Hollow earth

The Hollow Earth hypothesis proposes that the planet Earth either is entirely hollow or otherwise contains a substantial interior space. The scientific community has dismissed the notion since at least the late 18th century. The concept of a hollow Earth recurs many times in folklore and as the premise for subterranean fiction, a subgenre of adventure fiction (A Journey to the Center of the Earth, At the Earth's Core). It is also featured in some present-day pseudoscientific and conspiracy theories.

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 Buddhism belief. According to one story, there is an ancient city called Shamballa which is located inside the Earth.

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 Trozien in Argolis, at Ephya in Thesprotia, at Herakleia in Pontos, and in Ermioni. In Thracian and Dacian legends, it is said that there are underground chambers occupied by an ancient God called Zalmoxis. In Mesopotamian religion there is a story of a man who, after traveling through the darkness of a tunnel in the mountain of "Mashu", entered a subterranean garden.

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