2. While many have approached this by providing various evidences of why the earth must be shaped like a globe, and not flat like a pancake as flat earth believers claim, I have not seen any debunkers that approach it this way - namely by looking at the physics of such a system as Albert Einstein might.

So for these reasons I throw my hat into the flat earth debunking ring. Since I am approaching this from the stand point of an investigation of the physics as Albert Einstein might investigate it, let me describe the approach he would probably take, and the primary theory we must understand.

Einstein's Experimental method: The Thought Experiment

Einstein's theories of Special Relativity and General Relativity deal with the nature of light and gravity in a manner that he could not - with the technology of the day - directly experiment with and observe.  That was no object to Einstein, because his main method of discovery was not through physical experimentation, but rather experiments run in his mind, what he called thought experiments. "It's what you and I would call 'daydreaming', but he gets to call them thought experiments because he's Einstein"[1] says one Einstein biographer.  For this examination of flat earth theory, we will take up Einstein's method of the thought experiment, and think through the consequences of physics if the earth were, as the flat earth adherents claim, flat, shaped like a pancake.

Before we do so we need to understand one of Einstein's greatest contributions to science. I'm not speaking of his equation E=mc²  , which showed the equivalence between energy and mass; rather I'm speaking about his General Theory of Relativity which is basically an entirely new concept of gravity. His new theory supplanted Isaac Newton's theory of gravity[2] as the correct way to view what we used to call the "gravitational pull."  I say "used to call" because according to Einstein, there is no such thing as a gravitational pull.  Rather, what we experience as "gravity" is really the push of the fabric of space-time which was been curved by the mass of a nearby object. Thus rather than the pull of gravity, we experience the push of space time. Physicist Michio Kaku put it this way:

"There is no such thing as gravitational pull. The earth has curved the space around me and space is pushing me into this chair. Space itself can be curved."[3]
Michio Kaku

Okay, so we've got our basic theory of gravity we're working with. Now, let's consider a model of the standard flat earth theory, which is depicted in this video:

Please take a few moments to view if not familiar with the flat earth model.  Got the picture? Okay, let's commence with our thought experiments, which will highlight a number of insurmountable problems for this flat earth model.

Flat Earth Problems

Problem 1:  Objects in orbit
Sun and Moon Orbital Problem
a) What makes the sun and moon orbit around the vertical axis?
Notice how the sun and moon are circling the earth.  According to both Einstein and Newton, the only way those objects could be circling the earth like that is if there were some massive body at the center of their orbit.  But a massive body is not visible on the vertical axis anywhere on the earth, and the flat earth model allows for no such massive body.  There's another problem even if the flat earth model did allow for such an object. Since the earth itself is not in orbit around the object, the earth would fall toward the object and crash into it. Yet it hasn't, likely because such an object doesn't exist.  But the non-existence of such an object is a death blow to the flat earth theory.

GPS Satellite Orbit Problem

b) What keeps satellites from falling into the gravitational groove at the edge?

The arrows in the picture above show conceptionally how gravity on a flat earth would be greatest around the edge of the earth and weakest at the center. This would create a gravitational  grove or rut of curved space around the flat disk of the earth that would cause all satellites to fall towards the arrows of greatest length (where gravity is greater) and thus eventually fall into the gravity groove at the edge.  Like the problem with the sun and moon, there is no massive object (like a large central sun; the flat earth sun is estimated to be only 32 miles in diameter, and it's not central or stationary) to keep satellites (especially geosynchronous ones) in orbit above the mass of the flat earth where people live. Thus all satellites would fall into the curved space gravitational groove around the earth created by the mass of the flat earth disk. Having GPS satellites fall into orbit around the edge of the flat earth would of course be very problematic for GPS and communication satellites - they would cease to work properly, becoming largely ineffective.

The "Firmament" to the rescue?

These problems are based on the flat earth model depicted in this video [4] where the Sun and moon are at an altitude of 3000 miles above the flat earth, and the star "dome" (the firmament apparently) is 100 miles above the Sun and Moon. I take this to mean the sun and moon are not a part of the firmament, and move within the bounds of the space inside the firmament. But some flat earth believers state that the sun and earth are embedded within the firmament, as in this video. [5]  Additionally, this video states "The heavenly bodies were placed inside this firmament." (@22:51) and clearly depicts the sun and moon embedded in the firmament. It then states "The firmament is inherently solid."[6]  If that is the case then, the Sun and Moon are held in place by the firmament, as are the stars; and the firmament becomes - at least according to the first video - at least 100 miles thick of solid material. (Which would make it difficult for rockets and space ships to get through, which is why most flat earth believers don't believe in space travel, but we'll come back to that.)

But there are problems with this model - where the sun and moon are part of the solid firmament - too. Let's look first at an objection that Einstein would likely have, then we'll take a look an the word "firmament" to see if flat earth believers are interpreting it correctly.

Problem 2: Where are all the Gravitational Waves?
Einstein's theory of gravity - General Relativity - predicts that moving objects create a ripple in space-time which move at the speed of light. He called such ripples  gravitational waves. Most gravitational waves are too small and minute to be detected. But large gravity waves can be detected by LIGO -the Laser Interferometer Gravitational-Wave Observatory operated by Caltech and MIT. LIGO consists of two L-shaped, gravity wave detectors - one at  Washington (LIGO Hanford), and one at Louisiana (LIGO Livingston) and the two work together in concert to provide a verified detection of gravitational waves. The most recent detection was on January 4th, 2017,  when the two LIGO detectors detected the gravitational wave generated by the merging of two black holes some 3 billion light years away.[7]

If LIGO can detect a gravitational wave made by a tiny, minute portion of the universe (2 black holes out of all of the stars and black holes in existence) that's 3 billion light years away, why isn't it detecting the gravitational wave generated by the rotation of the entire universe (all stars and all black holes) only 3,000 miles away? If, as the flat earth believers state, all the heavenly bodies are embedded in the firmament, and the firmament is rotating every 24 hours, and it's only 3,000 miles away, it should be generating such massive gravitational waves that LIGO is lit up all the time, 24/7. But that is not the case. The LIGO gravitational wave detections are few and far between. That alone sounds the death knell to the proposition that the sun, moon stars and all the other heavenly bodies are embedded in the "firmament" and rotating in a daily cycle 3,000 miles above a stationary earth.

So there are problems if the Sun and moon are not embedded in the firmament; and there are problems if they are embedded in the firmament. But where did flat earth believers get this idea of a "firmament" from? The idea comes from a misunderstanding of a Biblical text.

What is the "firmament"?

The idea for the firmament comes from the text of the Biblical creation account:

And God said, "Let there be an expanse between the waters to separate water from water."
Gen 1.6

The bolded word in the original Hebrew is  רקיע  ( rāqīă‛ - raqiya ) and is translated by the NIV (1973-1984) as "expanse" and by the KJV and NKJV as "firmament." (The current NIV translates it as "vault" which seems to lean toward a solid firmament.) "Expanse" points to something that is spread out and thus expansive, while "firmament" points to something that is solid - as the flat earth believers take it. But which one is it? The general rule for interpretation of the Bible is to let scripture interpret scripture. And we have a verse in scripture that speaks specifically of the act of creation that can clarify matters: Is 42.5.

Before we take a look at it, let me say a word about the difference in rhyming between English and Hebrew. In English when we rhyme, we use a repetition of the same sound. For example:

In this example I hope all can see
So there is no doubt and all can agree

Here there is a repetition of the "ee" sound in "see" an "agree". In Hebrew rhyming is done not through repetition of the sound in the words used, but rather in a repetition in the ideas. This is very fortunate for us because that means that unlike English, Hebrew rhyming can be detected even across languages - even when the language translated into uses words that don't rhyme. Here is an example of Hebrew rhyme from Psalm 1:

Blessed is the man who does not walk in the counsel of the wicked or stand in the way of sinners or sit in the seat of mockers.
Psalm 1.1

Notice the repetition of ideas here:

Blessed is the man who
does not walk in the counsel of the wicked
or stand in the way of sinners
or sit in the seat of mockers.

Notice how a posture verb (walk, stand, sit) is followed by a word that describes a sinful person (wicked, sinners, mockers).  The Hebrew rhyme is detectable even though the English words don't rhyme. 

Now let's look at the text we'll use to clarify Gen 1.6, which is Is 42.5:

This is what God the LORD says-- he who created the heavens and stretched them out, who spread out the earth and all that comes out of it, who gives breath to its people, and life to those who walk on it:
Is 42.5

There are a number of rhyming statements here, but lets focus in on the words in question which I've highlighted in yellow. (I'll just note in passing that the verb "created" used here is the same verb - ברא [ bārā’ - bara] used in Gen 1.1 - "In the beginning, God created," used here in participial form.) The word used for "stretched out" is the verb נטה (nātāh - natah)- to stretch out, to spread out. And what word is it rhyming with? That would be our old friend רקע  (rŏqă‛ - roqah) the participial form of the verb, which has the cognate noun  רקיע  ( rāqīă‛ - raqiya ) used in Gen 1.6. Recall raqiya could mean either an extended solid surface or a stretched out expanse, but the rhyming word - natah - means to stretch out. So the meaning of raqiya here, to complete the rhyme must also mean to stretch out, or expand.  And remember, this verse is paralleling the ideas in Gen 1.6. So the idea in Gen 1.6 is not the idea of a solid firmament. It must be the idea of a stretched out expanse. Cosmologist Russell Humphreys spoke about this stretching of the expanse in his recent visit to Creation in the 21st Century with David Rives.[8]  Thus at the end of the day, flat earth adherents have misinterpreted one of the basic texts used to support their theory.

Problem 3: The Missing Acceleration Object and Unexplained gravity

According to flat earth believers, there is no such thing as gravity. The following is from a flat earth site:

"According to Flat Earth Theory, gravity does not exist. Instead, there is a force that produces identical effects as observed from the surface of the earth. This force is known as "Universal Acceleration" (abbreviated as UA."[9]

So instead of gravity, flat earth believers believe that the pancake shaped earth is accelerating up at a constant rate that exactly matches what we measure to be the force of gravity.  The problem with this is that according to Einstein, objects are accelerated in space only because curved space is pushing them. And space is curved because there is a mass in space curving it. Therefore under flat earth theory, there must be a super huge, massive object curving space sufficiently to accelerate the earth and the firmament, which you'll remember includes all the stars and heavenly bodies, up at the precise rate of gravity as measured on earth.  There's two problems with this theory:

1. Flat earth theory cannot account for such an object - since all heavenly bodies are in the firmament. The only thing above the firmament are the waters above the sky (Gen 1.7, Ps 148.4). But the waters above the sky are understood to be resting upon the firmament; in fact the firmament is supposed to be keeping those waters out.  If you place a magnet on your refrigerator, it stops moving once it comes in contact with the refrigerator since there's no more distance to move through to reach it. Likewise if the waters above the sky are above resting upon the firmament, there is no space for the firmament to move through, so the waters would not be accelerating the firmament beneath it. Dark Energy has been proposed, but dark energy (if it exists)  doesn't accelerate masses, it thins out space.

2. Missing Gravitational waves. If the earth is being accelerated up at the speed of gravity, that means that the firmament is also being accelerated up - or we'd smash into it. Thus the entire universe (earth and firmament) must be accelerating up. That's a huge mass that's moving. According to Einstein, it must be producing massive gravitational waves in the fabric of space. Such waves move at the speed of light. Why has LIGO not detected the gravitational waves from the acceleration of the mass of the entire universe? A reasonable explanation would be because the described motion (accelerating upward at the speed of gravity) is not happening. Which would then mean flat earth theory has no explanation for what everyone on earth experiences as "gravity."

An Easy Myth Buster Experiment to Prove (or disprove) the flat earth

When the myth busters Adam Savage and Jamie Hyneman set out to prove that the NASA moon landings were not a hoax[10], one of the proofs they adduced was the reflection of a laser beam from retro-reflectors placed on the moon (which reflect light back at the source regardless of the angle). They went to the Apache Point Observatory Lunar Laser-ranging Operation observatory (APOLLO) where they saw the return from a Gigawatt laser pointed at the moon. The distance to the moon is about 240,000 miles. But the diameter of the earth, according to flat earth theory, is only 25,000 miles.  So the flat earth, from end to end, is roughly one tenth the distance of the accepted, standard distance to the moon. Therefore the myth busters, or anyone else, should be able to shine a laser beam from one end of the flat earth to the other, assuming they're high enough for the beam to go over the mountains. Many observatories are built upon mountains, so that shouldn't be an issue. So an easy proof for flat earth believers would be to shine a laser from one end of the earth to the other, and have it reflected back.  That cannot be done if the earth is a globe.  With today's technology, this seems to me to be an easy proof.

But getting access to an observatory may prove difficult. Here's an easier test. You don't really need to shine the light from one end of the earth to the other. To disprove a globe shaped earth, all you need to do is prove that light is visible past the supposed curvature of the earth. For instance you could go a tall building like the Willis (formerly Sears) Tower in Chicago, or the CN Tower in Toronto. Let's take the CN tower. Its observation deck height according to Google is 447 m or 1467 feet. Next you need to calculate the distance to the horizon - beyond which you cannot see due to the curvature of the earth. Luckily there's a site that will calculate that for you called Metabunk: https://www.metabunk.org/curve/. Just plug in your height, and it gives you the distance to the horizon, and even corrects for refraction by the atmosphere. For the CN tower, corrected for refraction, distance to the horizon is 50.66 miles. So if the earth is curved like a globe, you shouldn't see a light from the tower beyond 51 miles. On the other hand, if the earth is flat, you should easily see the light from a distance of say, 100 miles. With a laser pointer and a trip to the CN tower, that is an easily do-able test. Station an observer 100 miles from the tower, go to the observation deck of the CN tower, and shine your laser pointer in the direction of your observer. Figure out some Morse code like unique signal to make sure your observer correctly identifies the light from the tower and have at it. An easy test.

So the question becomes, why have none of them done that to end all doubt? Why instead do communication experts tell us that radio communications are limited in distance due to "line of sight transmission?" Meaning that due to the curvature of the earth, radio transmissions (all in the EM spectrum including light) can only be received for limited distances. The answer to that gets us to an area which is a departure from the workings of the theory, but worthy of mentioning in passing.

The Grand Conspiracy

Flat earth believers, must necessary believe there is a grand conspiracy[11] in order to explain much otherwise un-explainable phenomenon. Like space travel, which is impossible due to the firmament. Therefore NASA must be lying, and it's all a grand conspiracy. Due to the problems with the gravitational groove and satellites mentioned above, I still don't know how they explain how GPS devices work since the GPS satellites could not stay in orbit. (Much less get to their 12,500 mile orbital altitude past the 3,000 mile altitude of the solid firmament.)  But it's not just NASA, it's a myriad of things: Radio distance limitations due to the curvature of the earth must be a lie; the shape of Antarctica is a big secret. (They believe instead Antarctica, there's a 200' wall that surrounds the flat earth that keeps the oceans from falling off the edge.)  Photos from space - especially of the earth - Photoshopped. The Chinese space program, false. In fact, all NASA missions to outer space, (The Moon, Mars, Saturn, Pluto, etc.) are all hoaxes. All lies to support the grand  conspiracy.  So if you want to join the ranks of flat earth believers, then you must become, by definition, a conspiracy theorist. And you'll fit perfectly the profile I describe in Doubt the Bible? You might be a Conspiracy Theorist.
 

Final Thoughts

In passing, flat earth believers cannot claim to live on planet earth. They may live on earth, but earth would not be a planet. If earth is flat, it no longer fits the definition of a planet. According to the latest definition, a planet is;

"a celestial body that (a) is in orbit around the sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit."[12]

The flat earth view fails at a couple of points: the earth is not in orbit around the sun in the flat earth view; and it has not assumed a nearly round shape because there is no gravity.

If my exploration of Einstein inspired "thought experiments" have not persuaded  you that the earth cannot be flat, then by all means check out the resources below. One I think is particularly persuasive is the Flat Earth Debunk Visualization [13]. Here are some of the easy to remember, but decisive points made against a flat earth:

• No Sunrise/Sunsets: Do  you like sunrises or sunsets? Kiss them good bye with the flat earth model. At 3,000 miles above ground level, the sun will never be seen to be rising or setting over the horizon. Ditto for the moon.
• Always visible sun: If the earth is flat, the sun would be visible all the times, 24 hours a day. As noted above, it would never set behind the horizon.
• Daily lunar phases, not monthly: We'd see all phases of the moon every day. All of them - new moon, 1/4 moon, 1/2 moon, 3/4 moon, full moon and everything in between - every day, not monthly.

Obviously the items above are nothing like the world we observe. So if nothing else, this should serve to demonstrate that belief in a flat earth not only does not match the observable evidence, but it is also a detour off the scriptural path that leads you to a place that has nothing to do with the doctrine of Creation.

Duane Caldwell | posted 25 July, 2017
Follow @duanecaldwell
 

Notes  

1 Walter Isaacson, author "Einstein - His life and universe", ref from "Einstein" History Documentary, 2008
Back

2. No need to feel sorry for Sir Isaac, his theory of gravity - meaning the basic equations he derived - are still useful in the vast majority of cases where you don't have to deal with relativistic space-time adjustments:

"...since under weak gravity, which is the case in most regions of a galaxy, apart from maybe inside or near a supermassive black hole at the core of the galaxy under consideration, Einstein’s general relativity theory produces the same equations of motion as Newton’s law of gravitation."

John Hartnett, "Has the Dark Matter Mystery Been Solved?", Bible Science Forum, April 6, 2017,
https://biblescienceforum.com/2017/04/06/has-the-dark-matter-mystery-been-solved/
Back

3. Michio Kaku, ref. from. "Einstein" History Documentary, 2008
Back

4. Flat Earth Debunk Visualization, YouTube, posted Oct 8, 2015 by David Ridlen, https://www.youtube.com/watch?v=uexZbunD7Jg
Back

5. The Flat Earth Dome Firmament, YouTube, posted Sep 27, 2016 by Dorje Daka
https://www.youtube.com/watch?v=ntxsQyKE2_c @22:51
Back

6. The Flat Earth Dome Firmament, @23:32
Back

7. "LIGO Catches Its Third Gravitational Wave!", LIGO News Release, 6/1/2017, https://www.ligo.caltech.edu/news/ligo20170601
Back

8.  Creation in the 21st Century, episode “Starlight Time and Physics”, TBN broadcast 8/26/2016; archived here: http://creationinthe21stcentury.com/starlight-time-and-physics-with-david-rives-and-dr-russell-humphreys-on-tbn/
Back

9. "Universal Acceleration", The flat Earth Wiki of The Flat Earth Society, accessed 7/23/2017, https://wiki.tfes.org/Universal_Acceleration
Back

10.  Myth Busters, Episode “NASA Moon Landing Hoax”, Documentary/Reality-TV, 2008
Back

11. Flat earth believers do in fact acknowledge such a grand conspiracy.
See for example: "The Conspiracy", The flat Earth Wiki,The Flat Earth Society, accessed 7/23/2017,
https://wiki.tfes.org/The_Conspiracy
Back

12. "A geophysical planet definition", Matt Williams, Phys.org, 2/22/2017
https://phys.org/news/2017-02-geophysical-planet-definition.html
Back

13. Flat Earth Debunk Visualization, YouTube, posted Oct 8, 2015 by David Ridlen, https://www.youtube.com/watch?v=uexZbunD7Jg
Back

Videos Showing the flat Earth model
Flat earth Model
https://www.youtube.com/watch?v=DUQqd87pRIc

Night & Day in Flat earth
https://www.youtube.com/watch?v=hiOhsKAR6OY

How the sun and moon work over the Flat Earth model
https://www.youtube.com/watch?v=gg4ZeGJiyNA

Articles debunking the flat Earth theory
"A flat earth, and other nonsense
Debunking ideas that would not exist were it not for the Internet"
Robert Carter and Jonathan Sarfati
Published: 13 September 2016, last updated 5 June 2017
http://creation.com/refuting-flat-earth

"Definitive (Observable) Evidence Regarding The Flat Earth | David Rives"
David Rives, September 1, 2016
http://thecreationclub.com/definitive-observable-evidence-regarding-the-flat-earth-david-rives/
(A video presentation)

"Is the Earth Flat?"
Danny R. Faulkner, May 24, 2016
https://answersingenesis.org/astronomy/earth/is-the-earth-flat/

Videos debunking the flat Earth theory

10 Things That Would Happen If The Earth Was FLAT
https://www.youtube.com/watch?v=Pa5X2rj65Qo

Flat earth debunk Visualization
https://www.youtube.com/watch?v=uexZbunD7Jg
(Very nice graphics)

"Flat Earth" Debunked! 50+ Reasons The Earth Is NOT Flat! Globe Earth Proof
https://www.youtube.com/watch?v=KnqBzncqS2U

Images:

All images - used by permission from the license holders as noted below

Einstein ponders flat earth theory - Composite by Duane Caldwell © Duane Caldwell 2017
Gravity on Flat Planet Earth Conception © Artur Balytskyi | Dreamstime (used by permission, updated by Duane Caldwell)
Einstein - By Underwood and Underwood, New York [Public domain], via Wikimedia Commons
Blackboard and thought bubble - © dragonstock | Fotolia (used by permission)