The theory that, as the node title suggests, our
Earth is hollow inside.
The Origins of the Hollow Earth Theory
The idea was first thought up by the English astronomer Edmund Halley in 1692. He noticed that the direction of the Earth's magnetic field varied slightly over time. To explain this variation he thought up the idea that inside Earth are four shells or spheres, of 800 mile thickness, each with a different magnetic field. He believed that there was a luminous atmosphere in the centre of these spheres, and that this gas supported some form of unspoilt, paradisiac life. He also thought that the Earth's crust was thinner at the poles, allowing some of this central light to escape & cause the aurora borealis, or Northern Lights, to appear.
Earth as a Big Egg
The Hollow Earth theory was later developed by the Swiss mathematician Leonhard Euler, who thought that Earth was structured like a giant egg, with a thin shell and a sunny inside. He believed that the earth was a single sphere that contained a sun measuring 600 miles in diameter. This sun served to provide heat and light for the unhatched chick - an underground population of "advanced" life forms. (if this was the case, surely the egg must have come first..)
Another mathematician, Sir John Leslie, put forward a similar idea at around the same time: that Earth contains two suns, namely Pluto and Proserpine.
The idea of energy from the centre of the earth ("vril") is explored in Bulwer-Lytton's science-fiction novel The Coming Age. (thanks to JudyT for this info.)
The Holes at the Poles
The American John Symmes was a strong supporter of Halley's theory, and spent most of his later life trying to prove the existence of the earth's shells. An ex-army officer and businessman, he was able to convince the U.S. government in 1938 to send out an expedition team, whose mission it was to discover and explore the 4000 mile wide hole at the North Pole. Symmes was convinced that this hole was one of two entrances to the inner earth. They found no evidence.
Inner Earth - the Promised Land
Another Hollow Earth fanatic was Cyrus Read Teed. He elaborated upon the theory and by the 1900s had turned it into a cult. Changing his name to Koresh, he proclaimed himself the messiah of a new religion whose goal it was to seek out the civilisation hiding under the Earth's crust. They would prove that a sun rotated in the centre of the planet, casting half of the inner world into darkness, and that a people wandered around inside the sphere, their vision clouded by a thick atmosphere and their lives governed by the rising and setting of the sun. Mr. Koresh died in 1908, having proved none of his wondrous ideas.
The Nazis: an alien race from Inner Earth?
After the Second World War, more stories sprouted from the Hollow Earth theory; this time about Nazi hideouts. It was said by Ernst Zündel, author of UFOs - Nazi Secret Weapons?, that the Nazis were an inner-earth race who had emerged from the entrances at the poles, and returned in submarines and flying saucers after a brief stop in Argentina at the end of the war. There was also a tale that Hitler sent an expedition during WWII to a Baltic Island, where a telescopic camera was pointed into the sky in order to photograph the British across the hollow, concave interior of the Earth. It failed.
Support for the Hollow Earth Theory
Many have attempted to prove or disprove this theory since it was first borne...
- Marshall Gardner suggested that the a frozen mammoth discovered in Siberia in 1849 was so well preserved because it had died recently, having come from the inner earth.
- A NASA photograph showing a small black hole at the North Pole was seized by an enthusiast, but this was dismissed. The picture was composed of photographs taken over a 24 hour period and layered together, and the black spot was the area of the Arctic Circle, which is never in daylight during winter. No other photographs taken in space have shown any sign of holes or entrances into the earth.
- Admiral Richard Byrd of the U.S. Navy flew over both the North and South poles but saw no evidence of holes leading into the earth.
- Geological methods such as seismology strongly indicate that the earth is indeed mainly solid.
There are, however, some discoveries that have been called up as weak support.
- A recent search in Romania has uncovered an underground ecosystem in which spiders, scorpions, leeches and other such creatures are included. Other caves have been found supporting rock-eating bacteria, proving the possibility of life forms that do not need light as an energy source.
- Rock from Mars has been found in the antarctic with evidence that bacteria may (have) live(d) underground on the planet.
- Teed's rotating sun idea cannot be disproved, as the exterior of a sphere can easily be mapped onto its interior.
Another suggestion is that there are a number of passageways leading down to the caverns in the centre of the earth. This idea is explored in Jules Verne's popular book Journey to the Center of the Earth, in which a group of scientists find an underground sea inhabiting plesiosaurs beneath an inactive volcano1. This, however, is purely fiction. As most people agree, the idea of a Hollow Earth is becoming increasingly more like science-fiction than plausible theory worth investigating.
1 liveforever says There is reason to believe that Verne was inspired by the earlier success of Danish Ludvig Holberg's story of Niels Klim (Niels Klim's Subterranean Journey), who travelled to a hollow earth.
http://www.unmuseum.org/hollow.htm
http://www.gi.alaska.edu/ScienceForum/ASF7/718.html