### Perspective Compression: Determining If a Curvature Exists

Soundly’s pictures and videos of Lake Pontchartrain power lines and causeway stirred up the flat-Earthers’ nests. They clearly show the curvature of the Earth, where it is usually hard to discern. For the rest of us, those pictures are just the consequence of the fact that the Earth is a globe.

Flat-Earthers can’t take this, and they invented various excuses to attack the credibility of these pictures and videos. Some of them look for specific vantage point where it is impossible or very hard to discern the curvature.  They would conclude if the curve is not seen from these vantage points, then it should not be visible from Soundly’s viewpoints.

### Curvature of the Horizon in High-Altitude Balloon Footage

High-altitude balloon footage is often abused by flat-Earthers to show us that the Earth is flat when seen from a high altitude.

We analyzed more than two dozens of footage taken from high-altitude balloons on YouTube, and we can easily conclude the curvature is there and usually easy to spot, including in the cases where flat-Earthers use the video as ‘proof’ of a flat Earth.

### Quote-Mined Einstein Statement

Flat-Earthers quoted Einstein’s statement out of context to give the appearance that he gave credence to the notion that Earth is stationary. In reality, Einstein never said the Earth is stationary.

The quote came from his Kyoto address “How I created the theory of relativity,” December 14, 1922.

### Free Fall

Things fall down because of gravity. The mass of the Earth causes everything to fall down at 9.8 m/s² near the surface of the Earth. This constant is called ‘gravitational acceleration’ and usually denoted by ‘g’.

Most flat-Earthers deny the existence of gravity. According to them, things fall down because of density or buoyancy, not gravity. They are wrong.

### How the Sun ‘Burns’ Without Air in Space

A candle gets its flame from combustion, a chemical reaction. The hydrocarbon that formed the candle reacts with oxygen, and we get carbon dioxide, water, and heat energy as the results. The oxygen is obtained from the air. If the air supply is cut off —for example by covering the candle with a glass— then the reaction will stop, and the flame goes out.

We hear flat-Earthers often claimed that it is impossible for the Sun to be in space. They said the Sun burns, and therefore it requires oxygen. Space is empty, so it is impossible for the Sun to be there. They are wrong. The reaction that is occurring in the Sun is not combustion. It works differently from what happens with the candle.

Nuclear fusion powers the Sun.  It fuses hydrogen atoms into helium atoms. All the necessary component for the reaction to happen is in the Sun, and the reaction doesn’t require matters from external sources.

### The Eratosthenes Experiment: Proving the Earth is Spherical

In 205 BC, Eratosthenes successfully determined the circumference of the Earth by measuring the length of the shadow cast by a rod. He did the measurement in Alexandria and timed it to coincidence when the Sun is directly overhead Syene.

2222 years after that, some flat-Earthers tried to refute the Eratosthenes experiment. They say the experiment can be applied to the flat-Earth model.

### The Curvature of the Water Surface

Flat-Earthers mention the curvature of water a lot. According to them, the curve of the water can never be observed, and thus, the Earth is flat.

The problem with such an argument is that they usually conclude that from a very small amount of water. Water in a glass or a bucket will practically look flat. Not because there is no curvature due to Earth’s gravity, but because the water is in such small amount so that the curvature is minuscule and impossible to observe, let alone with the naked eye.

### The Earth is Spherical and The Amazon Never Flows Uphill Anywhere

The Amazon never flows uphill, or in other words, ascend to a location farther from sea level anywhere in the Amazon basin.

Flat-Earthers often claim that if the Earth is spherical, then the Amazon will have to flow uphill to overcome the curvature of the Earth. They are wrong.

### The MH370 Disaster and the Inability of the GPS System to Locate It

The GPS system is one-way. The satellites broadcast signals. GPS devices receive and process the signals to determine their location.

Flat-Earthers often point out the fact we were unable to locate the ill-fated MH370 as ‘evidence’ GPS doesn’t work and therefore doesn’t exist. They are wrong. GPS satellites never receive any signal from GPS devices, and it is not possible for them to locate MH370.

### Equipotential: a Property of the Surface of Water

Gravity causes water to seek the lowest potential, which can be simplified as the position as close as possible to the Earth’s center of gravity. As a result, the surface of the water will have equipotential surface and form an approximately spherical surface which has the same center as the Earth. Every location along the surface has the same potential.

### The Sydney-Santiago Flight Route: An Impossible Route on the Flat-Earth Model

We can use the duration of a flight route to roughly determine the distance between two locations. Then, we can use this to determine which model better represents reality: the flat-Earth model or the spherical Earth model.

In the flat-Earth Model, the distances between two locations become more unreasonable as we go further south. To illustrate this fact, we can use the flight route of Sydney-Santiago to help us with the calculations. This flight route is one of the most southernly flight routes. Continue reading “The Sydney-Santiago Flight Route: An Impossible Route on the Flat-Earth Model”

### Atmospheric Refraction

Light waves are not always moving in a straight line. When it passes through a medium of a different refractive index, the waves will deviate. The phenomenon is called refraction and described according to Snell’s Law.

Earth’s atmosphere has variation in air density that depends on the altitude. As the refractive index changes with the density of the medium, light waves passing through Earth’s atmosphere also experience refraction.

### The Illusion of Clouds Appearing ‘Behind’ the Sun or the Moon

Sometimes, we can see clouds appearing as if they are behind the Sun or the Moon. Obviously, this is merely an illusion. But some flat-Earthers regard this as ‘evidence’ that the Sun and the Moon are close and apparently closer than some clouds. They are wrong.

### Why Tides Do not Occur on Lakes or Other Bodies of Water

All the seas and oceans around the world are connected. Water can freely flow between them. That’s the reason tide can occur on them.

On the other hand, lakes are isolated from one to another. Water cannot freely flow between them. That is the reason tide in meaningful amount cannot occur on lakes or any other bodies of water.

### Earthshine Proves the Moon Obscures the Sun During a Total Solar Eclipse

During a total solar eclipse, the Moon is right between the Earth and the Sun. Thus, the near side of the Moon does not receive any sunlight. But while it is dark, it still gets some light reflected by the surface of the Earth. This phenomenon is called Earthshine.

Some flat-Earthers argue that a solar eclipse is not caused by the blocking of the Sun by the Moon, but by another, mysterious celestial body. The reason is that eclipses are incompatible with their beliefs about the motion of the Sun and the Moon.

Earthshine proves that they are wrong.

### The Starburst Effect is not Evidence of CGI

In photography, the starburst effect gives the illusion of light rays from strong light sources in an image. The effect happens when the lens’ aperture is not a perfect circle, and it gets more pronounced under a narrower aperture.

Flat-Earthers often find themselves looking for any peculiarity —no matter how small or unbelievable— to discredit any picture they deem unacceptable to their misguided causes. One of this peculiarity is the starburst effect.

### The Aether Experiments are Never Evidence of Flat and Stationary Earth

Aether was the hypothetical material that fills the region of space. It was assumed to be the medium that allows light and gravity to propagate in space. Throughout the late 1800s and early 1900s, some experiments were carried out to prove if the aether exists.

Flat-Earthers (and geocentrists alike) often use the results of these experiments to support their case that the Earth is stationary. But they are wrong. These experiments were conducted to prove if the Aether theory, or if one of its competing hypotheses —like the Special Relativity— better explains reality.

### Bedford Level Experiment Confirmed the Curvature of the Earth

In 1870, Alfred Russell Wallace successfully demonstrated the curvature of the Earth to answer the challenge put forward by a flat-Earther, John Hampden.

### Long-Range Wi-Fi and the Curvature of the Earth

Wi-Fi is one of the most common ways of getting connected to the Internet. Practically all short-range wireless network use WiFi. Using specialized equipment, Wi-Fi is usable over a very long distance, even over hundreds of miles.

When designing a long-range Wi-Fi link, we must account for the curvature of the Earth.

### Hot Air Balloon and the Force of Gravity

A hot air balloon rises because it has buoyancy. Buoyancy is the upward force that is exerted on the trapped hot air because its density is lower than the surrounding air. If buoyancy is greater than the force of gravity — or the weight of the balloon—, then the balloon will rise.

The basic physics escape most flat-Earthers. To them, the fact that a hot-air balloon rises is an ‘evidence’ that gravity does not exist. They believe things go up or down because of density. They are wrong.