Hollow Earth Shenanigans

Hollow Earth Theory


Well hello there passengers, and welcome to yet another exciting day aboard the MidnightTrain. Today we delve deep into the mysterious, creepy, possibly conspiratorial world that is our own. What do I mean by that? Well we are digging our way to the center of truth! Today, we learn about Hollow Earth… and for the flat earthers out there… you’re gonna wanna hang out for a minute before you dip outta here… also fuck you.


(Cinematic trailer voice) In a World where there exists people who think the world is a flat piece of paper with trees growing out of it and a big guy who flips the piece of paper over to switch between day and night. One man wants to change that idea. His name… is Edmund Halley. Yes that Halley. The one known for the comet he discovered. But before we explore more about him and his findings, let's discuss what led us to this revolutionary hypothesis.


So besides idiots who believe the earth is flat, I mean stupid-endous personalities, there are other more interesting characters that believe the earth is completely hollow; or at least a large part of it. This is what we call the Hollow Earth Theory. Now where did this all come from? Well, nobody cares, Moody. That's the show folks!


Ok, ok, ok… fine. Since the early times many cultures, religions, and folklore believed that there was something below our feet. Whether it’s the lovely and tropical Christian Hell, the Jungle-esque Greek Underworld, the balmy Nordic Svartálfaheim, or the temperate Jewish Sheol; there is a name for one simple idea. These cultures believed it to be where we either come from or where we go when we die. This may hold some truth, or not. Guess we will know more when the time comes.


The idea of a subterranean realm is also mentioned in Tibetan Buddhist belief. According to one story from Tibetan Buddhist tradition, there is an ancient city called Shamballa which is located inside the Earth.

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. In Thracian and Dacian legends, it is said that there are caverns occupied by an ancient god called Zalmoxis. In Mesopotamian religion there is a story of a man who, after traveling through the darkness of a tunnel in the mountain of "Mashu", entered a subterranean garden. Sounds lovely.

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.​​ They are said to be bald, taller than most with blue eyes and a big, bushy beard… fucking Moody. 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. You guys know purgatory, that place or state of suffering inhabited by the souls of sinners who are shedding their sins before going to heaven. In County Down, Northern Ireland there is a myth which says tunnels lead to the land of the subterranean Tuatha Dé Danann, who are supposedly a group of people who are believed to have introduced Druidism to Ireland, and then they said fuck it and went back underground.

In Hindu mythology, the underworld is referred to as Patala. In the Bengali version of the Hindu epic Ramayana, it has been depicted how Rama and Lakshmana were taken by the king of the underworld Ahiravan, brother of the demon king Ravana. Later on they were rescued by Hanuman. Got all that?

The Angami Naga tribes of India claim that their ancestors emerged in ancient times from a subterranean land inside the Earth. The Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground.

Natives of the Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula". Mexican folklore also tells of a cave in a mountain five miles south of Ojinaga, and that Mexico is possessed by devilish creatures who came from inside the Earth. Maybe THAT’S where the Chupacabra came from!

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. Luckily, they had plenty of space rope to make it back out. The Italian writer Dante describes a hollow earth in his well-known 14th-century work Inferno, in which the fall of Lucifer from heaven caused an enormous funnel to appear in a previously solid and spherical earth, as well as an enormous mountain opposite it, "Purgatory". There’s that place, again.

In Native American mythology, they believed 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. There is also a tale about a tunnel in the San Carlos Apache Indian Reservation in Arizona near Cedar Creek which is said to lead inside the Earth to a land inhabited by a mysterious tribe. It is also the belief of the tribes of the Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth. The elders of the Hopi people believe that a Sipapu entrance in the Grand Canyon exists which leads to the underworld.

Brazilian Indians, who live alongside the Parima River in Brazil, claim that their forefathers emerged in ancient times from an underground land, and that many of their ancestors still remained inside the Earth. Ancestors of the Inca supposedly came from caves which are located east of Cuzco, Peru. So, this is something that has been floating around a shit ton of ancient mythos for a long ass time. Well, ya know… before that silly thing called SCIENCE. Moving on.



Now to circle back to our friend Edmund. He was born in 1656, in Haggerston in Middlesex (not to be confused with uppersex or its ill-informed cousin the powerbottomsex). He was an English astronomer, geophysicist, mathematician, meteorologist, and physicist; because what else was there to do in the 1600’s but be a know-it-all? He was known to work with Sir Isaac Newton among other notable (but not gonna note them here) proponents to science.



In 1692 he proffered the idea that the earth was indeed hollow and had a shell about 500 miles thick with two inner concentric (having a common center, as circles or spheres… hear that flat earthers??) shells and an inner core. He proposed that the atmospheres separated the shells and that they also had their own magnetic poles and that the shells moved at different speeds. This idea was used to elucidate(shed light upon… yes pun intended) anomalous(ih-nom-uh-luhs) compass readings. He conceptualized that the inner region had its own atmosphere and possibly luminous with plausible inhabitants. MOLE PEOPLE!! He also thought that escaping gases from the inner earth caused what is now known as the Northern Lights.


Now another early ambassador to this idea was Le Clerc Milfort. Jean-Antoine Le Clerc, or known by a simpler name, Louis Milfort. Monsieur Milfort was a higher ranking French military officer who offered his services during the late 1700’s. He is most notably known for leading Creek Indian warriors during the American Revolutionary War as allies of the British. I guess having a common enemy here would make sense as to why he chose this group to lead. He emigrated in 1775 to what was then known as the British Colonies of North America. But we all know there is nothing Bri’ish about us.


Now why would a higher ranking French military Officer want to emigrate from his home to a place of turmoil? Great question Moody! I knew you were paying attention. Well, a little about this French saboteur.


He was known by many aliases, but we will just stick with Louis (Louie) for all intents and purposes. Louis was born in Thin-le-Moutier, near Mezieres, France. He served in the French Military from 1764 to 1774. Now this is according to his memoir that was dated in 1802. He left France after he ended up killing a servant of the king’s household in a duel. Apparently, the king’s servant loved the king. So much so that when Louis read aloud a poem that he had written that included the king, the servant jumped up, tore off his glove and slapped Louis across the face not once, but 4 fucking times! This is obviously something that Louis could not just let happen, so he challenged the servant to a duel. Not just any duel, mind you. He challenged him to a duel of what was then known as a “mort de coupes de papier.” The servant died an excruciating death and Louis fled. Here is the poem that started the feud.

There’s a place in France

Where the naked ladies dance

There’s a hole in the wall

Where the men can see it all

But the men don’t care

Cause they lost their underwear

And the cops never shoot

Cause they think it’s kind of cute

There a place in France

Where the alligators dance

If you give them a glance

They could bite you in the pants

There’s a place on Mars

Where the ladies smoke cigars

Every puff she makes

Is enough to kill the snakes

When the snakes all die

They put diamonds in their eye

When the diamonds break

The dancing makes them ache

When the diamonds shine

They really look so fine

The king and the queen

Have a rubber ding-a-ling

All the girls in France

Have ants in their pants



Yes, this is 100% bullshit… but, you’ll have that shit stuck in your head for days.

Now as much as we tried to find ACTUAL information as to why there was duel and why it was with a servant of the king, we couldn't find much. But after digging up some more information on Louis we found out that he ended up going back to France to be a part of the Sacred Society of Sophisians.


This group is also known as the secret society of Napoleon's Sorcerers… This may have to be a bonus episode so stay tuned for more!


Now back to the “Core” of our episode. The Creek Indians who are originally from the Muscogee [məskóɡəlɡi](Thank wikipedia) area which is southeast united states which roughly translates to the areas around Tennessee, Alabama, western Georgia and Northern Florida. Louis adapted their customs and assimilated into their Tribe. He even married the sister of the Chief.


Now after Louis and the rest of the people in the American Revolutionary War lost to the U.S. he decided to lead the Creek Tribe on an expedition in 1781 because, well, they had nothing else to do. On this expedition they were searching for caverns where allegedly the Creek Indians ancestors had emerged from. Maybe even the Origin of Bigfoot.


Yes, the Creek Indians had believed that their ancestors lived below the earth and lived in caverns along the Red River junction of the Mississippi River. Now during the expedition they did come across these caverns which they suspected could hold 20,000 of their family in. That's pretty much all they found. They didn't have video cameras back then otherwise, I'm pretty sure they would have found footage of bigfoot though.


Another advocate was Leonhard Euler, yes, you heard right. Buehler… Buehler… No Leonard Euler. A great 18th century mathematician; or not so great if you didn't enjoy math in school unlike moody who was the biggest nerd when it came to math.


Euler founded the study of graph theory and topology. No moody, not on-top-ology. Mind always in the gutter. Euler influenced many other discoveries such as analytic number theory, complex analysis, and the coolest subject ever; Infinitesimal Calculus. Which is Latin for BULLSHIT.


But anyways I digress. This guy knew his stuff BUT he did think with all his “infinite” wisdom that the earth was in fact hollow and had no inner shells but instead had a six hundred mile diameter sun in the center. The most intriguing and plausible theory he had within this whole idea was that you could enter into this interior from the northern and southern poles. Let’s hold to that cool hypothesis for right now and move along with our next Interesting goon of the hollow earth community.


With Halley’s spheres and Eulers’s Holes came another great man with another great theory. Captain John Symmes! Yes you know Captain Symmes. HE was a hero in the war of 1812 after being sent with his Regiment to Canada and providing relief to American forces at the battle of Lundy’s Lane. He was well known as a trader and lecturer after he left the army.


In 1818 Symmes announced his theory on Hollow Earth to the World! With his publication of his Circular No. 1.


“I declare the earth is hollow, and habitable within; containing a number of solid concentric spheres, one within the other, and that it is open at the poles 12 or 16 degrees; I pledge my life in support of this truth, and am ready to explore the hollow, if the world will support and aid me in the undertaking.”— John Cleves Symmes Jr., Symmes' Circular No. 1

While there were few people who would consider Symmes as the “Newton of the West”, most of the world was less than impressed. Although his theory wasn't as popular as one would expect, you gotta admire the confidence he had.


Symmes sent this declaration at a rather hefty cost to himself to “each notable foreign government, reigning prince, legislature, city, college, and philosophical societies, throughout the union, and to individual members of our National Legislature, as far as the five hundred copies would go.”15]


Symmes would then be followed by an exorbitant amount of ridicule for his proclamation, as many intellectuals were back then. This ridicule would later influence a rather bold move, Cotton. We’ll touch on this later.


What was so special about his theory that got 98% of the world not on the edge of their seats? Well, to start he believed the Earth had five concentric spheres with where we live to be the largest of the spheres. He also believed that the crust was 1000 miles thick with an arctic opening about 4000 miles wide and an antarctic opening around 6000 miles wide.

He argued that because of the centrifugal force of the Earth’s rotation that the poles would be flattened which would cause such a gradual gradation that you would travel into the Hollow Earth without even knowing you even did it.


Eventually he refined his theory because of such ridicule and criticism. Now his theory consists of just a single hollow sphere instead of five concentric spheres. So, now that we know all about symmes and his theory, why don't we talk about what he decided to do with his theory?


What do you think, Moody? You think he created a cult so he could be ostracized? Or do you think he gave up and realized he was silly? Hate to be the bearer of bad news here but he decided to take his theory and convince the U.S. congress to fund and organize an expedition to the south pole to enter the inner earth.


Good news and bad news folks. Good news, congress back then actually had some people with heads on their shoulders as opposed to those today and they said fuck that noise and denied funding for his expedition. Hamilton, Ohio even has a monument to him and his ideas. Fuckin’ Ohio.

Next up on our list of “what the fuck were they thinking?” We have Jeremiah Reynolds. He also delivered lectures on the "Hollow Earth" and argued for an expedition. I guess back in those days people just up and went to the far reaches of the earth just to prove a point. Reynolds said “look what I can do” and 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 craziness, I MEAN “INTEREST”.

He gained support from marine and scientific societies and, in 1828, successfully lobbied the House of Representatives to pass a resolution asking then-President John Quincy Adams to deploy a research vessel to the Pacific.

The president, for his part, had first mentioned Reynolds in his November 4, 1826, diary entry, writing:

“Mr Reynolds is a man who has been lecturing about the Country, in support of Captain John Cleves Symmes’s theory that the Earth is a hollow Sphere, open at the Poles— His Lectures are said to have been well attended, and much approved as exhibitions of genius and of Science— But the Theory itself has been so much ridiculed, and is in truth so visionary, that Reynolds has now varied his purpose to the proposition of fitting out a voyage of circumnavigation to the Southern Ocean— He has obtained numerous signatures in Baltimore to a Memorial to Congress for this object, which he says will otherwise be very powerfully supported— It will however have no support in Congress. That day will come, but not yet nor in my time. May it be my fortune, and my praise to accelerate its approach.”

Adams’ words proved prophetic. Though his administration opted to fund Reynolds’ expedition, the voyage was waylaid by the 1828 presidential election, which found Adams roundly defeated by Andrew Jackson. The newly elected president canceled the expedition, leaving Reynolds to fund his trip through other sources. (The privately supported venture set sail in 1829 but ended in disaster, with the crew mutinying and leaving Reynolds’ ass on shore.) Per Boston 1775, the U.S. Exploring Expedition only received the green light under the country’s eighth president, Martin Van Buren.

As Howard Dorre explains on his Plodding Through the Presidents blog, multiple media outlets (including Smithsonian, in an earlier version of this article) erroneously interpreted Adams’ description of Reynolds’ ideas as “visionary” as a sign of his support for the hollow earth theory. In fact, notes Bell in a separate Boston 1775 blog post, the term’s connotations at the time were largely negative. In the words of 18th-century English writer Samuel Johnson, a visionary was “one whose imagination is disturbed.”

The president, adds Dorre, only agreed to support the polar expedition “after Reynolds abandoned the hollow earth idea.” I had always heard that he was a believer in mole people and hollow earth, turns out his words were just misinterpreted. Hmm… I wonder if there are any other books out there where the overall ideas and verbage could and have been misinterpreted causing insane amounts of disingenuous beliefs? Nah!


Though Symmes himself never wrote a book about his ideas, several authors published works discussing his ideas. McBride wrote Symmes' Theory of Concentric Spheres in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: Remarks of Symmes' Theory Which Appeared in the American Quarterly Review. In 1868, a professor W.F. Lyons published The Hollow Globe which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Because fuck that guy, right? Symmes's son Americus then published The Symmes' Theory of Concentric Spheres in 1878 to set the record straight. I think the duel would have been a better idea.

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

In 1864, in Journey to the Center of the Earth, Jules Verne described a hollow Earth containing two rotating binary stars, named Pluto and Proserpine. Ok… fiction. We get it.

William Fairfield Warren, in his book Paradise Found–The Cradle of the Human Race at the North Pole, (1885) presented his belief that humanity originated on a continent in the Arctic called Hyperborea. This influenced some early Hollow Earth proponents. According to Marshall Gardner, both the Eskimo and Mongolian peoples had come from the interior of the Earth through an entrance at the North Pole. I wonder if they knew that.


NEQUA or The Problem of the Ages, 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 Phantom of the Poles in 1906. He supported the idea of a hollow Earth, but without interior shells or inner sun. Ok, no sun. Got it.

The spiritualist writer Walburga, Lady Paget in her book Colloquies with an unseen friend (1907) was an early writer to mention the hollow Earth hypothesis. She claimed that cities exist beneath a desert, which is where the people of Atlantis moved. Mmmk. Deserts and Atlantis. Check. She said an entrance to the subterranean kingdom will be discovered in the 21st century. Pretty broad brush she’s painting with there.

Next up we're gonna talk a little about Admiral Richard E. Byrd. According to Hollow Earth theorists, Byrd met an ancient race underground in the South Pole. According to Byrd’s “diary,” the government ordered Byrd to remain silent for what he witnessed during his Arctic assignment:

March 11, 1947

“I have just attended a Staff Meeting at the Pentagon. I have stated fully my discovery and the message from the Master. All is duly recorded. The President has been advised. I am now detained for several hours (six hours, thirty- nine minutes, to be exact.) I am interviewed intently by Top Security Forces and a Medical Team. It was an ordeal!!!! I am placed under strict control via the National Security provisions of this United States of America. I am ORDERED TO REMAIN SILENT IN REGARD TO ALL THAT I HAVE LEARNED, ON THE BEHALF OF HUMANITY!!! Incredible! I am reminded that I am a Military Man and I must obey orders.”

After many polar accomplishments, Byrd organized Operation Highjump in 1947. The objective: construct an American training and research facility in the South Pole. Highjump was a significant illustration of the state of the world and the cold war thinking at the time. The nuclear age had just begun, and the real fears were that the Soviet Union would attack the United States over the North Pole. The Navy had done a training exercise there in the summer of 1946 and felt it needed to do more. The northern winter was coming, and Highjump was a quickly planned exercise to move the whole thing to the South Pole. Politically, the orders were that the Navy should do all it could to establish a basis for a [land] claim in Antarctica. That was classified at the time.Now Operation High jump could probably be its own episode, or is at minimum a bonus. But we'll get some of the important details on how it pertains to this episode. Some say the American government sent their troops to the South Pole for any evidence of the rumored German Base 211.

Nazis were fascinated with anything regarding the Aryan race. They traveled all over the world including Antarctica to learn more of alleged origins.

The Germans did make their mark in the South Pole. However, what they have discovered doesn’t compared to what Byrd recorded in his diary. the time. The nuclear age had just begun, and the real fears were that the Soviet Union would attack the United States over the North Pole. The Navy had done a training exerci but was that all it was


“For thousands of years, people all over the world have written legends about Agartha (sometimes called Agarta or Agarthi), the underground city. Agartha (sometimes Agartta, Agharti, Agarath, Agarta or Agarttha) is a legendary kingdom that is said to be located in the Earth's core. Agartha is frequently associated or confused with Shambhala which figures prominently in Vajrayana Buddhism and Tibetan Kalachakra teachings and revived in the West by Madame Blavatsky and the Theosophical Society. Theosophists in particular regard Agarthi as a vast complex of caves underneath Tibet inhabited by demi-gods, called asuras. Helena and Nicholas Roerich, whose teachings closely parallel theosophy, see Shambhala's existence as both spiritual and physical. Did Byrd find it?

He claims to have met “The Master,” the city’s leader, who told him of his concerns about the surface world:

“Our interest rightly begins just after your Race exploded the first atomic bombs over Hiroshima and Nagasaki, Japan. It was that alarming time we sent our flying machines, the ‘Flugelrads’ to your surface world to investigate what your Race had done…You see, we have never interfered before in your Race’s wars and barbarity. But now we must, for you have learned to tamper with a certain power that is not for your Man, mainly that of atomic energy. Our emissaries have already delivered messages to the power of your World, and yet they do not heed.”

Apparently, the government knew about Agartha before Byrd.

Marshall Gardner wrote A Journey to the Earth's Interior in 1913 and published an expanded edition in 1920. He placed an interior sun in the Earth (ah ha! The Sun’s back!) and built a working model of the Hollow Earth which he actually fucking patented (U.S. Patent 1,096,102). Gardner made no mention of Reed, but did criticize Symmes for his ideas. DUEL TIME! Around the same time, Vladimir Obruchev wrote a novel titled Plutonia, in which the Hollow Earth possessed an inner Sun and was inhabited by prehistoric species. The interior was connected with the surface by an opening in the Arctic.

The explorer Ferdynand Ossendowski wrote a book in 1922 titled Beasts, Men and Gods. Ossendowski said he was told about a subterranean kingdom that exists inside the Earth. It was known to Buddhists as Agharti.

George Papashvily in his Anything Can Happen (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. This dude was a sniper with the Imperial Russian Army during World War I

Moody is going to love these next examples.

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

According to the ancient astronaut writer Peter Kolosimo a robot was seen entering a tunnel below a monastery in Mongolia. Kolosimo also claimed a light was seen from underground in Azerbaijan. Kolosimo and other ancient astronaut writers such as Robert Charroux linked these activities to DUN DUN DUNNNN….UFOs.

A book by a "Dr. Raymond Bernard" which appeared in 1964, The Hollow Earth, 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. An article by Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's Subterranean Worlds: 100,000 Years of Dragons, Dwarfs, the Dead, Lost Races & UFOs from Inside the Earth did the full story of Bernard/Siegmeister become well-known. Holy fucking book title, Batman!


The science fiction pulp magazine Amazing Stories promoted one such idea from 1945 to 1949 as "The Shaver Mystery". The magazine's editor, Ray Palmer, ran a series of stories by Richard Sharpe Shaver, claiming that a superior pre-historic race had built a honeycomb of caves in the Earth, and that their degenerate descendants, known as "Dero", live there TO THIS DAY, 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 Lost Continents and the Hollow Earth(1998) in which he reprinted the stories of Palmer and defended the Hollow Earth idea based on alleged (cough… “alleged”) tunnel systems beneath South America and Central Asia.

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, Staffordshire in England, Montreal in Canada, Hangchow in China, and The Amazon Rain Forest.


Ok, have you two gents heard of the Concave Hollow Earth Theory?

It doesn’t matter, we’re still going to talk about this lunacy.

Instead of saying that humans live on the outside surface of a hollow planet—sometimes called a "convex" Hollow Earth hypothesis—some whackamuffins have claimed humans live on the inside 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". He might as well have called it Goobery Kabooblenuts. See, I can make up words, too. Anyway, Teed founded a group called the Koreshan Unity based on this notion, which he called Koreshanity. Which sounds like insanity and would make far more sense. The main colony survives as a preserved Florida state historic site, at Estero, Florida, but all of Teed's followers have now died. Probably from eating Tide Pods. 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. Which sounds like something you use to clean out your colon.


Several 20th-century German writers, including Peter Bender, Johannes Lang, Karl Neupert, and Fritz Braut, published works advocating the Hollow Earth hypothesis, or Hohlweltlehre. 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. Oh boy.

The Egyptian mathematician Mostafa “Admiral Akbar” Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model

In one chapter of his book On the Wild Side (1992), Martin Gardner discusses the Hollow Earth model articulated by Abdelkader. According to Gardner, this hypothesis posits that light rays travel in circular paths, and slow as they approach the center of the spherical star-filled cavern. No energy can reach the center of the cavern, 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. Christ, my head hurts.

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. Occam’s razor is the problem-solving principle that "entities should not be multiplied beyond necessity", sometimes inaccurately paraphrased as "the simplest explanation is usually the best one."

Purportedly verifiable hypotheses of a Concave Hollow Earth need to be distinguished from a thought experiment which defines a coordinate transformation such that the interior of the Earth becomes "exterior" and the exterior becomes "interior". (For example, in spherical coordinates, let radius r go to R2/r where R is the Earth's radius; see inversive geometry.) The transformation entails corresponding changes to the forms of physical laws. This is not a hypothesis but an illustration of the fact that any description of the physical world can be equivalently expressed in more than one way.


Contrary evidence


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