flying saucers. Compass variations are caused by the movement of inner spheres or magnetic rims around polar openings.
Evidence / consensus	The theory has been disproven by geophysical evidence. The Earth has a solid crust, mantle, and core, with no hollow spaces. The Schiehallion experiment in 1774 measured the density of the Earth and confirmed it is solid. Seismic studies and gravity measurements further refute any large interior voids.

> OBSERVER NOTE:
A classic pseudoscientific hypothesis, now thoroughly refuted by geophysics. Its persistence in fringe circles is notable, often merging with UFO lore and polar exploration myths.

Sources

Sources are external and provided for verification. Listing does not imply the Observer endorses their claims.