Ancient times In ancient times, the concept of a subterranean land inside the Earth appeared in
mythology,
folklore and
legends. The idea of subterranean realms seemed arguable, and became intertwined with the concept of "places" of origin or afterlife, such as the
Greek underworld, the
Nordic Svartálfaheimr, the Christian
Hell, and the Jewish
Sheol (with details describing inner Earth in
Kabalistic literature, such as the
Zohar and
Hesed L'Avraham). The idea of a subterranean realm is also mentioned in
Tibetan Buddhist belief. According to one story from Tibetan Buddhist tradition, there is an ancient city called
Shamballa which is located inside the Earth. In
Thracian and
Dacian legends, it is said that there are
caverns occupied by an ancient god called
Zalmoxis. In
Mesopotamian religion there is a story of a man who, after traveling through the darkness of a tunnel in the mountain of "Mashu", entered a subterranean garden. . The bell tower stands on a mound that is the site of a cave which, according to various myths, is an entrance to a place of
purgatory inside the Earth. The cave has been closed since October 25, 1632. In
Celtic mythology there is a legend of a cave called "
Cruachan", also known as "Ireland's gate to Hell", a mythical and ancient cave from which strange creatures would emerge and be seen on the surface of the Earth. There are also stories of medieval knights and saints who went on pilgrimages to a cave located in
Station Island, County Donegal in Ireland, where they made journeys inside the Earth into a place of
purgatory. In
County Down, Northern Ireland there is a myth which says tunnels lead to the land of the subterranean
Tuatha Dé Danann, a group of people who are believed to have introduced
Druidism to Ireland, and then went back underground. In
Hindu mythology, the underworld is referred to as
Patala. In the Bengali version of the Hindu epic
Ramayana, it has been depicted how
Rama and
Lakshmana were taken by the king of the underworld
Ahiravan, brother of the demon king
Ravana. Later on they were rescued by
Hanuman. The
Angami Naga tribes of
India claim that their ancestors emerged in ancient times from a subterranean land inside the Earth. The
Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground. Natives of the
Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula". Mexican folklore also tells of a cave in a mountain five miles south of
Ojinaga, and that Mexico is possessed by devilish creatures who came from inside the Earth. In the
Middle Ages, an ancient German myth held that some mountains located between
Eisenach and
Gotha hold a portal to the inner Earth. A Russian legend says the
Samoyeds, an ancient
Siberian tribe, traveled to a cavern city to live inside the Earth. The Italian writer
Dante describes a hollow earth in his well-known 14th-century work
Inferno, in which the fall of Lucifer from heaven caused an enormous funnel to appear in previously solid and spherical earth, as well as an enormous mountain opposite it, "Purgatory". In
Native American mythology, it is said that the ancestors of the
Mandan people in ancient times emerged from a subterranean land through a cave on the north side of the
Missouri River. There is also a tale about a tunnel in the
San Carlos Apache Indian Reservation in
Arizona near
Cedar Creek which is said to lead inside the Earth to a land inhabited by a mysterious tribe. It is also the belief of the
tribes of the
Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth. The elders of the
Hopi people believe that a
Sipapu entrance in the
Grand Canyon exists which leads to the
underworld.
Brazilian Indians, who live alongside the
Parima River in Brazil, claim that their forefathers emerged in ancient times from an underground land, and that many of their ancestors still remained inside the Earth. Ancestors of the
Inca supposedly came from caves which are located east of
Cuzco, Peru.
16th to 18th centuries 's hypothesis The notion was proposed by
Athanasius Kircher's non-fiction
Mundus Subterraneus (1665), which speculated that there is an "intricate system of cavities and a channel of water connecting the poles".
Edmond Halley in 1692 started with Newton's (erroneous) estimate that the density of the Moon was almost double (9/5) the density of Earth. Rather than assume a dense Moon, Halley conjectured that the Earth might consist of a hollow shell about thick, two inner concentric shells and an innermost core. Atmospheres separate these shells, and each shell has its own magnetic poles. The spheres rotate at different speeds. Halley proposed this scheme in order to explain anomalous compass readings. He envisaged the
atmosphere inside as
luminous (and possibly inhabited) and speculated that escaping gas caused the
Aurora Borealis.
Le Clerc Milfort in 1781 led a journey with hundreds of
Muscogee Peoples to a series of
caverns near the
Red River above its junction with the
Mississippi River. According to Milfort, the Muscogee Peoples believe their ancestors came out of the caverns under the surface of the Earth in ancient times. Milfort also claimed the caverns he saw "could easily contain 15,000 – 20,000 families". It is claimed that mathematician
Leonhard Euler proposed a single-shell hollow Earth with a small sun (1,000 kilometres across) at the center, providing light and warmth for an inner-Earth civilization, but that is not true. Instead, he did a thought experiment of an object dropped into a hole drilled through the center, unrelated to a hollow Earth.
19th century In 1818,
John Cleves Symmes, Jr. suggested that the Earth consisted of a hollow shell about thick, with openings about across at both
poles with 4 inner shells each open at the poles. Symmes became the most famous of the early Hollow Earth proponents, and
Hamilton, Ohio even has a monument to him and his ideas. He proposed making an expedition to the
North Pole hole, thanks to efforts of one of his followers,
James McBride.
J. N. Reynolds also delivered lectures on the "Hollow Earth" and argued for an expedition. Reynolds went on an expedition to Antarctica himself but missed joining the
Great U.S. Exploring Expedition of 1838–1842, even though that venture was a result of his agitation. Though Symmes himself never wrote a book on the subject, several authors published works discussing his ideas. McBride wrote ''Symmes' Theory of Concentric Spheres
in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: Remarks of Symmes' Theory Which Appeared in the American Quarterly Review.
In 1868, professor W.F. Lyons published The Hollow Globe'' which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Symmes's son Americus then published ''The Symmes' Theory of Concentric Spheres'' in 1878 to set the record straight.
Sir John Leslie proposed a hollow Earth in his 1829
Elements of Natural Philosophy (pp. 449–453).
William Fairfield Warren, in his book
Paradise Found – The Cradle of the Human Race at the North Pole (1885), presented his belief that humanity originated on a continent in the Arctic called
Hyperborea. This influenced some early Hollow Earth proponents. According to Marshall Gardner, both the
Eskimo and
Mongolian peoples had come from the interior of the Earth through an entrance at the
North Pole.
20th century NEQUA or The Problem of the Ages, first published in serialization in a Topeka, Kansas newspaper in 1900, is considered an early
feminist utopian novel. It mentions John Cleves Symmes' theory to explain its setting in a hollow Earth. An early 20th-century proponent of hollow Earth,
William Reed, wrote
Phantom of the Poles in 1906. He supported the idea of a hollow Earth, but without interior shells or the inner sun. The
spiritualist writer
Walburga, Lady Paget in her book
Colloquies with an unseen friend (1907) was an early writer to mention the hollow Earth hypothesis. She claimed that cities exist beneath a desert, which is where the people of
Atlantis moved. She said an entrance to the subterranean kingdom will be discovered in the 21st century. Marshall Gardner wrote ''
A Journey to the Earth's Interior in 1913 and published an expanded edition in 1920. He placed an interior sun in the Earth and built a working model of the Hollow Earth which he patented (). Gardner made no mention of Reed, but did criticize Symmes for his ideas. Around the same time, Vladimir Obruchev wrote a novel titled Plutonia'', in which the Hollow Earth possessed an inner Sun and was inhabited by prehistoric species. The interior was connected with the surface by an opening in the
Arctic. The explorer
Ferdynand Ossendowski discussed a Hollow Earth in his 1922 book titled
Beasts, Men and Gods. Ossendowski said he was told about a subterranean kingdom located inside the Earth.
Buddhists knew it as
Agharti.
George Papashvily in his
Anything Can Happen (1940) claimed when he was in the
Caucasus Mountains, he discovered a cavern containing human skeletons "with heads as big as bushel baskets" and an ancient tunnel leading to the center of the Earth. One man entered the tunnel and never returned. Novelist
Lobsang Rampa in his book
The Cave of the Ancients said an underground chamber system exists beneath the
Himalayas of
Tibet, filled with ancient machinery, records and treasure.
Michael Grumley, a
cryptozoologist, has linked
Bigfoot and other
hominid cryptids to ancient tunnel systems underground. According to the
ancient astronaut writer
Peter Kolosimo a robot was seen entering a tunnel below a
monastery in Mongolia. Kolosimo also claimed a light was seen from underground in Azerbaijan. Kolosimo and other ancient astronaut writers such as
Robert Charroux linked these activities to
UFOs. The 1964 book
The Hollow Earth by "Dr.
Raymond Bernard" presents the idea of UFOs coming from inside the Earth, states the
Ring Nebula proves the existence of hollow worlds, and speculates on the fate of
Atlantis and the origin of flying saucers. An article by
Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's
Subterranean Worlds: 100,000 Years of Dragons, Dwarfs, the Dead, Lost Races & UFOs from Inside the Earth did the connection between Bernard and Siegmeister become known to the public. The science fiction
pulp magazine Amazing Stories promoted one such idea from 1945 to 1949 as "The Shaver Mystery". The magazine's editor,
Ray Palmer, ran a series of stories by
Richard Sharpe Shaver, claiming that a superior prehistoric race had built a
honeycomb of caves in the Earth, and that their degenerate descendants, known as "Dero", live there still, using the fantastic machines abandoned by the ancient races to torment those of us living on the surface. As one characteristic of this torment, Shaver described "voices" that purportedly came from no explainable source. Thousands of readers wrote to affirm that they, too, had heard the fiendish voices from inside the Earth.
Lost Continents and the Hollow Earth (1998) by
David Hatcher Childress reprinted Palmer's stories and defended the Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia. Hollow Earth proponents have claimed a number of different locations for the entrances that lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France,
Staffordshire in England,
Montreal in Canada,
Hangzhou in China, and the
Amazon rainforest.
Variations In
A Culture of Conspiracy, political scientist
Michael Barkun draws a distinction between the terms
hollow earth and
inner earth, to differentiate materials that conceive the majority of the interior of the planet to be hollow, from those that view it as solid but
honeycombed with interconnected spaces.
Concave Hollow Earths Instead of saying that humans live on the exterior surface of a hollow planet, sometimes called a "convex" Hollow Earth hypothesis, it is hypothesized humans live on the
interior surface. This has been called the "concave" Hollow Earth hypothesis or skycentrism.
Cyrus Teed, a doctor from upstate New York, proposed such a concave Hollow Earth in 1869, calling his scheme "Cellular Cosmogony". Teed founded a group called the
Koreshan Unity based on this notion, which he called
Koreshanity. The main colony survives as a preserved Florida state historic site, at
Estero, Florida, but all of Teed's followers have now died. Teed's followers claimed to have experimentally verified the concavity of the Earth's curvature, through surveys of the Florida coastline making use of "rectilineator" equipment. Several 20th-century German writers, including
Peter Bender, Johannes Lang, Karl Neupert, and Fritz Braut, published works advocating the Hollow Earth hypothesis, or
Hohlweltlehre. Some members of
Adolf Hitler's naval staff were influenced by concave Hollow Earth ideas and sent an expedition in an unsuccessful attempt to spy on the British fleet by pointing infrared cameras up at the sky. The
Egyptian mathematician
Mostafa Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model. In his book
On the Wild Side (1992),
Martin Gardner discusses the Hollow Earth model articulated by Abdelkader. According to Gardner, this hypothesis posits that light rays travel in circular paths, and slow as they approach the center of the spherical star-filled cavern. No energy can reach the center of the cavern. A drill, Gardner says, would lengthen as it traveled away from the cavern and eventually pass through the "point at infinity" corresponding to the center of the Earth. Gardner notes that "most mathematicians believe that an inside-out universe, with properly adjusted physical laws, is empirically irrefutable". Gardner rejects the concave Hollow Earth hypothesis on the basis of
Occam's razor. Purportedly verifiable hypotheses of a Concave Hollow Earth need to be distinguished from a thought experiment which defines a
coordinate transformation such that the interior of the Earth becomes "exterior" and the exterior becomes "interior". (For example, in spherical coordinates, let radius
r go to
R2/
r where
R is the Earth's radius; see
inversive geometry.) The transformation entails corresponding changes to the forms of physical laws. This is not a hypothesis but an illustration of the fact that any description of the physical world can be equivalently expressed in more than one way. == Contrary evidence ==