Hollow Earth hypothesis

This idea is really extreme. Apparently, there is a belief that the Earth is hollow and there is a large interior space inside it. This 'Inner Earth' is the basis for mythology, folklore and legends, not to mention, a lot of classic fantasy stories.

This idea is basically pseudoscience, but it's not as bad as the idea that the Earth is flat. It's hard to imagine that there are people who actually believe that the Earth is flat.

The idea that the Earth is hollow has a long history. Many cultures believed that there was an underworld where souls went after death. Some believed that gods ruled the underworld. All ancient peoples had mythology or religions based on the idea that that there was a large hollow cavern or space where their ancestors went. I can understand why this belief was prominent. Ancient people had no concept of geology. They had no idea what really existed below them, so they made up ideas to fit their religions.

In 1692 Edmond Halley proposed that the Earth had two inner concentric shells and an innermost core. These shells rotated independently at different speeds and they had their own magnetic poles. He did this to explain anomalous compass readings. This wouldn't have been so bad, but he also proposed that these inner shells had atmospheres and were inhabited by mysterious people.

Leonhard Euler changed Halley's ideas by eliminating the inner shells and substituting an inner sun to provide light to the civilization that lived on the inner Earth.

The hollow Earth concept persisted into the 19th century (1818) when John Cleves Symmes Jr. proposed a hollow shell about 1000 kilometers thick and proposed an expedition to the North Pole to find an entrance into this inner world. President John Quincy Adams said he would approve it but it never happened because president Andrew Jackson nixed it. Symmes' son published a book about his father's ideas, 'Theory of Concentric Spheres', in 1878.

By the 20th century, this hollow Earth idea was incorporated into the New Age ideas that became popular by then. Pulp science fiction authors who often combined it with UFO and ancient alien beliefs exploited the concept. One theory is that the ancient Atlantis inhabitants took refuge in the inner Earth before their city was destroyed.
First of all, there is no way that such a complicated Earth model could work. When the Earth was formed from a dust and rock cloud, gravity would have smashed everything together and then compressed it. There would be no way that a shell inside could have survived. Besides, seismic waves would end up having strange blips in which the sound would go faster in air that would have to exist in the hollow part of the Earth. This is not what seismologists see.

Astrophysicists can calculate what the density of the Earth should be from its orbital motions around the Sun and the interactions with the Moon. This calculation of mass would lead to a density that would be inconsistent with a hollow Earth.

There is no evidence from deep oil drilling to indicate that a hollow Earth exists.

It does make for some interesting fiction, but that's as good as it gets.

Thanks for reading.