Many flight routes cannot possibly exist if Earth is flat. Flat-Earthers showed the availability of the same routes with a stop to “prove” the non-stop routes do not actually exist. In reality, there are reasons airlines provide these routes with a stop, and some passengers do prefer to fly these routes.
Chinese astronauts performed science demonstrations at the Tiangong Space Station. One of these demonstrations involves a glass of water and a ping-pong ball. Flat-Earthers saw a photo of the glass of water from the set, and they used it to discredit spaceflight. They claim that if it is really in space, then the water and glass should float.
In reality, the glass was attached to the table, and the water stayed in the glass because of adhesion between the glass and water, not gravity. The surface of the water also bulges and is not level with the glass or the table, as expected in a microgravity environment.
The astronauts used the set to demonstrate buoyancy in space. They pushed a ping-pong ball into the water, and it did not float like on Earth. At the end of the demonstration, they detached the glass from the table and floated it with the water & the ping-pong ball still inside it, and everything behaved as it should in a microgravity environment.
A flame can produce a shadow if the other light source is much brighter, then refracted by the temperature difference, or the flame produces soot, steam, or other combustion products.
Flat-Earthers discovered images of flames not casting a shadow, & when they saw in a photo that a rocket’s exhaust casted a shadow, they used it as “evidence” it was faked. In reality, a flame can produce a shadow under the right conditions. Rockets have opaque combustion products, & in daylight, are lit by the very bright sun.
Predictive programming is a made-up element of conspiracy theories that supposes conspirators hide references in popular media before an atrocity takes place. When it occurs, the public has supposedly softened up and accepts it rather than resisting.
Conspiracy theorists invented the so-called predictive programming to allow them to use similarities in books, music, movies, etc., as “evidence” that the atrocity was intentional & caused by a conspiracy. It also gives them a convenient excuse to justify why these conspiracists would even purposely leak their secret plans of an atrocity in popular media.
A sundial tells the time of day from the position of the shadow of its gnomon as cast by the sun. The gnomon is usually raised parallel to Earth’s axis of rotation, so its shadow will always fall to the same line despite the sun’s annual apparent motion.
Aligning the gnomon to the Earth’s axis of rotation allows the sundial to be accurate throughout the year. All of this happens because Earth is a rotating sphere orbiting the sun with a tilted axis.
Flat-Earthers incorrectly claim that sundial works because Earth is flat. In reality, sundials are designed with the knowledge Earth is a sphere. Real-world sundials cannot possibly work if Earth were flat. If Earth were flat, we would have constructed sundials in a very different design.
“Force the line” is a method proposed by flat-Earthers to determine Earth’s shape. It is an unrealistic method involving building a very long structure that is maintained flat for its entire length.
“Force the line” is just an exercise of one single proof fallacy. They ignore the overwhelming amount of evidence in support of spherical Earth, withholding their judgment for that one specific method, which is very difficult to execute and prone to errors.
Foucault’s pendulum proves Earth’s rotation. In the Northern Hemisphere, the pendulum rotates clockwise. In the Southern Hemisphere, it rotates counterclockwise. The pendulum turns faster if it is closer to the pole. On the Equator, the pendulum does not rotate.
Flat-Earthers invented various excuses to discredit Foucault’s pendulum. In reality, anyone not near the Equator can easily repeat the experiment, and it will give the expected result.
Ignorance is the lack of knowledge or information. Motivated ignorance is the state of ignorance and the desire to remain in such a state. Humans from 5000 years ago might not know that Earth is a sphere, but they are different from modern flat-Earthers. Flat-Earthers are not just ignorant; they are motivated to remain ignorant.
Pilots can easily observe that Earth is a sphere, either by visual observation or from the aircraft’s flight instrument.
The level indicator is above the visible horizon. It is the dip of the horizon caused by the fact that Earth is a sphere. Earth’s horizon itself is visibly curving. The horizontal component of the velocity vector is often not the same as the plane’s direction due to the wind & the Coriolis effect from Earth’s rotation.
Earth pulls all objects downward by the same gravitational acceleration of 9.8 m/s². But the force of gravity exerted by Earth on an object still depends on its mass. An object with a greater mass has a greater force of gravity (also called weight).
Flat-Earthers claim that if greater mass means a greater force of gravity, a bowling ball in a vacuum should fall faster than a feather. In reality, they confuse acceleration with force. Both fall at the same speed because the gravitational acceleration is the same on both, but their forces of gravity are different.
The sun emits sunrays in every direction. But as the sun is very far, the sun rays that reach us are practically parallel. From Earth, any two sun rays form a maximum angle of ~0.53°. Sun rays are practically parallel, but not perfectly parallel.
For most practical purposes, we can assume sun rays are parallel for simplification. But in other cases, the small angle is critical to the problem & we need to take it into account.
The fallacy of appeal to anonymous authority occurs if an unspecified source is used as evidence of the claim, and it is impossible to verify the source & the argument’s credibility.
Many flat-Earthers claim to know someone who knows someone who knows a pilot, surveyor, scientist, professor, etc., who has proven Earth is flat. But it is impossible to verify these supposed “experts” & their views directly. Inventing an “expert” to support their position is the fallacy of anonymous authority.
The Lake Pontchartrain causeway and transmission lines demonstrate Earth’s curvature. Flat-Earthers attempt to dismiss it using aerial photos where it is more difficult to see the curved landmarks over water.
On the other hand, from these alternative vantage points, it becomes easier to reveal the horizontal curvature by magnifying vertically. Because of the possibility of lens distortions, some of the images are inadequate evidence of the curve. However, all of them are insufficient evidence of a flat Earth.
During a total solar eclipse, the Moon’s side facing Earth does not receive sunlight but still receives light reflected from Earth’s surface. The phenomenon is called Earthshine and can be captured using a camera with a long exposure.
Flat-Earthers demand visual evidence of the Moon blocking the Sun during a solar eclipse. Earthshine provides this visual evidence & shows that the Moon is blocking the Sun.
Objects fall down because of gravity. Flat-Earthers deny gravity & wrongly claim they fall down because of density. For a demonstration, we can ask any flat-Earthers the following simple physics problem:
“A rigid object is released at the height h above the ground, what is the object’s velocity right before it hits the ground?”
Flat-Earthers will not be able to solve this free-fall problem without using the gravitational acceleration g=9.8 m/s². Some will call it by a different name, showing that it is just a “branding” problem. Practically all the time, they will not involve density to solve it, if they can solve it at all.
The “Field Artillery Manual Cannon Gunnery” (TC 3-09.81) is a manual from the US Army explaining the operation of field artillery. From the manual, we know the operators of field artillery are required to account for Earth’s rotation.
Flat-Earthers wrongly claim that an artillery operator never needs to account for Earth’s rotation. In reality, from this operational manual, we know their claim is incorrect.
The Tiangong space station is equipped with a panoramic camera. It produces panoramic video in the equirectangular projection. It has a field of view of more than 180° & can see “behind” the camera. The image is unlike what our eyes see.
Flat-Earthers noticed the “funny” shape of the Earth from the Tiangong’s live stream & use it to discredit the mission. In reality, the image is panoramic. It shows the view behind the camera & cannot be compared to what our eyes would see.
Ocean tides occur because the water flows from locations with a low tide to those with a high tide on the other side of the world. On the other hand, the world’s lakes are not interconnected, & therefore, no significant tides can occur.
Tides are much smaller in lakes, and flat-Earthers use them to discredit gravity. In reality, lakes are not connected. Water in a lake cannot flow to another on the other side of Earth and cannot cause a low tide to one & high tide to another.
In 1899, Ebenezer Breach, a flat-Earther, threatened to sue Sir John Gorst, UK’s secretary of education, for teaching globe Earth. The story is the source of a hoax in today’s flat Earth communities.
In our education, we are told that the Earth is a sphere because it is a sphere. It would be wrong if our educational system were to teach us that the Earth is flat.
Flat-Earthers claim that our educational system is a form of propaganda & indoctrination. In reality, we were told Earth is a sphere because it is a sphere. It would be misleading if they told us other than that. Propaganda & indoctrination is what is actually happening in flat-Earth communities themselves.