NPM Errors should not _just_ have process exited with status code 1

[bryanmacfarlane]

Errors from npm should ideally be highlighted and / or become a problem matcher

[thomas-schuster]

Is there a possibility to access the error log if an actions workflow is executed on GitHub environment?

[Jamawre]

This article is about the concept. For other uses, see Hollow Earth (disambiguation).

A cross-sectional drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel
The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproved, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.

It was still occasionally defended through the mid-19th century, notably by John Cleves Symmes Jr. and Jeremiah N. Reynolds, but by this time it was part of popular pseudoscience and no longer a scientifically viable hypothesis.
This article is about the concept. For other uses, see Hollow Earth (disambiguation).

A cross-sectional drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel
The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproved, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.

It was still occasionally defended through the mid-19th century, notably by John Cleves Symmes Jr. and Jeremiah N. Reynolds, but by this time it was part of popular pseudoscience and no longer a scientifically viable hypothesis.

The concept of a hollow Earth still recurs in folklore and as a premise for subterranean fiction, a subgenre of adventure fiction.

Contents
1 Hypothesis
1.1 16th to 18th centuries
1.2 19th century
1.3 20th century
1.4 Concave Hollow Earths
2 Schiehallion experiment
3 Contrary evidence
3.1 Seismic
3.2 Gravity
3.3 Direct observation
4 In fiction
5 In popular art
6 See also
7 References
8 Bibliography
9 External links
Hypothesis
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.[1][2] According to one story from Tibetan Buddhist tradition, there is an ancient city called Shamballa which is located inside the Earth.[2]

According to the Ancient Greeks, there were caverns under the surface which were entrances leading to the underworld, some of which were the caverns at Tainaron in Lakonia, at Troezen in Argolis, at Ephya in Thesprotia, at Herakleia in Pontos, and in Ermioni.[3] In Thracian and Dacian legends, it is said that there are caverns occupied by an ancient god called Zalmoxis.[4] 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.[5]

Chapel, bell tower and penitential beds on Station Island. 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 according to legend strange creatures would emerge and be seen on the surface of the Earth.[6] 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.[7] 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.[8]

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.[9] The Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground.[10]

Natives of the Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula".[11] 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.[12]

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.[13] The Italian writer Dante describes a hollow earth in his well-known 14th-century work , in which the fall of Lucifer from heaven caused an enormous funnel to appear in a 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 at the north side of the Missouri River.[14] 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.[15] It is also the belief of the tribes of the Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth.[16] The elders of the Hopi people believe that a Sipapu entrance in the Grand Canyon exists which leads to the underworld.[17][18]

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.[19]

16th to 18th centuries

Edmond Halley's hypothesis
The following lines from Act 3, Scene 2 of Shakespeare's play , written in London in 1595/6, suggest that the idea may have been known in Western Europe 100 years before it took on a more scientific form: Hermia: 'I'll believe as soon / This whole earth may be bored and that the moon / May through the center creep and so displease / Her brother's noontide with Antipodes.'

The notion was further popularized by Athanasius Kircher's non-fiction (1665), who speculated that there is an "intricate system of cavities and a channel of water connecting the poles".[20]: 137 

Edmond Halley in 1692[21] conjectured that the Earth might consist of a hollow shell about 800 km (500 mi) 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.[22]

Le Clerc Milfort in 1781 led a journey with hundreds of Creek Indians to a series of caverns near the Red River above the junction of the Mississippi River. According to Milfort the original Creek Indian ancestors are believed to have emerged out to the surface of the Earth in ancient times from the caverns. Milfort also claimed the caverns they saw "could easily contain 15,000 – 20,000 families."[23][24]

It is often claimed that mathematician Leonhard Euler proposed a single-shell hollow Earth with a small sun (1.000 kilometres across) at the centre, providing light and warmth for an inner-Earth civilisation, but that is not true. He did a thought experiment of an object dropped at a hole drilled trough the centre.[25]

19th century
In 1818, John Cleves Symmes, Jr. suggested that the Earth consisted of a hollow shell about 1,300 km (810 mi) thick, with openings about 2,300 km (1,400 mi) 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.[26] He proposed making an expedition to the North Pole hole,[27] thanks to efforts of one of his followers, James McBride.

Jeremiah 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 about his ideas, several authors published works discussing his ideas. McBride wrote in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: In 1868, a professor W.F. Lyons published which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Symmes's son Americus then published in 1878 to set the record straight.

Sir John Leslie proposed a hollow Earth in his 1829 (pp. 449–53).

In 1864, in [28] Jules Verne describes a hollow Earth containing two rotating binary stars, named Pluto and Proserpine.

William Fairfield Warren, in his book (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.[29]

20th century
, first serialized in a newspaper printed in Topeka, Kansas in 1900 and considered an early feminist utopian novel, mentions John Cleves Symmes' theory to explain its setting in a hollow Earth.

An early 20th-century proponent of hollow Earth, William Reed, wrote in 1906. He supported the idea of a hollow Earth, but without interior shells or inner sun.

The spiritualist writer Walburga, Lady Paget in her book (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.[30]

Marshall Gardner wrote 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 (U.S. Patent 1,096,102). Gardner made no mention of Reed, but did criticize Symmes for his ideas. Around the same time, Vladimir Obruchev wrote a novel titled , 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 wrote a book in 1922 titled . Ossendowski said he was told about a subterranean kingdom that exists inside the Earth. It was known to Buddhists as Agharti.[31]

George Papashvily in his (1940) claimed the discovery in the Caucasus mountains of 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.[32]

Novelist Lobsang Rampa in his book said an underground chamber system exists beneath the Himalayas of Tibet, filled with ancient machinery, records and treasure.[33] Michael Grumley, a cryptozoologist, has linked Bigfoot and other hominid cryptids to ancient tunnel systems underground.[34]

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.[35] Kolosimo and other ancient astronaut writers such as Robert Charroux linked these activities to UFOs.

A book by a "Dr. Raymond Bernard" which appeared in 1964, , exemplifies the idea of UFOs coming from inside the Earth, and adds the idea that the Ring Nebula proves the existence of hollow worlds, as well as speculation on the fate of Atlantis and the origin of flying saucers.[36][37] An article by Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's did the full story of Bernard/Siegmeister become well-known.[38]

The science fiction pulp magazine 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 pre-historic 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. The writer David Hatcher Childress authored (1998) in which he reprinted the stories of Palmer and defended the Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia.[39]

Hollow Earth proponents have claimed a number of different locations for the entrances which lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France,[40] Staffordshire in England,[41] Montreal in Canada,[42] Hangchow in China,[43] and the Amazon Rainforest.[44]

Concave Hollow Earths

An example of a concave hollow Earth. Humans live on the interior, with the universe in the center
Instead of saying that humans live on the outside surface of a hollow planet—sometimes called a "convex" Hollow Earth hypothesis—some have claimed humans live on the surface of a hollow spherical world, so that our universe itself lies in that world's interior. 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".[45] 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 . It has even been reported, although apparently without historical documentation, that Adolf Hitler was 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.[46][47]

The Egyptian mathematician Mostafa Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model.[48][49]

In one chapter of his book (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, which corresponds to no point a finite distance away from Earth in the widely accepted scientific cosmology. 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 in the widely accepted scientific cosmology. Supposedly no experiment can distinguish between the two cosmologies.

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.[50]

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 go to 2/ where 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.[51]

Schiehallion experiment
Main article: Schiehallion experiment
In 1735, Pierre Bouguer and Charles Marie de La Condamine chartered an expedition from France to the Chimborazo volcano in Ecuador. Arriving and climbing the volcano in 1738, they conducted a vertical deflection experiment at two different altitudes to determine how local mass anomalies affected gravitational pull. In a paper Bouguer wrote a little over ten years later, Bouguer commented that his results had at least falsified the Hollow Earth Theory. In 1772, Nevil Maskelyne proposed to repeat the same experiment to the Royal Society. Within the same year, the Committee of Attraction was formed and they sent Charles Mason to find the perfect candidate for the vertical deflection experiment. Mason found the Schiehallion mountain, where the experiment took place and not only supported the earlier Chimborazo Experiment but yielded far greater results.

Contrary evidence
Seismic
The picture of the structure of the Earth that has been arrived at through the study of seismic waves[52] is quite different from a fully hollow Earth. The time it takes for seismic waves to travel through and around the Earth directly contradicts a fully hollow sphere. The evidence indicates the Earth is mostly filled with solid rock (mantle and crust), liquid nickel-iron alloy (outer core), and solid nickel-iron (inner core).[53]

Gravity
Main articles: Schiehallion experiment and Cavendish experiment
Another set of scientific arguments against a Hollow Earth or any hollow planet comes from gravity. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid spheroid is the best way in which to minimize the gravitational potential energy of a rotating physical object; having hollowness is unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve hydrostatic equilibrium with its own mass and would collapse.

Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm3, and typical densities of surface rocks are only half that (about 2.75 g/cm3). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13 g/cm3, which brings the average density of Earth to its observed value.

Direct observation
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the Kola Superdeep Borehole,[54] with a true vertical drill-depth of more than 7.5 miles (12 kilometers). However, the distance to the center of the Earth is nearly 4,000 miles (6,400 kilometers). Oil wells with longer depths are not vertical wells; the total depths quoted are measured depth (MD) or equivalently, along-hole depth (AHD) as these wells are deviated to horizontal. Their true vertical depth (TVD) is typically less than 2.5 miles (4 kilometers).

In fiction
Main article: Subterranean fiction
The idea of a hollow Earth is a common element of fiction, appearing as early as Ludvig Holberg's 1741 novel (Niels Klim's Underground Travels), in which Nicolai Klim falls through a cave while spelunking and spends several years living on a smaller globe both within and the inside of the outer shell.

Other notable early examples include Giacomo Casanova's 1788 , a 5-volume, 1,800-page story of a brother and sister who fall into the Earth and discover the subterranean utopia of the Mégamicres, a race of multicolored, hermaphroditic dwarves; published anonymously in 1819; by a "Captain Adam Seaborn" (1820) which reflected the ideas of John Cleves Symmes, Jr.; Edgar Allan Poe's 1838 novel Jules Verne's 1864 novel which showed a subterranean world teeming with prehistoric life; George Sand's 1864 novel where giant crystals could be found in the interior of the Earth; , an 1895 science-fiction allegory with major subterranean themes; and , a 1908 novel that included the idea that the North Pole was the entrance to the hollow planet.

In William Henry Hudson's 1887 romance, , the protagonist falls down a hill into a Utopian paradise; since he falls into this world, it is sometimes classified as a hollow Earth story; although the hero himself thinks he may have traveled forward in time by millennia.

The idea was used by Edgar Rice Burroughs in the seven-novel "Pellucidar" series, beginning with (1914). Using a mechanical drill, called the Iron Mole, his heroes David Innes and Professor Abner Perry discover a prehistoric world called Pellucidar, 500 miles below the surface, that is lit by a constant noonday inner sun. They find prehistoric people, dinosaurs, prehistoric mammals and the Mahar, who evolved from pterosaurs. The series ran for six more books, ending with (1963).[55] The 1915 novel by Vladimir Obruchev uses the concept of the Hollow Earth to take the reader through various geological epochs.

In recent decades, the idea has become a staple of the science fiction and adventure genres across films ( and the MonsterVerse), television programs (the third and fourth seasons of ), role-playing games (e.g., the Hollow World Campaign Set for , ), and video games ( and ).

In popular art
In 1975 Japanese artist Tadanori Yokoo used elements of the Aghartha legend, along with other Eastern subterranean myths, to depict an advanced civilization in the cover art for jazz musician Miles Davis's album .[56] Tadanori said he was partly inspired by his reading of Raymond W. Bernard's 1969 book .[57]

See also
Brinsley Le Poer Trench, 8th Earl of Clancarty - 1974 proponent of Hollow Earth
Dyson sphere
Expanding Earth
Flat Earth
Hades
Hollow Moon
List of topics characterized as pseudoscience
Scientific skepticism
Shamballa
Shellworld
Travel to the Earth's center
Xibalba
References
Hollow Earth in the Puranas Online
The Way to Shambhala, Edwin Bernbaum, Anchor Books; 1st edition, 1980 ISBN 0-385-12794-4
Sherwood Fox, William (1916), , 1, Boston, Marshall Jones Company, p. 143
Mircea Eliade, Zalmoxis, the vanishing God: comparative studies in the religions and folklore of Dacia and Eastern Europe, 1959, pp. 24–30
Myth: its meaning and functions in ancient and other cultures, G. S. Kirk, 1970, p. 136
John A MacCulloch, Celtic Mythology, Rowman & Littlefield Pub Inc, 1932, pp. 125–26
T. Write, Saint Patrick's Purgatory : A medieval Pilgrimage in Ireland, 1918, p. 107
Harold Bayley, Archaic England: An Essay in Deciphering Prehistory from Megalithic Monuments, 1919 Online Edition: Link
Angami NagaBrown, Account of Munnipore, 1968., p. 113
Ellen Russell Emerson, Indian Myths, 1965 "It is to the Cubans we are indebted for the following version of man's origin: It was from the depths of a deep cavern in the earth that mankind issued."
Philip Freund, Myths of Creation; 1965, pp. 131–32
George, Wally – Pilgrimage To The Devil., Article in Fate magazine, Aug. 1957, pp. 38–52
Clark B Firestone and Ruth Hambidge, The Coasts of Ilusion, Harper & Bros; First Edition, 1924
Martha Warren Beckwith, Mandan-Hidatsa myths and ceremonies, G. E. Stechert, 1937, p. 10
Grenville Goodwin, Myths and Tales of the White Mountain Apache, 1939, p. 20 (Kessinger Publishing have reprinted the book in 2011)
William Martin Beauchamp, Iroquois folk lore: gathered from the Six Nations of New York, I. J. Friedman, 1965, pp. 152–53
Pages from Hopi history, Harry Clebourne James, University of Arizona Press, 1974, Chapter 6
Arizona and the West, Volume 17, University of Arizona Press., 1975, p. 179
Harold Osbourne, South American Mythology. New York: Peter Bedrick Books, 1986, pp. 42, 119
Stableford, Brian M. (2006). . Taylor & Francis. pp. 137–139. ISBN 978-0-415-97460-8.
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 195, 1692, pp 563–578
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 347 (1716), pp. 406–28
Migration Legend of the Creek Indians, Volumes 1–2, Albert S. Gatschet, Ams Pr Inc, 1969
The Franco-American review, Volumes 1–2, the Yale University Press, 1938, p. 111. Also see The Venus Calendar Observatory at Aztec New Mexico, Allan Macgillivray III, 2010, p. 25
Sandifer, Edward (April 2007). "Euler and the Hollow Earth: Fact or Fiction?" (PDF). . pp. 209–214. Retrieved 12 September 2021.
"Hollow Earth Monument | Atlas Obscura: John Symmes Hollow Earth monument". atlasobscura.com. Retrieved 1 November 2015.
Simon, Matt. "Fantastically Wrong: The Real-Life Journey to the Center of the Earth That Almost Was". Retrieved 18 September 2019.
"Jules Verne – Voyage au centre de la Terre – Chapitre 30. - Translation (French – English) – WebLitera – library of translations".
A Journey to the Earth's Interior, Marshall Gardner, Mokelumne Hill Pr, 1974 Edition, ISBN 0-7873-1192-8
Paget Walburga, Colloquies with an unseen friend, William Rider & Son., London., 1909., p. 36
Ferdynand Ossendowski (1922). Beasts, Men and Gods. New York: E. P. Dutton & Company.
George & Helen Papashvily, – Anything Can Happen., Harper & Bros., New York, NY., 1940
Cave of the Ancients, Lobsang Rampa, Random House, 1993
There are Giants in the Earth, Michael Grumley, Panther Books, 1976, pp. 42–47
Peter Kolosimo, Not of this World, Sphere Books 1974 ISBN 0-7221-5309-0 also see Peter Kolosimo, Timeless Earth, Citadel Pr, 1988 Edition ISBN 0-8065-1070-6
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Walter Kafton-Minkel Loompanics Unlimited, 1989 ISBN 978-1559500159
David Hatcher Childress Adventures Unlimited Press, 1998 ISBN 978-0932813633
Alien races and Fantastic Civilizations., Serge Hutin, Berkeley Medallion Books, 1975, pp. 109–132 – In the Bowels of the Earth: Refers to the mysterious catacombs beneath Paris, and other underground mysteries which lead inside the Earth.
The Under-People, Eric Norman, Award Books, 1969
Inner Earth People And Outer Space People, William L. Blessing, Inner Light Publications, 2008 Edition ISBN 1-60611-036-5
Chinese ghouls and goblins, G Willoughby-Meade, Stokes co, 1929
Mysteries of Ancient South America, Harold T. Wilkins, Citadel Press., New York, 1956
"Fantastically Wrong: The Legendary Scientist Who Swore Our Planet Is Hollow | WIRED". . wired.com. 2014-07-02. Retrieved 1 November 2015.
Kuiper, Gerard. P. (June 1946). "German Astronomy during the War". . 54: 263–86. Bibcode:1946PA.....54..263K. See pp. 277–78.
Yenne, William (2003). "Adolf Hitler and the Concave Earth Cult". . New York: Berkley Books. pp. 271–72. ISBN 978-0-425-18992-4.
Abdelkader, M. (1983). "A Geocosmos: Mapping Outer Space Into a Hollow Earth". (6): 81–89.
(Oct. 1981 and Feb. 1982).
(1992), Martin Gardner, pp. 18–19
On the Wild Side, 1992, Martin Gardner.
Press, Frank; Siever, Raymond; Grotzinger, John; Jordan, Tom (2003). (4 ed.). New York, New York: W. H. Freeman. pp. 484–87. ISBN 978-0-7167-9617-6.
"The Interior of the Earth". pubs.usgs.gov. Retrieved 1 November 2015.
"What's At The Bottom Of The Deepest Hole On Earth?". Retrieved 2016-08-17.
At the Earth's Core, by Edgar Rice Burroughs
Buchwald, Dagmar (2012). "Black Sun Underground: The Music of AlieNation". In Berressem, Hanjo; Bucher, Michael; Schwagmeier, Uwe (eds.). . LIT Verlag Munster. p. 109. ISBN 978-3-643-90228-3.
Thorgerson, Storm; Powell, Aubrey (1999). . DK Publishing. p. 20. ISBN 0-7894-4951-X.
Bibliography
Seaborn, Captain Adam. . J. Seymour, 1820.
Lewis, David. . Science Research Publishing House, 1979.
Kafton-Minkel, Walter. . Loompanics Unlimited, 1989.
Standish, David. . Da Capo Press, 2006.
Lamprecht, Jan. Grave Distraction Publications, 2014.
External links

The concept of a hollow Earth still recurs in folklore and as a premise for subterranean fiction, a subgenre of adventure fiction.

Contents
1 Hypothesis
1.1 16th to 18th centuries
1.2 19th century
1.3 20th century
1.4 Concave Hollow Earths
2 Schiehallion experiment
3 Contrary evidence
3.1 Seismic
3.2 Gravity
3.3 Direct observation
4 In fiction
5 In popular art
6 See also
7 References
8 Bibliography
9 External links
Hypothesis
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.[1][2] According to one story from Tibetan Buddhist tradition, there is an ancient city called Shamballa which is located inside the Earth.[2]

According to the Ancient Greeks, there were caverns under the surface which were entrances leading to the underworld, some of which were the caverns at Tainaron in Lakonia, at Troezen in Argolis, at Ephya in Thesprotia, at Herakleia in Pontos, and in Ermioni.[3] In Thracian and Dacian legends, it is said that there are caverns occupied by an ancient god called Zalmoxis.[4] 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.[5]

Chapel, bell tower and penitential beds on Station Island. 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 according to legend strange creatures would emerge and be seen on the surface of the Earth.[6] 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.[7] 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.[8]

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.[9] The Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground.[10]

Natives of the Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula".[11] 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.[12]

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.[13] The Italian writer Dante describes a hollow earth in his well-known 14th-century work , in which the fall of Lucifer from heaven caused an enormous funnel to appear in a 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 at the north side of the Missouri River.[14] 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.[15] It is also the belief of the tribes of the Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth.[16] The elders of the Hopi people believe that a Sipapu entrance in the Grand Canyon exists which leads to the underworld.[17][18]

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.[19]

16th to 18th centuries

Edmond Halley's hypothesis
The following lines from Act 3, Scene 2 of Shakespeare's play , written in London in 1595/6, suggest that the idea may have been known in Western Europe 100 years before it took on a more scientific form: Hermia: 'I'll believe as soon / This whole earth may be bored and that the moon / May through the center creep and so displease / Her brother's noontide with Antipodes.'

The notion was further popularized by Athanasius Kircher's non-fiction (1665), who speculated that there is an "intricate system of cavities and a channel of water connecting the poles".[20]: 137 

Edmond Halley in 1692[21] conjectured that the Earth might consist of a hollow shell about 800 km (500 mi) 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.[22]

Le Clerc Milfort in 1781 led a journey with hundreds of Creek Indians to a series of caverns near the Red River above the junction of the Mississippi River. According to Milfort the original Creek Indian ancestors are believed to have emerged out to the surface of the Earth in ancient times from the caverns. Milfort also claimed the caverns they saw "could easily contain 15,000 – 20,000 families."[23][24]

It is often claimed that mathematician Leonhard Euler proposed a single-shell hollow Earth with a small sun (1.000 kilometres across) at the centre, providing light and warmth for an inner-Earth civilisation, but that is not true. He did a thought experiment of an object dropped at a hole drilled trough the centre.[25]

19th century
In 1818, John Cleves Symmes, Jr. suggested that the Earth consisted of a hollow shell about 1,300 km (810 mi) thick, with openings about 2,300 km (1,400 mi) 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.[26] He proposed making an expedition to the North Pole hole,[27] thanks to efforts of one of his followers, James McBride.

Jeremiah 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 about his ideas, several authors published works discussing his ideas. McBride wrote in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: In 1868, a professor W.F. Lyons published which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Symmes's son Americus then published in 1878 to set the record straight.

Sir John Leslie proposed a hollow Earth in his 1829 (pp. 449–53).

In 1864, in [28] Jules Verne describes a hollow Earth containing two rotating binary stars, named Pluto and Proserpine.

William Fairfield Warren, in his book (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.[29]

20th century
, first serialized in a newspaper printed in Topeka, Kansas in 1900 and considered an early feminist utopian novel, mentions John Cleves Symmes' theory to explain its setting in a hollow Earth.

An early 20th-century proponent of hollow Earth, William Reed, wrote in 1906. He supported the idea of a hollow Earth, but without interior shells or inner sun.

The spiritualist writer Walburga, Lady Paget in her book (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.[30]

Marshall Gardner wrote 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 (U.S. Patent 1,096,102). Gardner made no mention of Reed, but did criticize Symmes for his ideas. Around the same time, Vladimir Obruchev wrote a novel titled , 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 wrote a book in 1922 titled . Ossendowski said he was told about a subterranean kingdom that exists inside the Earth. It was known to Buddhists as Agharti.[31]

George Papashvily in his (1940) claimed the discovery in the Caucasus mountains of 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.[32]

Novelist Lobsang Rampa in his book said an underground chamber system exists beneath the Himalayas of Tibet, filled with ancient machinery, records and treasure.[33] Michael Grumley, a cryptozoologist, has linked Bigfoot and other hominid cryptids to ancient tunnel systems underground.[34]

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.[35] Kolosimo and other ancient astronaut writers such as Robert Charroux linked these activities to UFOs.

A book by a "Dr. Raymond Bernard" which appeared in 1964, , exemplifies the idea of UFOs coming from inside the Earth, and adds the idea that the Ring Nebula proves the existence of hollow worlds, as well as speculation on the fate of Atlantis and the origin of flying saucers.[36][37] An article by Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's did the full story of Bernard/Siegmeister become well-known.[38]

The science fiction pulp magazine 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 pre-historic 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. The writer David Hatcher Childress authored (1998) in which he reprinted the stories of Palmer and defended the Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia.[39]

Hollow Earth proponents have claimed a number of different locations for the entrances which lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France,[40] Staffordshire in England,[41] Montreal in Canada,[42] Hangchow in China,[43] and the Amazon Rainforest.[44]

Concave Hollow Earths

An example of a concave hollow Earth. Humans live on the interior, with the universe in the center
Instead of saying that humans live on the outside surface of a hollow planet—sometimes called a "convex" Hollow Earth hypothesis—some have claimed humans live on the surface of a hollow spherical world, so that our universe itself lies in that world's interior. 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".[45] 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 . It has even been reported, although apparently without historical documentation, that Adolf Hitler was 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.[46][47]

The Egyptian mathematician Mostafa Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model.[48][49]

In one chapter of his book (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, which corresponds to no point a finite distance away from Earth in the widely accepted scientific cosmology. 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 in the widely accepted scientific cosmology. Supposedly no experiment can distinguish between the two cosmologies.

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.[50]

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 go to 2/ where 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.[51]

Schiehallion experiment
Main article: Schiehallion experiment
In 1735, Pierre Bouguer and Charles Marie de La Condamine chartered an expedition from France to the Chimborazo volcano in Ecuador. Arriving and climbing the volcano in 1738, they conducted a vertical deflection experiment at two different altitudes to determine how local mass anomalies affected gravitational pull. In a paper Bouguer wrote a little over ten years later, Bouguer commented that his results had at least falsified the Hollow Earth Theory. In 1772, Nevil Maskelyne proposed to repeat the same experiment to the Royal Society. Within the same year, the Committee of Attraction was formed and they sent Charles Mason to find the perfect candidate for the vertical deflection experiment. Mason found the Schiehallion mountain, where the experiment took place and not only supported the earlier Chimborazo Experiment but yielded far greater results.

Contrary evidence
Seismic
The picture of the structure of the Earth that has been arrived at through the study of seismic waves[52] is quite different from a fully hollow Earth. The time it takes for seismic waves to travel through and around the Earth directly contradicts a fully hollow sphere. The evidence indicates the Earth is mostly filled with solid rock (mantle and crust), liquid nickel-iron alloy (outer core), and solid nickel-iron (inner core).[53]

Gravity
Main articles: Schiehallion experiment and Cavendish experiment
Another set of scientific arguments against a Hollow Earth or any hollow planet comes from gravity. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid spheroid is the best way in which to minimize the gravitational potential energy of a rotating physical object; having hollowness is unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve hydrostatic equilibrium with its own mass and would collapse.

Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm3, and typical densities of surface rocks are only half that (about 2.75 g/cm3). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13 g/cm3, which brings the average density of Earth to its observed value.

Direct observation
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the Kola Superdeep Borehole,[54] with a true vertical drill-depth of more than 7.5 miles (12 kilometers). However, the distance to the center of the Earth is nearly 4,000 miles (6,400 kilometers). Oil wells with longer depths are not vertical wells; the total depths quoted are measured depth (MD) or equivalently, along-hole depth (AHD) as these wells are deviated to horizontal. Their true vertical depth (TVD) is typically less than 2.5 miles (4 kilometers).

In fiction
Main article: Subterranean fiction
The idea of a hollow Earth is a common element of fiction, appearing as early as Ludvig Holberg's 1741 novel (Niels Klim's Underground Travels), in which Nicolai Klim falls through a cave while spelunking and spends several years living on a smaller globe both within and the inside of the outer shell.

Other notable early examples include Giacomo Casanova's 1788 , a 5-volume, 1,800-page story of a brother and sister who fall into the Earth and discover the subterranean utopia of the Mégamicres, a race of multicolored, hermaphroditic dwarves; published anonymously in 1819; by a "Captain Adam Seaborn" (1820) which reflected the ideas of John Cleves Symmes, Jr.; Edgar Allan Poe's 1838 novel Jules Verne's 1864 novel which showed a subterranean world teeming with prehistoric life; George Sand's 1864 novel where giant crystals could be found in the interior of the Earth; , an 1895 science-fiction allegory with major subterranean themes; and , a 1908 novel that included the idea that the North Pole was the entrance to the hollow planet.

In William Henry Hudson's 1887 romance, , the protagonist falls down a hill into a Utopian paradise; since he falls into this world, it is sometimes classified as a hollow Earth story; although the hero himself thinks he may have traveled forward in time by millennia.

The idea was used by Edgar Rice Burroughs in the seven-novel "Pellucidar" series, beginning with (1914). Using a mechanical drill, called the Iron Mole, his heroes David Innes and Professor Abner Perry discover a prehistoric world called Pellucidar, 500 miles below the surface, that is lit by a constant noonday inner sun. They find prehistoric people, dinosaurs, prehistoric mammals and the Mahar, who evolved from pterosaurs. The series ran for six more books, ending with (1963).[55] The 1915 novel by Vladimir Obruchev uses the concept of the Hollow Earth to take the reader through various geological epochs.

In recent decades, the idea has become a staple of the science fiction and adventure genres across films ( and the MonsterVerse), television programs (the third and fourth seasons of ), role-playing games (e.g., the Hollow World Campaign Set for , ), and video games ( and ).

In popular art
In 1975 Japanese artist Tadanori Yokoo used elements of the Aghartha legend, along with other Eastern subterranean myths, to depict an advanced civilization in the cover art for jazz musician Miles Davis's album .[56] Tadanori said he was partly inspired by his reading of Raymond W. Bernard's 1969 book .[57]

See also
Brinsley Le Poer Trench, 8th Earl of Clancarty - 1974 proponent of Hollow Earth
Dyson sphere
Expanding Earth
Flat Earth
Hades
Hollow Moon
List of topics characterized as pseudoscience
Scientific skepticism
Shamballa
Shellworld
Travel to the Earth's center
Xibalba
References
Hollow Earth in the Puranas Online
The Way to Shambhala, Edwin Bernbaum, Anchor Books; 1st edition, 1980 ISBN 0-385-12794-4
Sherwood Fox, William (1916), , 1, Boston, Marshall Jones Company, p. 143
Mircea Eliade, Zalmoxis, the vanishing God: comparative studies in the religions and folklore of Dacia and Eastern Europe, 1959, pp. 24–30
Myth: its meaning and functions in ancient and other cultures, G. S. Kirk, 1970, p. 136
John A MacCulloch, Celtic Mythology, Rowman & Littlefield Pub Inc, 1932, pp. 125–26
T. Write, Saint Patrick's Purgatory : A medieval Pilgrimage in Ireland, 1918, p. 107
Harold Bayley, Archaic England: An Essay in Deciphering Prehistory from Megalithic Monuments, 1919 Online Edition: Link
Angami NagaBrown, Account of Munnipore, 1968., p. 113
Ellen Russell Emerson, Indian Myths, 1965 "It is to the Cubans we are indebted for the following version of man's origin: It was from the depths of a deep cavern in the earth that mankind issued."
Philip Freund, Myths of Creation; 1965, pp. 131–32
George, Wally – Pilgrimage To The Devil., Article in Fate magazine, Aug. 1957, pp. 38–52
Clark B Firestone and Ruth Hambidge, The Coasts of Ilusion, Harper & Bros; First Edition, 1924
Martha Warren Beckwith, Mandan-Hidatsa myths and ceremonies, G. E. Stechert, 1937, p. 10
Grenville Goodwin, Myths and Tales of the White Mountain Apache, 1939, p. 20 (Kessinger Publishing have reprinted the book in 2011)
William Martin Beauchamp, Iroquois folk lore: gathered from the Six Nations of New York, I. J. Friedman, 1965, pp. 152–53
Pages from Hopi history, Harry Clebourne James, University of Arizona Press, 1974, Chapter 6
Arizona and the West, Volume 17, University of Arizona Press., 1975, p. 179
Harold Osbourne, South American Mythology. New York: Peter Bedrick Books, 1986, pp. 42, 119
Stableford, Brian M. (2006). . Taylor & Francis. pp. 137–139. ISBN 978-0-415-97460-8.
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 195, 1692, pp 563–578
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 347 (1716), pp. 406–28
Migration Legend of the Creek Indians, Volumes 1–2, Albert S. Gatschet, Ams Pr Inc, 1969
The Franco-American review, Volumes 1–2, the Yale University Press, 1938, p. 111. Also see The Venus Calendar Observatory at Aztec New Mexico, Allan Macgillivray III, 2010, p. 25
Sandifer, Edward (April 2007). "Euler and the Hollow Earth: Fact or Fiction?" (PDF). . pp. 209–214. Retrieved 12 September 2021.
"Hollow Earth Monument | Atlas Obscura: John Symmes Hollow Earth monument". atlasobscura.com. Retrieved 1 November 2015.
Simon, Matt. "Fantastically Wrong: The Real-Life Journey to the Center of the Earth That Almost Was". Retrieved 18 September 2019.
"Jules Verne – Voyage au centre de la Terre – Chapitre 30. - Translation (French – English) – WebLitera – library of translations".
A Journey to the Earth's Interior, Marshall Gardner, Mokelumne Hill Pr, 1974 Edition, ISBN 0-7873-1192-8
Paget Walburga, Colloquies with an unseen friend, William Rider & Son., London., 1909., p. 36
Ferdynand Ossendowski (1922). Beasts, Men and Gods. New York: E. P. Dutton & Company.
George & Helen Papashvily, – Anything Can Happen., Harper & Bros., New York, NY., 1940
Cave of the Ancients, Lobsang Rampa, Random House, 1993
There are Giants in the Earth, Michael Grumley, Panther Books, 1976, pp. 42–47
Peter Kolosimo, Not of this World, Sphere Books 1974 ISBN 0-7221-5309-0 also see Peter Kolosimo, Timeless Earth, Citadel Pr, 1988 Edition ISBN 0-8065-1070-6
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Walter Kafton-Minkel Loompanics Unlimited, 1989 ISBN 978-1559500159
David Hatcher Childress Adventures Unlimited Press, 1998 ISBN 978-0932813633
Alien races and Fantastic Civilizations., Serge Hutin, Berkeley Medallion Books, 1975, pp. 109–132 – In the Bowels of the Earth: Refers to the mysterious catacombs beneath Paris, and other underground mysteries which lead inside the Earth.
The Under-People, Eric Norman, Award Books, 1969
Inner Earth People And Outer Space People, William L. Blessing, Inner Light Publications, 2008 Edition ISBN 1-60611-036-5
Chinese ghouls and goblins, G Willoughby-Meade, Stokes co, 1929
Mysteries of Ancient South America, Harold T. Wilkins, Citadel Press., New York, 1956
"Fantastically Wrong: The Legendary Scientist Who Swore Our Planet Is Hollow | WIRED". . wired.com. 2014-07-02. Retrieved 1 November 2015.
Kuiper, Gerard. P. (June 1946). "German Astronomy during the War". . 54: 263–86. Bibcode:1946PA.....54..263K. See pp. 277–78.
Yenne, William (2003). "Adolf Hitler and the Concave Earth Cult". . New York: Berkley Books. pp. 271–72. ISBN 978-0-425-18992-4.
Abdelkader, M. (1983). "A Geocosmos: Mapping Outer Space Into a Hollow Earth". (6): 81–89.
(Oct. 1981 and Feb. 1982).
(1992), Martin Gardner, pp. 18–19
On the Wild Side, 1992, Martin Gardner.
Press, Frank; Siever, Raymond; Grotzinger, John; Jordan, Tom (2003). (4 ed.). New York, New York: W. H. Freeman. pp. 484–87. ISBN 978-0-7167-9617-6.
"The Interior of the Earth". pubs.usgs.gov. Retrieved 1 November 2015.
"What's At The Bottom Of The Deepest Hole On Earth?". Retrieved 2016-08-17.
At the Earth's Core, by Edgar Rice Burroughs
Buchwald, Dagmar (2012). "Black Sun Underground: The Music of AlieNation". In Berressem, Hanjo; Bucher, Michael; Schwagmeier, Uwe (eds.). . LIT Verlag Munster. p. 109. ISBN 978-3-643-90228-3.
Thorgerson, Storm; Powell, Aubrey (1999). . DK Publishing. p. 20. ISBN 0-7894-4951-X.
Bibliography
Seaborn, Captain Adam. . J. Seymour, 1820.
Lewis, David. . Science Research Publishing House, 1979This article is about the concept. For other uses, see Hollow Earth (disambiguation).

A cross-sectional drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel
The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproved, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.

It was still occasionally defended through the mid-19th century, notably by John Cleves Symmes Jr. and Jeremiah N. Reynolds, but by this time it was part of popular pseudoscience and no longer a scientifically viable hypothesis.

The concept of a hollow Earth still recurs in folklore and as a premise for subterranean fiction, a subgenre of adventure fiction.

Contents
1 Hypothesis
1.1 16th to 18th centuries
1.2 19th century
1.3 20th century
1.4 Concave Hollow Earths
2 Schiehallion experiment
3 Contrary evidence
3.1 Seismic
3.2 Gravity
3.3 Direct observation
4 In fiction
5 In popular art
6 See also
7 References
8 Bibliography
9 External links
Hypothesis
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.[1][2] According to one story from Tibetan Buddhist tradition, there is an ancient city called Shamballa which is located inside the Earth.[2]

According to the Ancient Greeks, there were caverns under the surface which were entrances leading to the underworld, some of which were the caverns at Tainaron in Lakonia, at Troezen in Argolis, at Ephya in Thesprotia, at Herakleia in Pontos, and in Ermioni.[3] In Thracian and Dacian legends, it is said that there are caverns occupied by an ancient god called Zalmoxis.[4] 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.[5]

Chapel, bell tower and penitential beds on Station Island. 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 according to legend strange creatures would emerge and be seen on the surface of the Earth.[6] 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.[7] 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.[8]

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.[9] The Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground.[10]

Natives of the Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula".[11] 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.[12]

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.[13] The Italian writer Dante describes a hollow earth in his well-known 14th-century work , in which the fall of Lucifer from heaven caused an enormous funnel to appear in a 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 at the north side of the Missouri River.[14] 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.[15] It is also the belief of the tribes of the Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth.[16] The elders of the Hopi people believe that a Sipapu entrance in the Grand Canyon exists which leads to the underworld.[17][18]

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.[19]

16th to 18th centuries

Edmond Halley's hypothesis
The following lines from Act 3, Scene 2 of Shakespeare's play , written in London in 1595/6, suggest that the idea may have been known in Western Europe 100 years before it took on a more scientific form: Hermia: 'I'll believe as soon / This whole earth may be bored and that the moon / May through the center creep and so displease / Her brother's noontide with Antipodes.'

The notion was further popularized by Athanasius Kircher's non-fiction (1665), who speculated that there is an "intricate system of cavities and a channel of water connecting the poles".[20]: 137 

Edmond Halley in 1692[21] conjectured that the Earth might consist of a hollow shell about 800 km (500 mi) 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.[22]

Le Clerc Milfort in 1781 led a journey with hundreds of Creek Indians to a series of caverns near the Red River above the junction of the Mississippi River. According to Milfort the original Creek Indian ancestors are believed to have emerged out to the surface of the Earth in ancient times from the caverns. Milfort also claimed the caverns they saw "could easily contain 15,000 – 20,000 families."[23][24]

It is often claimed that mathematician Leonhard Euler proposed a single-shell hollow Earth with a small sun (1.000 kilometres across) at the centre, providing light and warmth for an inner-Earth civilisation, but that is not true. He did a thought experiment of an object dropped at a hole drilled trough the centre.[25]

19th century
In 1818, John Cleves Symmes, Jr. suggested that the Earth consisted of a hollow shell about 1,300 km (810 mi) thick, with openings about 2,300 km (1,400 mi) 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.[26] He proposed making an expedition to the North Pole hole,[27] thanks to efforts of one of his followers, James McBride.

Jeremiah 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 about his ideas, several authors published works discussing his ideas. McBride wrote in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: In 1868, a professor W.F. Lyons published which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Symmes's son Americus then published in 1878 to set the record straight.

Sir John Leslie proposed a hollow Earth in his 1829 (pp. 449–53).

In 1864, in [28] Jules Verne describes a hollow Earth containing two rotating binary stars, named Pluto and Proserpine.

William Fairfield Warren, in his book (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.[29]

20th century
, first serialized in a newspaper printed in Topeka, Kansas in 1900 and considered an early feminist utopian novel, mentions John Cleves Symmes' theory to explain its setting in a hollow Earth.

An early 20th-century proponent of hollow Earth, William Reed, wrote in 1906. He supported the idea of a hollow Earth, but without interior shells or inner sun.

The spiritualist writer Walburga, Lady Paget in her book (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.[30]

Marshall Gardner wrote 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 (U.S. Patent 1,096,102). Gardner made no mention of Reed, but did criticize Symmes for his ideas. Around the same time, Vladimir Obruchev wrote a novel titled , 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 wrote a book in 1922 titled . Ossendowski said he was told about a subterranean kingdom that exists inside the Earth. It was known to Buddhists as Agharti.[31]

George Papashvily in his (1940) claimed the discovery in the Caucasus mountains of 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.[32]

Novelist Lobsang Rampa in his book said an underground chamber system exists beneath the Himalayas of Tibet, filled with ancient machinery, records and treasure.[33] Michael Grumley, a cryptozoologist, has linked Bigfoot and other hominid cryptids to ancient tunnel systems underground.[34]

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.[35] Kolosimo and other ancient astronaut writers such as Robert Charroux linked these activities to UFOs.

A book by a "Dr. Raymond Bernard" which appeared in 1964, , exemplifies the idea of UFOs coming from inside the Earth, and adds the idea that the Ring Nebula proves the existence of hollow worlds, as well as speculation on the fate of Atlantis and the origin of flying saucers.[36][37] An article by Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's did the full story of Bernard/Siegmeister become well-known.[38]

The science fiction pulp magazine 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 pre-historic 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. The writer David Hatcher Childress authored (1998) in which he reprinted the stories of Palmer and defended the Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia.[39]

Hollow Earth proponents have claimed a number of different locations for the entrances which lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France,[40] Staffordshire in England,[41] Montreal in Canada,[42] Hangchow in China,[43] and the Amazon Rainforest.[44]

Concave Hollow Earths

An example of a concave hollow Earth. Humans live on the interior, with the universe in the center
Instead of saying that humans live on the outside surface of a hollow planet—sometimes called a "convex" Hollow Earth hypothesis—some have claimed humans live on the surface of a hollow spherical world, so that our universe itself lies in that world's interior. 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".[45] 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 . It has even been reported, although apparently without historical documentation, that Adolf Hitler was 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.[46][47]

The Egyptian mathematician Mostafa Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model.[48][49]

In one chapter of his book (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, which corresponds to no point a finite distance away from Earth in the widely accepted scientific cosmology. 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 in the widely accepted scientific cosmology. Supposedly no experiment can distinguish between the two cosmologies.

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.[50]

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 go to 2/ where 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.[51]

Schiehallion experiment
Main article: Schiehallion experiment
In 1735, Pierre Bouguer and Charles Marie de La Condamine chartered an expedition from France to the Chimborazo volcano in Ecuador. Arriving and climbing the volcano in 1738, they conducted a vertical deflection experiment at two different altitudes to determine how local mass anomalies affected gravitational pull. In a paper Bouguer wrote a little over ten years later, Bouguer commented that his results had at least falsified the Hollow Earth Theory. In 1772, Nevil Maskelyne proposed to repeat the same experiment to the Royal Society. Within the same year, the Committee of Attraction was formed and they sent Charles Mason to find the perfect candidate for the vertical deflection experiment. Mason found the Schiehallion mountain, where the experiment took place and not only supported the earlier Chimborazo Experiment but yielded far greater results.

Contrary evidence
Seismic
The picture of the structure of the Earth that has been arrived at through the study of seismic waves[52] is quite different from a fully hollow Earth. The time it takes for seismic waves to travel through and around the Earth directly contradicts a fully hollow sphere. The evidence indicates the Earth is mostly filled with solid rock (mantle and crust), liquid nickel-iron alloy (outer core), and solid nickel-iron (inner core).[53]

Gravity
Main articles: Schiehallion experiment and Cavendish experiment
Another set of scientific arguments against a Hollow Earth or any hollow planet comes from gravity. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid spheroid is the best way in which to minimize the gravitational potential energy of a rotating physical object; having hollowness is unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve hydrostatic equilibrium with its own mass and would collapse.

Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm3, and typical densities of surface rocks are only half that (about 2.75 g/cm3). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13 g/cm3, which brings the average density of Earth to its observed value.

Direct observation
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the Kola Superdeep Borehole,[54] with a true vertical drill-depth of more than 7.5 miles (12 kilometers). However, the distance to the center of the Earth is nearly 4,000 miles (6,400 kilometers). Oil wells with longer depths are not vertical wells; the total depths quoted are measured depth (MD) or equivalently, along-hole depth (AHD) as these wells are deviated to horizontal. Their true vertical depth (TVD) is typically less than 2.5 miles (4 kilometers).

In fiction
Main article: Subterranean fiction
The idea of a hollow Earth is a common element of fiction, appearing as early as Ludvig Holberg's 1741 novel (Niels Klim's Underground Travels), in which Nicolai Klim falls through a cave while spelunking and spends several years living on a smaller globe both within and the inside of the outer shell.

Other notable early examples include Giacomo Casanova's 1788 , a 5-volume, 1,800-page story of a brother and sister who fall into the Earth and discover the subterranean utopia of the Mégamicres, a race of multicolored, hermaphroditic dwarves; published anonymously in 1819; by a "Captain Adam Seaborn" (1820) which reflected the ideas of John Cleves Symmes, Jr.; Edgar Allan Poe's 1838 novel Jules Verne's 1864 novel which showed a subterranean world teeming with prehistoric life; George Sand's 1864 novel where giant crystals could be found in the interior of the Earth; , an 1895 science-fiction allegory with major subterranean themes; and , a 1908 novel that included the idea that the North Pole was the entrance to the hollow planet.

In William Henry Hudson's 1887 romance, , the protagonist falls down a hill into a Utopian paradise; since he falls into this world, it is sometimes classified as a hollow Earth story; although the hero himself thinks he may have traveled forward in time by millennia.

The idea was used by Edgar Rice Burroughs in the seven-novel "Pellucidar" series, beginning with (1914). Using a mechanical drill, called the Iron Mole, his heroes David Innes and Professor Abner Perry discover a prehistoric world called Pellucidar, 500 miles below the surface, that is lit by a constant noonday inner sun. They find prehistoric people, dinosaurs, prehistoric mammals and the Mahar, who evolved from pterosaurs. The series ran for six more books, ending with (1963).[55] The 1915 novel by Vladimir Obruchev uses the concept of the Hollow Earth to take the reader through various geological epochs.

In recent decades, the idea has become a staple of the science fiction and adventure genres across films ( and the MonsterVerse), television programs (the third and fourth seasons of ), role-playing games (e.g., the Hollow World Campaign Set for , ), and video games ( and ).

In popular art
In 1975 Japanese artist Tadanori Yokoo used elements of the Aghartha legend, along with other Eastern subterranean myths, to depict an advanced civilization in the cover art for jazz musician Miles Davis's album .[56] Tadanori said he was partly inspired by his reading of Raymond W. Bernard's 1969 book .[57]

See also
Brinsley Le Poer Trench, 8th Earl of Clancarty - 1974 proponent of Hollow Earth
Dyson sphere
Expanding Earth
Flat Earth
Hades
Hollow Moon
List of topics characterized as pseudoscience
Scientific skepticism
Shamballa
Shellworld
Travel to the Earth's center
Xibalba
References
Hollow Earth in the Puranas Online
The Way to Shambhala, Edwin Bernbaum, Anchor Books; 1st edition, 1980 ISBN 0-385-12794-4
Sherwood Fox, William (1916), , 1, Boston, Marshall Jones Company, p. 143
Mircea Eliade, Zalmoxis, the vanishing God: comparative studies in the religions and folklore of Dacia and Eastern Europe, 1959, pp. 24–30
Myth: its meaning and functions in ancient and other cultures, G. S. Kirk, 1970, p. 136
John A MacCulloch, Celtic Mythology, Rowman & Littlefield Pub Inc, 1932, pp. 125–26
T. Write, Saint Patrick's Purgatory : A medieval Pilgrimage in Ireland, 1918, p. 107
Harold Bayley, Archaic England: An Essay in Deciphering Prehistory from Megalithic Monuments, 1919 Online Edition: Link
Angami NagaBrown, Account of Munnipore, 1968., p. 113
Ellen Russell Emerson, Indian Myths, 1965 "It is to the Cubans we are indebted for the following version of man's origin: It was from the depths of a deep cavern in the earth that mankind issued."
Philip Freund, Myths of Creation; 1965, pp. 131–32
George, Wally – Pilgrimage To The Devil., Article in Fate magazine, Aug. 1957, pp. 38–52
Clark B Firestone and Ruth Hambidge, The Coasts of Ilusion, Harper & Bros; First Edition, 1924
Martha Warren Beckwith, Mandan-Hidatsa myths and ceremonies, G. E. Stechert, 1937, p. 10
Grenville Goodwin, Myths and Tales of the White Mountain Apache, 1939, p. 20 (Kessinger Publishing have reprinted the book in 2011)
William Martin Beauchamp, Iroquois folk lore: gathered from the Six Nations of New York, I. J. Friedman, 1965, pp. 152–53
Pages from Hopi history, Harry Clebourne James, University of Arizona Press, 1974, Chapter 6
Arizona and the West, Volume 17, University of Arizona Press., 1975, p. 179
Harold Osbourne, South American Mythology. New York: Peter Bedrick Books, 1986, pp. 42, 119
Stableford, Brian M. (2006). . Taylor & Francis. pp. 137–139. ISBN 978-0-415-97460-8.
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 195, 1692, pp 563–578
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 347 (1716), pp. 406–28
Migration Legend of the Creek Indians, Volumes 1–2, Albert S. Gatschet, Ams Pr Inc, 1969
The Franco-American review, Volumes 1–2, the Yale University Press, 1938, p. 111. Also see The Venus Calendar Observatory at Aztec New Mexico, Allan Macgillivray III, 2010, p. 25
Sandifer, Edward (April 2007). "Euler and the Hollow Earth: Fact or Fiction?" (PDF). . pp. 209–214. Retrieved 12 September 2021.
"Hollow Earth Monument | Atlas Obscura: John Symmes Hollow Earth monument". atlasobscura.com. Retrieved 1 November 2015.
Simon, Matt. "Fantastically Wrong: The Real-Life Journey to the Center of the Earth That Almost Was". Retrieved 18 September 2019.
"Jules Verne – Voyage au centre de la Terre – Chapitre 30. - Translation (French – English) – WebLitera – library of translations".
A Journey to the Earth's Interior, Marshall Gardner, Mokelumne Hill Pr, 1974 Edition, ISBN 0-7873-1192-8
Paget Walburga, Colloquies with an unseen friend, William Rider & Son., London., 1909., p. 36
Ferdynand Ossendowski (1922). Beasts, Men and Gods. New York: E. P. Dutton & Company.
George & Helen Papashvily, – Anything Can Happen., Harper & Bros., New York, NY., 1940
Cave of the Ancients, Lobsang Rampa, Random House, 1993
There are Giants in the Earth, Michael Grumley, Panther Books, 1976, pp. 42–47
Peter Kolosimo, Not of this World, Sphere Books 1974 ISBN 0-7221-5309-0 also see Peter Kolosimo, Timeless Earth, Citadel Pr, 1988 Edition ISBN 0-8065-1070-6
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Walter Kafton-Minkel Loompanics Unlimited, 1989 ISBN 978-1559500159
David Hatcher Childress Adventures Unlimited Press, 1998 ISBN 978-0932813633
Alien races and Fantastic Civilizations., Serge Hutin, Berkeley Medallion Books, 1975, pp. 109–132 – In the Bowels of the Earth: Refers to the mysterious catacombs beneath Paris, and other underground mysteries which lead inside the Earth.
The Under-People, Eric Norman, Award Books, 1969
Inner Earth People And Outer Space People, William L. Blessing, Inner Light Publications, 2008 Edition ISBN 1-60611-036-5
Chinese ghouls and goblins, G Willoughby-Meade, Stokes co, 1929
Mysteries of Ancient South America, Harold T. Wilkins, Citadel Press., New York, 1956
"Fantastically Wrong: The Legendary Scientist Who Swore Our Planet Is Hollow | WIRED". . wired.com. 2014-07-02. Retrieved 1 November 2015.
Kuiper, Gerard. P. (June 1946). "German Astronomy during the War". . 54: 263–86. Bibcode:1946PA.....54..263K. See pp. 277–78.
Yenne, William (2003). "Adolf Hitler and the Concave Earth Cult". . New York: Berkley Books. pp. 271–72. ISBN 978-0-425-18992-4.
Abdelkader, M. (1983). "A Geocosmos: Mapping Outer Space Into a Hollow Earth". (6): 81–89.
(Oct. 1981 and Feb. 1982).
(1992), Martin Gardner, pp. 18–19
On the Wild Side, 1992, Martin Gardner.
Press, Frank; Siever, Raymond; Grotzinger, John; Jordan, Tom (2003). (4 ed.). New York, New York: W. H. Freeman. pp. 484–87. ISBN 978-0-7167-9617-6.
"The Interior of the Earth". pubs.usgs.gov. Retrieved 1 November 2015.
"What's At The Bottom Of The Deepest Hole On Earth?". Retrieved 2016-08-17.
At the Earth's Core, by Edgar Rice Burroughs
Buchwald, Dagmar (2012). "Black Sun Underground: The Music of AlieNation". In Berressem, Hanjo; Bucher, Michael; Schwagmeier, Uwe (eds.). . LIT Verlag Munster. p. 109. ISBN 978-3-643-90228-3.
Thorgerson, Storm; Powell, Aubrey (1999). . DK Publishing. p. 20. ISBN 0-7894-4951-X.
Bibliography
Seaborn, Captain Adam. . J. Seymour, 1820.
Lewis, David. . Science Research Publishing House, 1979.
Kafton-Minkel, Walter. . Loompanics Unlimited, 1989.
Standish, David. . Da Capo Press, 2006.
Lamprecht, Jan. Grave Distraction Publications, 2014.
External links
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Kafton-Minkel, Walter. . Loompanics Unlimited, 1989.
Standish, David. . Da Capo Press, 2006.
Lamprecht, Jan. Grave Distraction Publications, 2014.
External linksThis article is about the concept. For other uses, see Hollow Earth (disambiguation).

A cross-sectional drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel
The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproved, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.

It was still occasionally defended through the mid-19th century, notably by John Cleves Symmes Jr. and Jeremiah N. Reynolds, but by this time it was part of popular pseudoscience and no longer a scientifically viable hypothesis.

The concept of a hollow Earth still recurs in folklore and as a premise for subterranean fiction, a subgenre of adventure fiction.

Contents
1 Hypothesis
1.1 16th to 18th centuries
1.2 19th century
1.3 20th century
1.4 Concave Hollow Earths
2 Schiehallion experiment
3 Contrary evidence
3.1 Seismic
3.2 Gravity
3.3 Direct observation
4 In fiction
5 In popular art
6 See also
7 References
8 Bibliography
9 External links
Hypothesis
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.[1][2] According to one story from Tibetan Buddhist tradition, there is an ancient city called Shamballa which is located inside the Earth.[2]

According to the Ancient Greeks, there were caverns under the surface which were entrances leading to the underworld, some of which were the caverns at Tainaron in Lakonia, at Troezen in Argolis, at Ephya in Thesprotia, at Herakleia in Pontos, and in Ermioni.[3] In Thracian and Dacian legends, it is said that there are caverns occupied by an ancient god called Zalmoxis.[4] 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.[5]

Chapel, bell tower and penitential beds on Station Island. 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 according to legend strange creatures would emerge and be seen on the surface of the Earth.[6] 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.[7] 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.[8]

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.[9] The Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground.[10]

Natives of the Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula".[11] 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.[12]

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.[13] The Italian writer Dante describes a hollow earth in his well-known 14th-century work , in which the fall of Lucifer from heaven caused an enormous funnel to appear in a 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 at the north side of the Missouri River.[14] 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.[15] It is also the belief of the tribes of the Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth.[16] The elders of the Hopi people believe that a Sipapu entrance in the Grand Canyon exists which leads to the underworld.[17][18]

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.[19]

16th to 18th centuries

Edmond Halley's hypothesis
The following lines from Act 3, Scene 2 of Shakespeare's play , written in London in 1595/6, suggest that the idea may have been known in Western Europe 100 years before it took on a more scientific form: Hermia: 'I'll believe as soon / This whole earth may be bored and that the moon / May through the center creep and so displease / Her brother's noontide with Antipodes.'

The notion was further popularized by Athanasius Kircher's non-fiction (1665), who speculated that there is an "intricate system of cavities and a channel of water connecting the poles".[20]: 137 

Edmond Halley in 1692[21] conjectured that the Earth might consist of a hollow shell about 800 km (500 mi) 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.[22]

Le Clerc Milfort in 1781 led a journey with hundreds of Creek Indians to a series of caverns near the Red River above the junction of the Mississippi River. According to Milfort the original Creek Indian ancestors are believed to have emerged out to the surface of the Earth in ancient times from the caverns. Milfort also claimed the caverns they saw "could easily contain 15,000 – 20,000 families."[23][24]

It is often claimed that mathematician Leonhard Euler proposed a single-shell hollow Earth with a small sun (1.000 kilometres across) at the centre, providing light and warmth for an inner-Earth civilisation, but that is not true. He did a thought experiment of an object dropped at a hole drilled trough the centre.[25]

19th century
In 1818, John Cleves Symmes, Jr. suggested that the Earth consisted of a hollow shell about 1,300 km (810 mi) thick, with openings about 2,300 km (1,400 mi) 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.[26] He proposed making an expedition to the North Pole hole,[27] thanks to efforts of one of his followers, James McBride.

Jeremiah 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 about his ideas, several authors published works discussing his ideas. McBride wrote in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: In 1868, a professor W.F. Lyons published which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Symmes's son Americus then published in 1878 to set the record straight.

Sir John Leslie proposed a hollow Earth in his 1829 (pp. 449–53).

In 1864, in [28] Jules Verne describes a hollow Earth containing two rotating binary stars, named Pluto and Proserpine.

William Fairfield Warren, in his book (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.[29]

20th century
, first serialized in a newspaper printed in Topeka, Kansas in 1900 and considered an early feminist utopian novel, mentions John Cleves Symmes' theory to explain its setting in a hollow Earth.

An early 20th-century proponent of hollow Earth, William Reed, wrote in 1906. He supported the idea of a hollow Earth, but without interior shells or inner sun.

The spiritualist writer Walburga, Lady Paget in her book (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.[30]

Marshall Gardner wrote 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 (U.S. Patent 1,096,102). Gardner made no mention of Reed, but did criticize Symmes for his ideas. Around the same time, Vladimir Obruchev wrote a novel titled , 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 wrote a book in 1922 titled . Ossendowski said he was told about a subterranean kingdom that exists inside the Earth. It was known to Buddhists as Agharti.[31]

George Papashvily in his (1940) claimed the discovery in the Caucasus mountains of 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.[32]

Novelist Lobsang Rampa in his book said an underground chamber system exists beneath the Himalayas of Tibet, filled with ancient machinery, records and treasure.[33] Michael Grumley, a cryptozoologist, has linked Bigfoot and other hominid cryptids to ancient tunnel systems underground.[34]

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.[35] Kolosimo and other ancient astronaut writers such as Robert Charroux linked these activities to UFOs.

A book by a "Dr. Raymond Bernard" which appeared in 1964, , exemplifies the idea of UFOs coming from inside the Earth, and adds the idea that the Ring Nebula proves the existence of hollow worlds, as well as speculation on the fate of Atlantis and the origin of flying saucers.[36][37] An article by Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's did the full story of Bernard/Siegmeister become well-known.[38]

The science fiction pulp magazine 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 pre-historic 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. The writer David Hatcher Childress authored (1998) in which he reprinted the stories of Palmer and defended the Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia.[39]

Hollow Earth proponents have claimed a number of different locations for the entrances which lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France,[40] Staffordshire in England,[41] Montreal in Canada,[42] Hangchow in China,[43] and the Amazon Rainforest.[44]

Concave Hollow Earths

An example of a concave hollow Earth. Humans live on the interior, with the universe in the center
Instead of saying that humans live on the outside surface of a hollow planet—sometimes called a "convex" Hollow Earth hypothesis—some have claimed humans live on the surface of a hollow spherical world, so that our universe itself lies in that world's interior. 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".[45] 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 . It has even been reported, although apparently without historical documentation, that Adolf Hitler was 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.[46][47]

The Egyptian mathematician Mostafa Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model.[48][49]

In one chapter of his book (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, which corresponds to no point a finite distance away from Earth in the widely accepted scientific cosmology. 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 in the widely accepted scientific cosmology. Supposedly no experiment can distinguish between the two cosmologies.

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.[50]

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 go to 2/ where 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.[51]

Schiehallion experiment
Main article: Schiehallion experiment
In 1735, Pierre Bouguer and Charles Marie de La Condamine chartered an expedition from France to the Chimborazo volcano in Ecuador. Arriving and climbing the volcano in 1738, they conducted a vertical deflection experiment at two different altitudes to determine how local mass anomalies affected gravitational pull. In a paper Bouguer wrote a little over ten years later, Bouguer commented that his results had at least falsified the Hollow Earth Theory. In 1772, Nevil Maskelyne proposed to repeat the same experiment to the Royal Society. Within the same year, the Committee of Attraction was formed and they sent Charles Mason to find the perfect candidate for the vertical deflection experiment. Mason found the Schiehallion mountain, where the experiment took place and not only supported the earlier Chimborazo Experiment but yielded far greater results.

Contrary evidence
Seismic
The picture of the structure of the Earth that has been arrived at through the study of seismic waves[52] is quite different from a fully hollow Earth. The time it takes for seismic waves to travel through and around the Earth directly contradicts a fully hollow sphere. The evidence indicates the Earth is mostly filled with solid rock (mantle and crust), liquid nickel-iron alloy (outer core), and solid nickel-iron (inner core).[53]

Gravity
Main articles: Schiehallion experiment and Cavendish experiment
Another set of scientific arguments against a Hollow Earth or any hollow planet comes from gravity. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid spheroid is the best way in which to minimize the gravitational potential energy of a rotating physical object; having hollowness is unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve hydrostatic equilibrium with its own mass and would collapse.

Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm3, and typical densities of surface rocks are only half that (about 2.75 g/cm3). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13 g/cm3, which brings the average density of Earth to its observed value.

Direct observation
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the Kola Superdeep Borehole,[54] with a true vertical drill-depth of more than 7.5 miles (12 kilometers). However, the distance to the center of the Earth is nearly 4,000 miles (6,400 kilometers). Oil wells with longer depths are not vertical wells; the total depths quoted are measured depth (MD) or equivalently, along-hole depth (AHD) as these wells are deviated to horizontal. Their true vertical depth (TVD) is typically less than 2.5 miles (4 kilometers).

In fiction
Main article: Subterranean fiction
The idea of a hollow Earth is a common element of fiction, appearing as early as Ludvig Holberg's 1741 novel (Niels Klim's Underground Travels), in which Nicolai Klim falls through a cave while spelunking and spends several years living on a smaller globe both within and the inside of the outer shell.

Other notable early examples include Giacomo Casanova's 1788 , a 5-volume, 1,800-page story of a brother and sister who fall into the Earth and discover the subterranean utopia of the Mégamicres, a race of multicolored, hermaphroditic dwarves; published anonymously in 1819; by a "Captain Adam Seaborn" (1820) which reflected the ideas of John Cleves Symmes, Jr.; Edgar Allan Poe's 1838 novel Jules Verne's 1864 novel which showed a subterranean world teeming with prehistoric life; George Sand's 1864 novel where giant crystals could be found in the interior of the Earth; , an 1895 science-fiction allegory with major subterranean themes; and , a 1908 novel that included the idea that the North Pole was the entrance to the hollow planet.

In William Henry Hudson's 1887 romance, , the protagonist falls down a hill into a Utopian paradise; since he falls into this world, it is sometimes classified as a hollow Earth story; although the hero himself thinks he may have traveled forward in time by millennia.

The idea was used by Edgar Rice Burroughs in the seven-novel "Pellucidar" series, beginning with (1914). Using a mechanical drill, called the Iron Mole, his heroes David Innes and Professor Abner Perry discover a prehistoric world called Pellucidar, 500 miles below the surface, that is lit by a constant noonday inner sun. They find prehistoric people, dinosaurs, prehistoric mammals and the Mahar, who evolved from pterosaurs. The series ran for six more books, ending with (1963).[55] The 1915 novel by Vladimir Obruchev uses the concept of the Hollow Earth to take the reader through various geological epochs.

In recent decades, the idea has become a staple of the science fiction and adventure genres across films ( and the MonsterVerse), television programs (the third and fourth seasons of ), role-playing games (e.g., the Hollow World Campaign Set for , ), and video games ( and ).

In popular art
In 1975 Japanese artist Tadanori Yokoo used elements of the Aghartha legend, along with other Eastern subterranean myths, to depict an advanced civilization in the cover art for jazz musician Miles Davis's album .[56] Tadanori said he was partly inspired by his reading of Raymond W. Bernard's 1969 book .[57]

See also
Brinsley Le Poer Trench, 8th Earl of Clancarty - 1974 proponent of Hollow Earth
Dyson sphere
Expanding Earth
Flat Earth
Hades
Hollow Moon
List of topics characterized as pseudoscience
Scientific skepticism
Shamballa
Shellworld
Travel to the Earth's center
Xibalba
References
Hollow Earth in the Puranas Online
The Way to Shambhala, Edwin Bernbaum, Anchor Books; 1st edition, 1980 ISBN 0-385-12794-4
Sherwood Fox, William (1916), , 1, Boston, Marshall Jones Company, p. 143
Mircea Eliade, Zalmoxis, the vanishing God: comparative studies in the religions and folklore of Dacia and Eastern Europe, 1959, pp. 24–30
Myth: its meaning and functions in ancient and other cultures, G. S. Kirk, 1970, p. 136
John A MacCulloch, Celtic Mythology, Rowman & Littlefield Pub Inc, 1932, pp. 125–26
T. Write, Saint Patrick's Purgatory : A medieval Pilgrimage in Ireland, 1918, p. 107
Harold Bayley, Archaic England: An Essay in Deciphering Prehistory from Megalithic Monuments, 1919 Online Edition: Link
Angami NagaBrown, Account of Munnipore, 1968., p. 113
Ellen Russell Emerson, Indian Myths, 1965 "It is to the Cubans we are indebted for the following version of man's origin: It was from the depths of a deep cavern in the earth that mankind issued."
Philip Freund, Myths of Creation; 1965, pp. 131–32
George, Wally – Pilgrimage To The Devil., Article in Fate magazine, Aug. 1957, pp. 38–52
Clark B Firestone and Ruth Hambidge, The Coasts of Ilusion, Harper & Bros; First Edition, 1924
Martha Warren Beckwith, Mandan-Hidatsa myths and ceremonies, G. E. Stechert, 1937, p. 10
Grenville Goodwin, Myths and Tales of the White Mountain Apache, 1939, p. 20 (Kessinger Publishing have reprinted the book in 2011)
William Martin Beauchamp, Iroquois folk lore: gathered from the Six Nations of New York, I. J. Friedman, 1965, pp. 152–53
Pages from Hopi history, Harry Clebourne James, University of Arizona Press, 1974, Chapter 6
Arizona and the West, Volume 17, University of Arizona Press., 1975, p. 179
Harold Osbourne, South American Mythology. New York: Peter Bedrick Books, 1986, pp. 42, 119
Stableford, Brian M. (2006). . Taylor & Francis. pp. 137–139. ISBN 978-0-415-97460-8.
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 195, 1692, pp 563–578
Halley, Edmond, , Philosophical Transactions of Royal Society of London, No. 347 (1716), pp. 406–28
Migration Legend of the Creek Indians, Volumes 1–2, Albert S. Gatschet, Ams Pr Inc, 1969
The Franco-American review, Volumes 1–2, the Yale University Press, 1938, p. 111. Also see The Venus Calendar Observatory at Aztec New Mexico, Allan Macgillivray III, 2010, p. 25
Sandifer, Edward (April 2007). "Euler and the Hollow Earth: Fact or Fiction?" (PDF). . pp. 209–214. Retrieved 12 September 2021.
"Hollow Earth Monument | Atlas Obscura: John Symmes Hollow Earth monument". atlasobscura.com. Retrieved 1 November 2015.
Simon, Matt. "Fantastically Wrong: The Real-Life Journey to the Center of the Earth That Almost Was". Retrieved 18 September 2019.
"Jules Verne – Voyage au centre de la Terre – Chapitre 30. - Translation (French – English) – WebLitera – library of translations".
A Journey to the Earth's Interior, Marshall Gardner, Mokelumne Hill Pr, 1974 Edition, ISBN 0-7873-1192-8
Paget Walburga, Colloquies with an unseen friend, William Rider & Son., London., 1909., p. 36
Ferdynand Ossendowski (1922). Beasts, Men and Gods. New York: E. P. Dutton & Company.
George & Helen Papashvily, – Anything Can Happen., Harper & Bros., New York, NY., 1940
Cave of the Ancients, Lobsang Rampa, Random House, 1993
There are Giants in the Earth, Michael Grumley, Panther Books, 1976, pp. 42–47
Peter Kolosimo, Not of this World, Sphere Books 1974 ISBN 0-7221-5309-0 also see Peter Kolosimo, Timeless Earth, Citadel Pr, 1988 Edition ISBN 0-8065-1070-6
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Reece, Gregory L. (August 21, 2007). . I. B. Tauris. p. 17. ISBN 978-1-84511-451-0.
Walter Kafton-Minkel Loompanics Unlimited, 1989 ISBN 978-1559500159
David Hatcher Childress Adventures Unlimited Press, 1998 ISBN 978-0932813633
Alien races and Fantastic Civilizations., Serge Hutin, Berkeley Medallion Books, 1975, pp. 109–132 – In the Bowels of the Earth: Refers to the mysterious catacombs beneath Paris, and other underground mysteries which lead inside the Earth.
The Under-People, Eric Norman, Award Books, 1969
Inner Earth People And Outer Space People, William L. Blessing, Inner Light Publications, 2008 Edition ISBN 1-60611-036-5
Chinese ghouls and goblins, G Willoughby-Meade, Stokes co, 1929
Mysteries of Ancient South America, Harold T. Wilkins, Citadel Press., New York, 1956
"Fantastically Wrong: The Legendary Scientist Who Swore Our Planet Is Hollow | WIRED". . wired.com. 2014-07-02. Retrieved 1 November 2015.
Kuiper, Gerard. P. (June 1946). "German Astronomy during the War". . 54: 263–86. Bibcode:1946PA.....54..263K. See pp. 277–78.
Yenne, William (2003). "Adolf Hitler and the Concave Earth Cult". . New York: Berkley Books. pp. 271–72. ISBN 978-0-425-18992-4.
Abdelkader, M. (1983). "A Geocosmos: Mapping Outer Space Into a Hollow Earth". (6): 81–89.
(Oct. 1981 and Feb. 1982).
(1992), Martin Gardner, pp. 18–19
On the Wild Side, 1992, Martin Gardner.
Press, Frank; Siever, Raymond; Grotzinger, John; Jordan, Tom (2003). (4 ed.). New York, New York: W. H. Freeman. pp. 484–87. ISBN 978-0-7167-9617-6.
"The Interior of the Earth". pubs.usgs.gov. Retrieved 1 November 2015.
"What's At The Bottom Of The Deepest Hole On Earth?". Retrieved 2016-08-17.
At the Earth's Core, by Edgar Rice Burroughs
Buchwald, Dagmar (2012). "Black Sun Underground: The Music of AlieNation". In Berressem, Hanjo; Bucher, Michael; Schwagmeier, Uwe (eds.). . LIT Verlag Munster. p. 109. ISBN 978-3-643-90228-3.
Thorgerson, Storm; Powell, Aubrey (1999). . DK Publishing. p. 20. ISBN 0-7894-4951-X.
Bibliography
Seaborn, Captain Adam. . J. Seymour, 1820.
Lewis, David. . Science Research Publishing House, 1979.
Kafton-Minkel, Walter. . Loompanics Unlimited, 1989.
Standish, David. . Da Capo Press, 2006.
Lamprecht, Jan. Grave Distraction Publications, 2014.
External links

This article is about the concept. For other uses, see Hollow Earth (disambiguation).

A cross-sectional drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel
The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproved, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.

It was still occasionally defended through the mid-19th century, notably by John Cleves Symmes Jr. and Jeremiah N. Reynolds, but by this time it was part of popular pseudoscience and no longer a scientifically viable hypothesis.

The concept of a hollow Earth still recurs in folklore and as a premise for subterranean fiction, a subgenre of adventure fiction.

Contents
1 Hypothesis
1.1 16th to 18th centuries
1.2 19th century
1.3 20th century
1.4 Concave Hollow Earths
2 Schiehallion experiment
3 Contrary evidence
3.1 Seismic
3.2 Gravity
3.3 Direct observation
4 In fiction
5 In popular art
6 See also
7 References
8 Bibliography
9 External links
Hypothesis
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.[1][2] According to one story from Tibetan Buddhist tradition, there is an ancient city called Shamballa which is located inside the Earth.[2]

According to the Ancient Greeks, there were caverns under the surface which were entrances leading to the underworld, some of which were the caverns at Tainaron in Lakonia, at Troezen in Argolis, at Ephya in Thesprotia, at Herakleia in Pontos, and in Ermioni.[3] In Thracian and Dacian legends, it is said that there are caverns occupied by an ancient god called Zalmoxis.[4] 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.[5]

Chapel, bell tower and penitential beds on Station Island. 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 according to legend strange creatures would emerge and be seen on the surface of the Earth.[6] 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.[7] 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.[8]

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.[9] The Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground.[10]

Natives of the Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula".[11] 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.[12]

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.[13] The Italian writer Dante describes a hollow earth in his well-known 14th-century work , in which the fall of Lucifer from heaven caused an enormous funnel to appear in a 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 at the north side of the Missouri River.[14] 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.[15] It is also the belief of the tribes of the Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth.[16] The elders of the Hopi people believe that a Sipapu entrance in the Grand Canyon exists which leads to the underworld.[17][18]

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.[19]

16th to 18th centuries

Edmond Halley's hypothesis
The following lines from Act 3, Scene 2 of Shakespeare's play , written in London in 1595/6, suggest that the idea may have been known in Western Europe 100 years before it took on a more scientific form: Hermia: 'I'll believe as soon / This whole earth may be bored and that the moon / May through the center creep and so displease / Her brother's noontide with Antipodes.'

The notion was further popularized by Athanasius Kircher's non-fiction (1665), who speculated that there is an "intricate system of cavities and a channel of water connecting the poles".[20]: 137 

Edmond Halley in 1692[21] conjectured that the Earth might consist of a hollow shell about 800 km (500 mi) 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.[22]

Le Clerc Milfort in 1781 led a journey with hundreds of Creek Indians to a series of caverns near the Red River above the junction of the Mississippi River. According to Milfort the original Creek Indian ancestors are believed to have emerged out to the surface of the Earth in ancient times from the caverns. Milfort also claimed the caverns they saw "could easily contain 15,000 – 20,000 families."[23][24]

It is often claimed that mathematician Leonhard Euler proposed a single-shell hollow Earth with a small sun (1.000 kilometres across) at the centre, providing light and warmth for an inner-Earth civilisation, but that is not true. He did a thought experiment of an object dropped at a hole drilled trough the centre.[25]

19th century
In 1818, John Cleves Symmes, Jr. suggested that the Earth consisted of a hollow shell about 1,300 km (810 mi) thick, with openings about 2,300 km (1,400 mi) 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.[26] He proposed making an expedition to the North Pole hole,[27] thanks to efforts of one of his followers, James McBride.

Jeremiah 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 about his ideas, several authors published works discussing his ideas. McBride wrote in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: In 1868, a professor W.F. Lyons published which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Symmes's son Americus then published in 1878 to set the record straight.

Sir John Leslie proposed a hollow Earth in his 1829 (pp. 449–53).

In 1864, in [28] Jules Verne describes a hollow Earth containing two rotating binary stars, named Pluto and Proserpine.

William Fairfield Warren, in his book (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.[29]

20th century
, first serialized in a newspaper printed in Topeka, Kansas in 1900 and considered an early feminist utopian novel, mentions John Cleves Symmes' theory to explain its setting in a hollow Earth.

An early 20th-century proponent of hollow Earth, William Reed, wrote in 1906. He supported the idea of a hollow Earth, but without interior shells or inner sun.

The spiritualist writer Walburga, Lady Paget in her book (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.[30]

Marshall Gardner wrote 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 (U.S. Patent 1,096,102). Gardner made no mention of Reed, but did criticize Symmes for his ideas. Around the same time, Vladimir Obruchev wrote a novel titled , 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 wrote a book in 1922 titled . Ossendowski said he was told about a subterranean kingdom that exists inside the Earth. It was known to Buddhists as Agharti.[31]

George Papashvily in his (1940) claimed the discovery in the Caucasus mountains of 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.[32]

Novelist Lobsang Rampa in his book said an underground chamber system exists beneath the Himalayas of Tibet, filled with ancient machinery, records and treasure.[33] Michael Grumley, a cryptozoologist, has linked Bigfoot and other hominid cryptids to ancient tunnel systems underground.[34]

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.[35] Kolosimo and other ancient astronaut writers such as Robert Charroux linked these activities to UFOs.

A book by a "Dr. Raymond Bernard" which appeared in 1964, , exemplifies the idea of UFOs coming from inside the Earth, and adds the idea that the Ring Nebula proves the existence of hollow worlds, as well as speculation on the fate of Atlantis and the origin of flying saucers.[36][37] An article by Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's did the full story of Bernard/Siegmeister become well-known.[38]

The science fiction pulp magazine 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 pre-historic 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. The writer David Hatcher Childress authored (1998) in which he reprinted the stories of Palmer and defended the Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia.[39]

Hollow Earth proponents have claimed a number of different locations for the entrances which lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France,[40] Staffordshire in England,[41] Montreal in Canada,[42] Hangchow in China,[43] and the Amazon Rainforest.[44]

Concave Hollow Earths

An example of a concave hollow Earth. Humans live on the interior, with the universe in the center
Instead of saying that humans live on the outside surface of a hollow planet—sometimes called a "convex" Hollow Earth hypothesis—some have claimed humans live on the surface of a hollow spherical world, so that our universe itself lies in that world's interior. 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".[45] 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 . It has even been reported, although apparently without historical documentation, that Adolf Hitler was 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.[46][47]

The Egyptian mathematician Mostafa Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model.[48][49]

In one chapter of his book (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, which corresponds to no point a finite distance away from Earth in the widely accepted scientific cosmology. 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 in the widely accepted scientific cosmology. Supposedly no experiment can distinguish between the two cosmologies.

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.[50]

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 go to 2/ where 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.[51]

Schiehallion experiment
Main article: Schiehallion experiment
In 1735, Pierre Bouguer and Charles Marie de La Condamine chartered an expedition from France to the Chimborazo volcano in Ecuador. Arriving and climbing the volcano in 1738, they conducted a vertical deflection experiment at two different altitudes to determine how local mass anomalies affected gravitational pull. In a paper Bouguer wrote a little over ten years later, Bouguer commented that his results had at least falsified the Hollow Earth Theory. In 1772, Nevil Maskelyne proposed to repeat the same experiment to the Royal Society. Within the same year, the Committee of Attraction was formed and they sent Charles Mason to find the perfect candidate for the vertical deflection experiment. Mason found the Schiehallion mountain, where the experiment took place and not only supported the earlier Chimborazo Experiment but yielded far greater results.

Contrary evidence
Seismic
The picture of the structure of the Earth that has been arrived at through the study of seismic waves[52] is quite different from a fully hollow Earth. The time it takes for seismic waves to travel through and around the Earth directly contradicts a fully hollow sphere. The evidence indicates the Earth is mostly filled with solid rock (mantle and crust), liquid nickel-iron alloy (outer core), and solid nickel-iron (inner core).[53]

Gravity
Main articles: Schiehallion experiment and Cavendish experiment
Another set of scientific arguments against a Hollow Earth or any hollow planet comes from gravity. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid spheroid is the best way in which to minimize the gravitational potential energy of a rotating physical object; having hollowness is unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve hydrostatic equilibrium with its own mass and would collapse.

Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm3, and typical densities of surface rocks are only half that (about 2.75 g/cm3). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13 g/cm3, which brings the average density of Earth to its observed value.

Direct observation
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the Kola Superdeep Borehole,[54] with a true vertical drill-depth of more than 7.5 miles (12 kilometers). However, the distance to the center of the Earth is nearly 4,000 miles (6,400 kilometers). Oil wells with longer depths are not vertical wells; the total depths quoted are measured depth (MD) or equivalently, along-hole depth (AHD) as these wells are deviated to horizontal. Their true vertical depth (TVD) is typically less than 2.5 miles (4 kilometers).

In fiction
Main article: Subterranean fiction
The idea of a hollow Earth is a common element of fiction, appearing as early as Ludvig Holberg's 1741 novel (Niels Klim's Underground Travels), in which Nicolai Klim falls through a cave while spelunking and spends several years living on a smaller globe both within and the inside of the outer shell.

Other notable early examples include Giacomo Casanova's 1788 , a 5-volume, 1,800-page story of a brother and sister who fall into the Earth and discover the subterranean utopia of the Mégamicres, a race of multicolored, hermaphroditic dwarves; published anonymously in 1819; by a "Captain Adam Seaborn" (1820) which reflected the ideas of John Cleves Symmes, Jr.; Edgar Allan Poe's 1838 novel Jules Verne's 1864 novel which showed a subterranean world teeming with prehistoric life; George Sand's 1864 novel where giant crystals could be found in the interior of the Earth; , an 1895 science-fiction allegory with major subterranean themes; and , a 1908 novel that included the idea that the North Pole was the entrance to the hollow planet.

In William Henry Hudson's 1887 romance, , the protagonist falls down a hill into a Utopian paradise; since he falls into this world, it is sometimes classified as a hollow Earth story; although the hero himself thinks he may have traveled forward in time by millennia.

The idea was used by Edgar Rice Burroughs in the seven-novel "Pellucidar" series, beginning with (1914). Using a mechanical drill, called the Iron Mole, his heroes David Innes and Professor Abner Perry discover a prehistoric world called Pellucidar, 500 miles below the surface, that is lit by a constant noonday inner sun. They find prehistoric people, dinosaurs, prehistoric mammals and the Mahar, who evolved from pterosaurs. The series ran for six more books, ending with (1963).[55] The 1915 novel by Vladimir Obruchev uses the concept of the Hollow Earth to take the reader through various geological epochs.

In recent decades, the idea has become a staple of the science fiction and adventure genres across films ( and the MonsterVerse), television programs (the third and fourth seasons of ), role-playing games (e.g., the Hollow World Campaign Set for , ), and video games ( and ).

In popular art
In 1975 Japanese artist Tadanori Yokoo used elements of the Aghartha legend, along with other Eastern subterranean myths, to depict an advanced civilization in the cover art for jazz musician Miles Davis's album .[56] Tadanori said he was partly inspired by his reading of Raymond W. Bernard's 1969 book .[57]

See also
Brinsley Le Poer Trench, 8th Earl of Clancarty - 1974 proponent of Hollow Earth
Dyson sphere
Expanding Earth
Flat Earth
Hades
Hollow Moon
List of topics characterized as pseudoscience
Scientific skepticism
Shamballa
Shellworld
Travel to the Earth's center
Xibalba
References
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John A MacCulloch, Celtic Mythology, Rowman & Littlefield Pub Inc, 1932, pp. 125–26
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Harold Bayley, Archaic England: An Essay in Deciphering Prehistory from Megalithic Monuments, 1919 Online Edition: Link
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George, Wally – Pilgrimage To The Devil., Article in Fate magazine, Aug. 1957, pp. 38–52
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Ferdynand Ossendowski (1922). Beasts, Men and Gods. New York: E. P. Dutton & Company.
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David Hatcher Childress Adventures Unlimited Press, 1998 ISBN 978-0932813633
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The Under-People, Eric Norman, Award Books, 1969
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(Oct. 1981 and Feb. 1982).
(1992), Martin Gardner, pp. 18–19
On the Wild Side, 1992, Martin Gardner.
Press, Frank; Siever, Raymond; Grotzinger, John; Jordan, Tom (2003). (4 ed.). New York, New York: W. H. Freeman. pp. 484–87. ISBN 978-0-7167-9617-6.
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External links