## Glass of Water

Earth’s gravity causes water’s surface to curve with the same radius as Earth’s. On glass with a diameter of 10 cm, Earth’s gravity causes the water to form a curvature of 0.00000002 cm, outside other factors like surface tension.

Flat-Earthers like to demand that we prove water curvature in a glass of water. In reality, whatever the container, the curvature of the water surface remains the same as Earth’s radius. On a glass of water, it will be too small to observe.

## Wet, Spinning Tennis Ball False Analogy

The gravitational acceleration exerted by the mass of a wet, spinning tennis ball is too small compared to the centrifugal acceleration generated by its rotating motion. As a result, the water escapes away from the tennis ball, unlike Earth.

A wet spinning ball is a sphere, spinning & wet, like Earth. But the water goes away from the ball, unlike Earth. Flat Earthers use it to “disprove” spherical Earth. In reality, the magnitude of the involved accelerations in the two cases are different.

## Moving Vehicle Analogy: Inside vs Outside of the Vehicle

The moving vehicle analogy is often presented to explain how Earth’s rotation does not seem to affect an object’s motion. Similarly, a ball released inside a moving vehicle will not fall rearward because it retains its inertia.

Flat-Earthers offer the moving open-air vehicle as if it is the “correct ” analogy. In reality, with their analogy, the air moves relative to the vehicle, which exerts an additional force that does not exist in the fact being explained. Their analogy fails to represent the fact being explained.

## Refraction and Water

Refraction is the change in the direction of light due to the change in the medium’s refractive index traveled by the light. It is convenient to use water in a demonstration of refraction. But water alone is not the cause of refraction.

Flat-Earthers falsely claim that just because our atmosphere has water vapor in it, it will produce the same effect as any demonstration of refraction involving water. In reality, it requires far more reasoning than just that water is involved.

## Coin on a Table “Experiment”

Flat-Earthers performed the coin on a table “experiment” to “explain” how a sunset can occur on a flat Earth. Instead, it tells us more about their confirmation bias.

This is probably one of the most ridiculous flat-Earth arguments. It is so obviously wrong that many of us are having trouble explaining it and cannot accept that a member of the human race can fall for it.

## Camera Entrance Pupil Size and the Zoom Factor

The entrance pupil is the opening in front of a camera that allows light to enter. If it is partially obscured, light can still come through the unobscured part, and the camera can still see the object.

In one of those “experiments,” flat-Earthers placed an obstacle in front of a camera, very close to the lens, so that an object is partially visible. At the widest angle setting, the person appears partially visible. But it turned out that zooming in will fully reveal the person. Flat-Earthers claim it is how objects can vanish behind the horizon if Earth is flat and how they can reappear by zooming in. In reality, zooming enlarges the camera’s entrance pupil, letting the camera to see over the obstacle.

## Teaching Aid

Teaching aids are used by teachers to help students learn a subject more easily. A scale model of an eclipse is a teaching aid. It is not presented as evidence about how an eclipse can occur, but to help students to understand the mechanism of an eclipse.

Flat-Earthers often incorrectly consider a teaching aid is presented as if it is evidence of a phenomenon, then demand a similar thing as “evidence” of another phenomenon. In reality, a natural phenomenon is studied from the observation of the phenomenon itself. A teaching aid is there merely to help students learn.

## Moving Vehicle Analogy and the Physical Barrier Excuse

We cannot feel the Earth rotating, and to explain the phenomenon, we usually use the moving vehicle analogy. If the vehicle is moving at a constant speed, we will not be able to sense the motion. We cannot feel the motion of Earth because of the same reason.

Flat-Earthers invented the excuse that we are standing on Earth, not inside it, to falsely reject the explanation.

## False Analogy in the Use of Scale Models in Flat-Earth “Experiments”

Flat-Earthers like to use scale models to represent an actual object. They would apply the facts they observe from the model to the actual object itself. It is the fallacy of false analogy. The two situations can be substantially different. Just because both the scale model and the real object looks the same, it does not mean they are similar in another aspect.

Observation of the real object is stronger evidence than any argument from analogy —like using a scaled-down model of the real object. Using an analogy to dismiss the result of direct observation of the real object is unreasonable.

## The Ball and Water ‘Experiment’

Gravity is the attraction between objects with mass. The higher the mass, the greater is the gravitational attraction. Gravity is not the result of the shapes of the objects.

Flat-Earthers like to perform the ball-and-water ‘experiment.’ They spray water to a ball, then observe the water does not stick to the ball the same way the ocean water curves over the surface of the Earth. They would wrongly conclude that “gravity does not exist.” Gravity does not come from the spherical shape of objects, Continue reading “The Ball and Water ‘Experiment’”

## False Analogy

A false analogy is a fallacy in which similarity in one respect of two concepts, objects, or events is taken as sufficient to establish that they are similar in another respect in which they are actually are not similar.

Almost all of what flat-Earthers happily claim as “experiments” are actually false analogies. They would take everyday objects and use them as analogies for actual objects. In reality, a shared similarity in both the analogy and the real thing is not sufficient to ‘prove’ both are similar in some other respect.

## Football Field and ‘Flat-Earth Convergence Experiments’

A properly designed football field does not lie perfectly flat. Its middle portion is slightly raised to promote runoff of excess water. Without it, the field can become muddy & uncomfortable.

Some flat-Earthers conducted the perspective convergence ‘experiment’. They put a camera on the surface of a football field, and record a person walking away across the field. The person started to disappear from his feet first. Because they felt the football field is flat, they took the wrong conclusion that the person disappeared due to ‘perspective’. They were wrong. The field is, in fact, not perfectly flat. If it is perfectly flat, the person would appear fully at the end of the field.

## The so-called “Experiment” Done by Flat-Earthers

We often see flat-Earthers create a ‘miniaturized physical model’ of a real object and present them as ‘proof’ in support of flat-Earth and against spherical Earth. Their M.O. is to observe if the model remotely resembles the actual object in a particular way. If it does, then it is enough for them to conclude the model describe how the real object works.

Conversely, if a real object cannot be miniaturized and still have the same behavior as the original object, they would conclude that the behavior of the original object doesn’t exist.

They would wrongly call creating such models “doing an experiment”.

## Kettle Logic: Conflicting ‘Explanations’ in the Flat-Earth Model

Kettle logic is making multiple contradicting arguments in an attempt to support a single point or idea.

Kettle logic occurs very frequently in the flat-Earth community. If they meet a natural phenomenon cannot readily be explained using the flat-Earth model, they would often devise ‘experimental models’ to ‘explain’ how the said phenomenon can happen in a flat-Earth.

The problem? These models are in conflict with each other.

## Confirmation Bias

Humans have cognitive biases that can affect our judgments. One of these cognitive biases is the confirmation bias. Because of the confirmation bias, we tend to seek the information confirming our preexisting beliefs.

Confirmation bias is a fact of life, and all humans have it. Confirmation bias can result in different subjective opinion from a different subject. A characteristic of any pseudoscience —like the concept of flat-Earth— is that they don’t try to minimize the confirmation bias, but they actually encourage it.