The Hollow Earth Theory

Throughout history there have been a number of different beliefs that the Earth might be hollow.

by Brian Dunning

Filed under Conspiracies, History & Pseudohistory, Religion

Skeptoid #343
January 1, 2013
Podcast transcript | Listen | Subscribe
Also available in Russian

Today we're going to point the skeptical eye at yet another alternative science that has managed to hang around for centuries despite being obviously wrong, the hollow Earth. There are many different models of hollow Earth theory, and support from equally diverse communities. It is a mind-bending example of how people can mold their world views to fit their beliefs, and then mold science itself to fit the world view.

Today, the prevailing hollow Earth theory states that the Earth is a hollow shell, with its inner surface being much like the outer surface where we live. It has oceans, mountain ranges, and clouds; and hovering at the very center of this hollow ball is a miniature sun that warms the inner-surface residents. Slightly offset from the North Pole and the South Pole are holes that allow travel between the outer and inner worlds. The civilization that lives on the inner surface is more advanced than ours, and they fly in and out through the polar openings in flying saucers, which explains UFO sightings by the outer surface civilization. Only the government knows about the polar openings and the inner civilization, and they suppress this information; ostensibly to prevent other governments from finding out about it and claiming the territory.

To most of us, this sounds like a pretty far-out concept; so many applications of various sciences prove it wrong. Nevertheless, even today, it has its supporters. Many books are available earnestly promoting the theory. Websites such as,, and provide only a starting point for active communities who firmly believe this.

Conspiracy mongering is a big part of most of today's hollow Earth writings: familiar assertions that the government is covering it up, the proverbial "they" don't want you to know about it, and that we should all "wake up" and see the truth. But this is the least interesting part of hollow Earth theory, and only its most recently introduced aspect. There is a rich and surprising history behind how this all came to be; a journey that began with scientific inquiry, but then went through philosophy, the comfort of knowing the universe was small and comprehensible, and religious zealotry.

In the late 1600s, Isaac Newton had been active for some time and a lot was already known about the Earth and its place in the cosmos. Although science had very good measurements, underlying theory in many areas was incomplete. For example, we knew that the magnetic pole had shifted over the centuries, but there was not yet a sound consensus on what made it do so. We knew about the aurora, but knew little about its cause. Astronomer Edmond Halley, after whom the famous comet was named when he calculated its orbit, presented his theories on both of these matters to the Royal Society.

Halley proposed that ferrous matter constituting the magnetic pole may have been movable because it was not attached to the Earth's surface, but was instead embedded in a freely-floating sub-sphere inside that upon which we live. He suggested that there were as many as three such layers around a solid core, all gravitationally centered, and all separated by atmospheres. He suggested that the aurora could be caused by luminous gases leaking out of a polar opening. Newton had already shown that the Earth was an oblate spheroid, thickest at the equator. This made sense to Halley, who figured that the outer crust was therefore thicker at the equator to account for the oblation and thinner at the poles; so thin that there could have been permeability for his luminous gases. He also reasoned that if there was light and an atmosphere between each layer, each might well be inhabited.

Another name from science has frequently been associated with the hollow Earth, that of Swiss mathematician and physicist Leonhard Euler, perhaps the most important and prolific mathematician of the 1700s. In one of his books, he discussed what would happen if you drilled a hole all the way through the Earth and dropped a stone through it. Apparently, despite much namedropping by various hollow Earth authors, this one statement was the closest Euler ever came to endorsing their theory. It appears that Euler's association with hollow Earthers is completely misinterpreted and made up; there's no evidence that he was a believer. Moreover, he openly criticized Halley's idea of concentric shells in a later volume of the same book.

It was Cyrus Teed, an American alchemist and pagan healer, who first proposed a different Earth model, based on what he described as a spiritual illumination from the Divine Motherhood. In Teed's view, the universe was inside out. The Earth was a sphere, but inside-out. The sun, moon, and all celestial phenomena are contained within, and we all live upon a concave surface that matches precisely the distances and directions of the conventional Earth model. We are all, according to Teed, living inside an isolated enclosed hollow cell in a universe of solid rock. Teed established the Koreshan Unity, a sort of commune church where celibacy was practiced and hollow Earthism was the philosophy. In a book published in 1870, The Cellular Cosmogony, or the Earth a Concave Sphere, Teed described his own theories of light, gravity, and many other sciences to fit his proposed model.

Perhaps the greatest story from the annals of hollow Earth theory was launched in 1897 by Ulysses Grant Morrow, a member of Teed's Koreshan Unity, and a fellow believer in the inside-out universe theory. Morrow had made numerous sightings at water level and verified the visibility of objects that should have been below the horizon, given a globe-shaped Earth; but he found that scientists dismissed his results because they could have been accounted for by simple atmospheric distortion, as is common at sea. Morrow contrived an experiment that he felt nobody could argue with: the construction of an absolutely straight reference line, four miles long, over water. If the inside-out theory was correct, Morrow's construction would be close to the water surface at its ends and high off the water at its middle. He went to work.

What he ended up with was a set of four "rectilinears", 12-foot-long and 4-foot-wide mahogany and brass rectangles, specially and carefully constructed by the Pullman railroad car company. The rectilinears were shaped like the letter H, diagonally cross braced with steel bars for rigidity. They were designed to bolt securely to one another with absolute precision, and extend a perfectly straight line. It wasn't practical to build four miles of rectilinears, so Morrow planned to start with one that was absolutely level, and then extend the line, leap-frogging each rectilinear from the back of the line to the front as each was secured in place. Each piece would be inverted when it was moved, to cancel out any possible asymmetries in the construction of each. If the Earth's surface were indeed curved, either concave or convex, the distance between the rectilinear and the mean water level would change slowly at first as the line extended, and the error would increase they further they went, as the curve grew steeper. The mean water level was determined using caissons along the route, at which tides were measured and corrected for.

The first rectilinear was positioned on March 18, 1897, solidly held on two securely anchored standards, and exhaustively leveled using two calibrated levels and a plumb bob. Morrow's team proceeded slowly and deliberately, spending nearly two months to traverse the four miles. Data was carefully measured and recorded the whole way, by multiple independent teams, with every number double checked and initialed. The results? Exactly as Morrow had expected, the data showed the Earth curving upward toward his rectilinears at a rate that consistent with a concave, hollow Earth with a radius of 4,050 miles (6,519 km). The Earth's actual radius is 3,963 miles (6,378 km). Morrow's measurement of the Earth's size was correct to 2.2% accuracy — but as a hollow, inside-out sphere on whose inner surface we live.

This was a huge confirmation for the Koreshan Unity Foundation. Modern analysis of their published data shows no methodological errors, and their experimental design was sound. How, then, can we account for their result?

The answer lies in the construction of the rectilinears. One survives today, on display at the Koreshan State Historic Site in Lee County, Florida. Although the rectangles were diagonally braced with steel rods to keep them precisely square, a critical attachment is missing. The steel rods were not connected to one another where they intersect, nor were they connected to the main structural cross bar. The intersection was freely floating. If there had been a connection, each rectilinear would have indeed been a rigid rectangle. Instead, this intersection was free to move up and down, allowing the structure to relax into a slight trapezoid. If supported by one end only — as each necessarily was when being bolted to its neighbor — it sagged, probably not enough to notice by eyeballing. Morrow assumed that inverting each segment each time it was reused would cancel out any irregularities. But this design failure meant that each section sagged downward regardless of which way it was oriented. As the Earth's surface curved downward away from Morrow's line, the line sagged downward twice as far, creating the illusion that the Earth was curving upward toward the line. That it happened to sag just enough to give an exactly opposite radius for the Earth appears to be just a coincidence.

The inside-out universe as a form of religious mysticism continued in Nazi Germany under the leadership of Luftwaffe pilot Peter Bender, who became head of the religious order; and whose work was continued by Karl Neupert, author of Geokosmos. A whole host of German authors continued this theme throughout the 1930s and 1940s.

But it was American John Symmes who was the earliest successful promoter of the model most popular today, that the Earth and universe are as we observe but that there is also a civilization living on the inner side of the Earth's crust. Symmes was actually close to getting the American government to sponsor an expedition to find the north polar opening, but when President Andrew Jackson took office in 1829, the plan died.

Tip Skeptoid $2/mo $5/mo $10/mo One time

And while the inside-out universe theory has withered away, the inner- and outer-world model has comparatively flourished. Gone are the colorations of early scientific inquiry and religious mysticism, and in their place is simple conspiracy mongering. Recent authors, such as Raymond Bernard in The Hollow Earth: The Greatest Discovery in History claim that many of the great early polar explorers were actually on secret missions to discover the polar openings and contact the inner-surface civilization. South African author Jan Lamprecht suggests that all the rocky planets in the solar system are constructed this way. Some of his evidence of a secret polar opening includes the fact that animals migrate seasonally, and where else would they be going; and the fact that early maps of the northern regions would be changed over the centuries, consistent with official coverups.

Whatever model they espouse, hollow Earth theories represent a fascinating look into the culture of the time. Whether it was Halley's genuine scientific curiosity, Teed's and Bender's counterculture religious beliefs, or modern anti-establishment conspiracy theories, we find that the hollow Earth is not so hollow after all; but is pregnant with sociological insight. The riches of any urban legend are found only when you dig past the legend itself.

Brian Dunning

© 2013 Skeptoid Media Copyright information

References & Further Reading

Gardner, M. "Notes of a fringe-watcher: Occam's razor and the nutshell earth." Skeptical Inquirer. 1 Jul. 1988, Volume 12, Number 4: 355-358.

Halley, E. "An account of the cause of the change of the variation of the magnetical needle with an hypothesis of the structure of the internal parts of the Earth: as it was proposed to the Royal Society in one of their later meetings." Philosophical Transactions of the Royal Society of London. 1 Jan. 1692, Number 17: 563-578.

Ohnemus, C. "Dr. Cyrus Teed and the Koreshan Unity Movement." Cultural Resource Management. 1 Jan. 2001, Volume 24, Number 9: 10-12.

Schadewald, R. "He knew Earth is round, but his proof fell flat." Smithsonian. 1 Apr. 1978, Volume 9, Number 1: 101-113.

Simanek, D. "Turning the Universe Inside-Out." Myths and Mysteries of Science. Lock Haven University, 22 Sep. 2003. Web. 21 Dec. 2012. <>

Teed, C. The Cellular Cosmogony, or The Earth a Concave Sphere. Chicago: The Guiding Star Publishing House, 1898.

Reference this article:
Dunning, B. "The Hollow Earth Theory." Skeptoid Podcast. Skeptoid Media, 1 Jan 2013. Web. 31 Aug 2015. <>


10 most recent comments | Show all 161 comments

The only unbelievable thing is the bad spelling in some of the posts.

joe, dban
November 25, 2013 2:22am


Joe falls into the usual category of grammar police.

Congrats if posts were english assignments and you (and others like you) are teachers then your spot on in your comments.

But given that you choose to point out grammar (which NO ONE is immune from mistakes) instead of debating the topic at hand then your post is pointless.

Or worse some (not sure if it applies to you) use it as an argument to defend your point instead of debating like an adult on topic. Which is quite sad and shows you cannot defend your position.

So other than that I can only take it that you either cannot defend your position (what is it?) on this topic, debate someone else's facts or opinions; or your just a grammar lover.

On the last go to something like msn comment section.
You should be in heaven.

Eric, Northern IL USA
November 30, 2013 3:13am


December 6, 2013 11:35am

I think that Eric is referring to Francesco Redi (the father of modern parasitology) and his flies and meat experiments of 1668, rather than Louis Pasteur 200 years later.

Eric also incorrectly uses the word "theory" when in actuality he's referring to hypotheses. The hollow earth idea is only a hypothesis—a vastly different thing.

A theory is supported with both empirical evidence and by peer review. A hypothesis has neither.

ausGeoff, Victoria, Australia
December 11, 2013 1:40pm

Sigh ausGeoff another scientific person who chooses to IGNORE the actual definition and supplant his own because it does not support his view of something.

Here is merriam-webster definition(s)

the·o·ry noun \ˈth"-ə-r", ˈthir-"\
: an idea or set of ideas that is intended to explain facts or events

: an idea that is suggested or presented as possibly true but that is not known or proven to be true

and more specific to topic definition by same source

a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena <the wave theory of light>

Note in all definitions listed it does not say in ANY WAY PROVEN.

Hence the term THEORY not FACT.

fact noun \ˈfakt\
: something that truly exists or happens : something that has actual existence

: a true piece of information

Back to the point I keep making until you drill a shaft to the center of the earth and take samples that can be TESTED and CONFIRMED as to what the makeup is and map under the earth all the way to the core all you have is a THEORY not proof.

Sigh again I am not saying the earth is like a sci fi disen sphere but for intelectual and scientific HONESTY stop saying a theory is a FACT.

The definitions do NOT support this IMO scientific laziness (at best) to outright dishonesty (at worst).

Eric, Northern IL USA
March 4, 2014 12:28am

Eric, I am a mere Geography scholl teacher, but, please, take my word that there is a verifiable proof of the current model (dense core and viscous mantle) of Earth internal structure.

The proof is ... earthquakes and seismographers.

Pinpointing the exact location, and time, of the earthquake, knowing the velocities that vibrations travels in different mediums, and acounting for echoes and changes on the pitch, geologists can use the signals received by a large number o seismographs scatered around the globe to probe the Earth like a doctor uses an ultrasonography device to know the sex of a yet-to-born baby.

All the readings point to a small ultra-dense area at the center enveloped by a dense zone.

Marcos Dantas, Rio de Janeiro, RJ, Brazil
March 6, 2014 8:58am

Ok marcus I will take you at your word your a geography teacher.

However your not a tech in the hardware of seismographs or ultrasound or are willfully ignorant of their limitations.

First seismographs ONLY detect sound waves/vibrations. They cannot tell you what causes them anymore than me seeing vibrations in (ex) a cup of milk can tell me if its a earthquake, truck passing by or a t-rex walking by (aka jurassic park movie).

Yes we know of earthquakes. But the limitations are we track them to fault lines that (while deep) are NO WHERE NEAR the center of the earth.

Second ultra sound probes of the earth have a limited range and have (to date) NEVER DIRECTLY MADE IT TO THE CENTER OF THE EARTH.

Yes you have some proof to support the current models (theories by another name) but again no DIRECT PROOF of what the center is.

I can show (ex) models based on some facts they use to predict hurricanes. But they have been WRONG 5+ YEARS running in their predictions.

Now in the news scientists by a diamond have found proof of large amount of water near the core that WAS NOT PREVIOUSLY KNOWN or even suspected.

Again back to my origional point everyone wants to ignore/belittle.

I dont know what the core is.

But the very definition of theory vs fact shows you need VERIFIABLE PROOF for one to become another.

Otherwise even in your textbooks they say the compositon of the earths core is A THEORY?

Eric, Northern IL USA
March 14, 2014 12:57am

He is correct. there is no proof of a core beyond speculation. Nor is there proof beyond speculation that is core is 6000C. Nor is there proof the mantle against a core is 3.3 atmospheres of pressure (beyond extrapolation, speculation). We have never dug down beyond 12,000km, all of science was wrong about what was below us, found on on this dig.

Not only, but you are to believe a pseudo, fictitious force, called coriolis, is responsible for spinning around a molten iron core, which creates magnetism by truly flipping science on it's head and removing the curie point of iron, proven to lose it's magnetic abilities at 700C.

seismic data works hollow model or solid model.

using SIMANEK's work of a speculative argument of sagging is not going to cut it here.. try retesting the rectilineator with today's capabilities.

Watch this "A line has been Drawn - the rectilineator documentary"

Learn something here.. Retest before you spit some other stupid argument/post.

Darkshark, Florida
July 27, 2015 5:31pm

You should contact me. I will correct everything in these posts and comments.


"A line has been drawn - The rectilineator documentary"

Darkshark, Florida
July 27, 2015 5:34pm


Just a small correction "We have never dug down beyond 12,000km,"

That figure should be 12,000 meters, and it's a little further that the deepest holes have been drilled, a couple of hundred meters, that's all.

Not even half-way through the Earth's crust. Barely scraping the skin of the planet.

Even then, there were "unexpected" discoveries etc which puts the center of the Earth, some 6300 kilometers away, nothing but theory and speculation.

With spacecraft now beginning to leave the solar system decades after they were launched, Pluto and Charon just recently flown by for the first time in NASA history, the center of the Earth in fact, so near and yet so far, is beyond our capability to reach anywhere near it.

Even the deepest earthquakes are only 10% of said depth.

Macky, Auckland
July 27, 2015 10:05pm

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