Refraction of Laser Beam

Lasers are distinguished from other light sources by their coherence, or that their frequency and waveform are identical, and the output being a narrow beam. But lasers are still a form of light and exhibit the same characteristics as other light sources.

Flat-Earthers assume lasers always travel in a straight line, not affected by the medium. They use this incorrect assumption in their “experiments” to “prove” a flat Earth. In reality, like other light sources, atmospheric refraction can bend laser beams.

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Southern Hemisphere: Where Many Flat-Earth Claims are Disproven

Flat-Earth is a con initially designed to appeal to the potential victims in the Northern hemisphere. At a glance, some of the claims are seemingly in line with observation in the Northern hemisphere, but they are easily disproven when tested in the Southern hemisphere.

90% of all humans live in the Northern hemisphere. And it made sense of these con artists to invent the “facts” with the northern markets in mind while hoping nobody would bother going to the Southern hemisphere only to verify them. It was realistic in the 19th century, but today, everyone can verify the southern facts. There is no excuse for us to become flat-Earth victims, especially those already living in the Southern hemisphere.

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Flat-Earthers’ Excuse to Dismiss Observation of the Sky

Flat-Earthers like to dismiss evidence of spherical Earth if it is in the form of an observation of the sky. In reality, many of the observed motions of celestial objects can only be explained if Earth is a sphere. These observations are sufficient to prove that Earth is a sphere and rule out a flat Earth.

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Horizontal Motion of Smoke

The horizontal motion of a rising smoke occurs due to the horizontal motion of air relative to the object releasing the object. If the air is stationary relative to the object releasing the smoke, then the smoke will rise straight upward.

Flat-Earthers claim the motion of smoke rising straight up “proves” Earth is stationary. In reality, the horizontal motion of smoke is caused by the motion of surrounding air, relative to the object releasing the smoke, not the motion of the object itself.

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Isaac Newton and the “Hypotheses non Fingo”

Isaac Newton formulated the law of universal gravitation, which adequately explained the motion of all bodies in space known at his time. He also showed it is the same law that is causing everyday objects to fall on Earth.

In his famous phrase “hypothesis non fingo,” Newton stated that he did not know what causes gravity and refused to speculate. Flat-Earthers use it to discredit him. In reality, just because he did not know what causes gravity, it does not mean his law of universal gravitation is wrong.

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Transporting the Apollo Lunar Roving Vehicle

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The Apollo Lunar Roving Vehicle (LRV) is a battery-powered rover used on the Moon in the last three Apollo missions. Each LRV was carried to the moon folded up in the Lunar Module’s quadrant 1 bay, which was kept open to space.

Flat-Earthers claim the LRV is too large to fit inside the Lunar Module and they use it to dismiss the mission as fake. In reality, the LRV was carried folded up in open cargo space, similar to transporting a bicycle using a bike carrier attached to a car.

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Geocentric Coordinate System Does not Imply Geocentrism

In astronomy, we use a celestial coordinate system to specify the position of celestial objects, like satellites, planets, stars, etc. Each of the coordinate systems has an origin, which can be the observer (topocentric), Earth (geocentric), the Sun (heliocentric), the Moon (selenocentric), or any other location. We choose a specific coordinate origin according to convenience and suitability for the problem at hand.

Some coordinate systems are described as “geocentric,” and flat-Earthers use it as “proof” of geocentrism, or that Earth is stationary and the center of the universe. In reality, it is just the origin of the coordinate. “Geocentric” here means Earth is the origin of the coordinate system. As we live on Earth, a geocentric coordinate is useful for many purposes.

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True Horizon and Linear Perspective

In graphical, linear perspective, the horizon is the horizontal line where the vanishing points for level objects lie. However, as the Earth is a sphere, the horizon of linear perspective is not the same as the true horizon, which is the line that we observe separating Earth from the sky.

Flat-Earthers claim that the observed horizon is produced by the law of perspective. In reality, from a high vantage point, we can try extending level and parallel lines to find their vanishing points. In many cases, they will end up above the true horizon.

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Salar de Uyuni and Other Salt Flats

Salt flats are flat expanses of ground covered with salt and other minerals. Salar de Uyuni in Bolivia is the world’s largest salt flat. Salt flats appear visibly flat, but they still follow the curvature of Earth.

Flat-Earthers claim the apparent flatness of Salar de Uyuni and other salt flats “proves” a flat Earth. In reality, while salt flats appear flat, they still follow Earth’s curvature. On a salt flat, the bottom part of a distant object will be obscured by Earth’s curvature, similar to at sea.

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Airplanes Going Over Earth’s Curvature

To an observer on the ground, an airplane at 36000 ft will start going over Earth’s curvature at a distance of 400 km. However, we are also limited by atmospheric visibility. In an extremely best-case scenario, we can only see up to 240 km.

We can easily see ships going over Earth’s curvature, and flat-Earthers like to demand us the same thing for airplanes. In reality, at the typical distance a plane does that, it is far out of visibility range. But if it is very low, like when approaching a runway to land, it is possible to see the plane going over the curvature of the Earth.

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Archimedes and the Surface of any Fluid

In the 3rd century BCE, Archimedes of Syracuse wrote what we now call the Archimedes’ principle in his book “On Floating Bodies” using the spherical Earth model.

Flat-Earthers like to misuse Archimedes’ principle as if it supports their claim that Earth is flat. In particular, they abuse Archimedes’ principle as if it is a competing explanation against gravity. In reality, Archimedes and other Greek scientists at the time already knew Earth is a sphere, and he explicitly mentioned it in his writings.

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Alignment of Planets

Planets are in motion around the Sun. Sometimes the planets’ positions are aligned that they appear close to each other in the sky, and less frequently, involving more than two planets.

One such alignment of planets occurred in May 2011 where Mercury, Venus, Mars, and Jupiter are all appeared close together. Mercury and Venus are closer to the Sun than Earth, while Mars and Jupiter are farther. Flat-Earthers cannot understand how all of these planets can appear close to each other in the sky, and they use it to discredit science. In reality, this diagram can easily explain the general positions of the planets during the phenomenon.

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Cellular Network vs Satellite Communications

A cellular network consists of several cells. Each of the cells is serviced by a base station operating with a specific frequency. Adjacent cells are each assigned a different frequency. A non-adjacent cell will be able to use the same frequency without interfering.

Flat-Earthers like to tell us that a single satellite can cover an entire country, yet phone operators choose to install base stations everywhere instead. Then they use the fact to “prove” that satellites do not exist. In reality, a cellular network has several advantages compared to one single base station, like a satellite.

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Observing Earth’s Curvature From a Flight

At the cruising altitude of a jet airliner, Earth’s curvature is too slight for us to notice casually. But with planning and careful observation, it is not impossible to see the curvature. Continue reading “Observing Earth’s Curvature From a Flight”

Image of William Shatner Wearing the Same Jacket as Jeff Bezos

In 2021, William Shatner becomes the oldest person to travel to space after he went up with Blue Origin. Conspiracy theorists noticed a Photoshopped image of Shatner wearing a Blue Origin Jacket. And they use the image to discredit spaceflight.

Conspiracy theorists —including flat-Earthers— were quick to notice the Photoshop job, yet unable to notice the glaring fact that Blue Origin had nothing to do with it.

Even if they did it, it does not “prove” anything. This incident, however, serves to demonstrate the inability of conspiracy theorists to use their critical thinking skills.

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Modus Operandi of Flat-Earthers to Obtain “Images of Flat Earth” to Deceive Us

If Earth is a sphere, how is it possible for flat-Earthers to show us “images of flat Earth” taken from high-altitude balloons? These are the modus operandi of unscrupulous flat-Earthers to obtain such images in an attempt to deceive us.

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Camera Exposure Settings in the Apollo Missions

Cameras used by Apollo astronauts were equipped with ASA 160 film (equivalent ISO 160 in digital cameras). And they were instructed to use the following camera exposure values: shutter speed 1/250s, aperture f/5.6 (in shadow), and f/11 (sunlit). We can try the same values to everyday scenes and see how they end up in the results.

Stars are not visible in the photos from the Apollo missions, and flat-Earthers use the fact to dismiss them as fake. In reality, by using the same exposure settings as the astronauts used, we cannot get the stars to appear either. Therefore, there is no reason to expect stars to appear in photographs taken by Apollo astronauts.

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Curvature of Water Surface

If Earth is a sphere, why is the surface of water always flat?

Due to Earth’s gravity, water seeks the lowest potential or as close as possible to the center of Earth. It forms a practically spherical surface centered on Earth’s center. The width of the surface in everyday cases is tiny compared to Earth’s radius. Thus, the water surface looks practically flat but not perfectly flat.

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Misconception about the Second Law of Thermodynamics

In an online lecture, an MIT professor explained the second law of thermodynamics. One of his examples is a container filled with gas next to another filled with a vacuum. If the wall is removed, the gas will rush to fill the newly available volume. However, it is only a simple model that does not attempt to explain everything about the system.

Flat-Earthers abuse the lecture to “prove” it is “impossible” for the atmosphere to exist next to a vacuum. It becomes a flat Earth talking point as if the lecture shows us that spherical Earth “violates” the second law of thermodynamics. In reality, the gas inside the container is also affected by gravity and will also have a pressure gradient, just like the gas outside. But it is not within the scope of the lecture.

And if we ask the lecturer if Earth is flat, he will surely say no.

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Where’s the Curvature?

A human eye can only visually perceive the curvature of the Earth if we are at a considerable altitude from the surface, which is still beyond the reach of most humans today. A commercial jet airliner is the highest position realistically attainable by most humans today. We can only perceive very slight curvature at such altitude and, even then, only in an ideal condition.

The basis of flat-Earthers’ belief is that the horizon appears flat. They would say if we cannot see the curvature, then there’s no curvature, and therefore, the Earth is flat. In reality, only a few people can travel high enough to see the curve.  The highest we can realistically go is by getting on a commercial jet airliner, which can only go about 11-15 km up, only a fraction of Earth’s radius.

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