|Some dare call it|
|What they don't want you to know!|
The Hollow Earth theory is a pseudoscientific belief and conspiracy theory stating that the Earth is hollow
propagated by people who's skulls are hollow. Theories include that the inhabitants of the "Inner Earth" walk around the inside feet-up,[notes 1] or that a smaller sphere is inside the larger (sometimes it is stated this object works like a sun for the inner earth denizens), which is more in line with the theory of gravity, though not geology.
The British scientist Edmond Halley[wp] (1656-1742) proposed a hollow Earth to explain anomalous compass readings. The anomalies are now known to be caused by changes in the Earth's magnetic field as well as mountains and localized iron ore deposits.
L. Sprague de Camp[wp] and Willy Otto Oskar Ley[wp] in their book Lands Beyond dubiously claimed that the scientist Leonhard Euler[wp] (1707-1783) proposed a different hollow Earth scheme, but they provided no evidence of Euler's scheme.
US Army officer John Cleves Symmes, Jr.[wp] (1780-1829) was the first known person to propose a hollow Earth with openings at both poles. He persuaded President John Quincy Adams to fund an expedition to the North Pole, but Adams left office before this could occur.
 Current pseudoscience
The conspiracy aspect supposedly relates to a large hole providing access to the underworld, which is located somewhere in the Arctic or Antarctic regions, and the attempts to keep it quiet made by the superpowers in conjunction with whatever the Grand Theory du jour is, be it reptilians, Tibetan masters, Atlanteans and/or aliens. That there are undisclosed entrances to these "inner worlds" extends also to the Moon, with one video purporting that you can see it on Google Earth, though it should be noted that this is very clearly just a graphics glitch caused by stitching multiple low-resolution and high-contrast images together in combination with the usual seam errors produced at the poles when using spherical UV mapping. These theories are also associated with apocryphal stories of apparently bottomless holes in various locations, such as Mel's Hole in Washington, USA.
It's not clear what supports the surface of the Earth according to the Hollow Earth Theory, since the surface of the earth we can see would most likely collapse under the force of gravity without a substrate (the mantle and inner core are solid, the outer core is liquid, and both states are highly resistant to compression). Nor is it clear what keeps the denizens from floating away from the inner surface.
There's also the problem that the "shell" would need to be really dense, in order to produce a gravitational field this strong.[notes 2]
Finally, there's the question of exactly why this would be kept secret — as with several other conspiracy theories, there seems to be no motive behind this one aside from "Let's make the unwashed masses look really stupid!"
 See also
- Cellular cosmogony (Earth as the inner surface of a hollow)
- Expanding Earth
- Flat Earth
- Richard Shaver
- Time Cube
- Ernst Zundel
- Hollow sun
- ↑ Gravity
is part of the conspiracydoesn't work this way; they'd be weightless.
- ↑ Gravity = Universal Gravitational constant × mass of object1 × mass of object2 over the radius squared. The average density of earth's crust is 3g/cm3 and is ~10km thick. So by their reckoning (4/3)π×radius of the earth - (4/3)π×(radius of the earth -10km) is their volume of the earth (1215778930×4π/3km3). And the mantle and core are much denser than the crust. So that number × 3×1012 kg/km3 = 1.57978336×1022 kg. Or ~.2% of earth's mass…