Some people are confused that a full moon is visible all night, and think if the full moon is the result of the opposition of the moon from the sun, then a full moon should be visible only at midnight.
Flat-Earthers who have such spatial visualization problem take a step further and use it as ‘evidence’ that the Earth is not a sphere. They are wrong. The full moon phenomenon can easily be explained in the spherical Earth model.
Continue reading “Geometry of a Full Moon”
We cannot travel to another location by hovering inside a helicopter and wait for the Earth to rotate below us until we are above our destination. The reason is the phenomenon of inertia.
Flat-Earthers claim that we cannot do such a thing as ‘proof’ of a motionless Earth. They are wrong. When on the ground, the helicopter itself is already moving at the same velocity as Earth’s surface.
Continue reading “Helicopter and Earth’s Rotating Motion”
There are several models explaining the figure of the Earth. These models vary in the way they are used, in their complexity and in the accuracy with which they represent the size and shape of the Earth. These models are sphere, ellipsoid, and geoid.
Flat-Earthers often take the existence of these multiple models as evidence of disagreement among scientists, and that the shape of the Earth is still in contention. They are wrong. All these models are valid models, only with different complexity and accuracy.
Continue reading “The False Dilemma of the Figure of the Earth”
Most combustion engines work with oxygen from Earth’s atmosphere as its oxidizing agent in the combustion process. But in the case of rockets, there’s no oxygen in space. It would have to bring the oxidizer in addition to its fuel or use monopropellant which doesn’t require an oxidizer.
Flat-Earthers claim rockets should not be able to work in space because there’s no oxygen in space. They are wrong. The lack of oxygen in space is merely an engineering problem which is not impossible to solve. Rockets are engineered to carry its oxidizer or utilize monopropellant which does not require an oxidizer.
Continue reading “Rockets and the Lack of Oxygen in Space”
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”.
Continue reading “The so-called “Experiment” Done by Flat-Earthers”
Drag is a force acting opposite to the relative motion of an object moving with respect to a surrounding fluid. The higher the density of the fluid, the higher the magnitude of the drag.
Flat-Earthers claim that it is impossible for satellites to have such high speed. Usually, they would compare the speed of satellites to something like the SR-71 Blackbird, which holds the record as the fastest aircraft. They are wrong. At the altitude where satellites reside, the air density is several magnitudes smaller compared to near the surface, and thus, the drag experienced by satellites is also several magnitude smaller.
Continue reading “Drag”
“If the Earth is rotating, why when we throw a rock upward, it would fall to the original location?” The explanation is that the rock maintains the momentum before it is thrown. Before it is thrown, the rock has the same velocity as the surface of the Earth, it does not suddenly lose its momentum after being thrown, and there’s nothing exerting a force to alter its trajectory.
We usually use the moving vehicle analogy to illustrate this. If we throw the rock upward inside a moving vehicle, it would also fall to the original location, despite the fact that the vehicle is moving.
Flat-Earthers reject the analogy. Their usual excuse is that the atmosphere is not separated from space, and the rock is thrown “inside” the vehicle, separated by the body of the vehicle from the outside. They offer the analogy of being on the top of a moving vehicle as the correct analogy. They are wrong.
Continue reading “The Moving Vehicle Analogy”
An object falls down because of Earth’s gravitational attraction. But some denominations of flat-Earth insist that an object falls down due to its density, not gravity.
By putting two objects of an equal density and different mass against each other using a balance, we can easily determine that the density of the object is not the reason it falls down.
Continue reading “Density and the Balance Experiment”
Classical physics —like Newton’s law of motion, and Newton’s law of universal gravitation— has been superseded by Special Relativity, General Relativity, and Quantum Mechanics. But it doesn’t mean classical physics is wrong. Classical physics is still applicable when the parameters approach common, terrestrial values we use every day.
Pseudoscientists —including flat-Earthers— often misunderstood this and take the fact that classical physics is still being taught in schools as ‘proof’ of deception and the failure of modern science to explain the world. They are wrong.
Continue reading “Classical vs Modern Physics”
The Nile never flows uphill, or in other words, ascend to a location farther from sea level anywhere in the Nile basin.
Flat-Earthers often claim that if the Earth is spherical, then the Nile will have to flow uphill to overcome the curvature of the Earth. They are wrong.
Continue reading “The Earth is Spherical and The Nile Never Flows Uphill Anywhere”
The directions of up and down are determined from the direction of the Earth’s gravitational acceleration. Up is in the opposite direction, and down is in the same direction as the Earth’s gravitational acceleration.
Flat-Earthers are often seen making fun of this fact. They show us ‘upside down’ pictures taken in the southern hemisphere. They are wrong. To anyone in the southern hemisphere, down is in the same direction as the Earth ‘s gravitational acceleration, the same as anyone in the northern hemisphere.
Continue reading “The Directions of Up and Down”
If Earth’s gravity pulls everything towards the Earth, then how can satellites stay up there and are not falling towards the Earth?
The answer is that satellites orbit the Earth. They have the correct velocity with respect to Earth’s position and gravitational pull.
Continue reading “How Satellites Can Orbit and Stay Up There”
The Mississippi River never flows uphill, or in other words, ascend to a location farther from sea level anywhere in the Mississippi River basin.
Flat-Earthers often claim that if the Earth is spherical, then the Mississippi River will have to flow uphill to overcome the curvature of the Earth. They are wrong.
Continue reading “The Earth is Spherical and The Mississippi River Never Flows Uphill Anywhere”
A widespread misunderstanding within the flat-Earth victims is related to velocity/speed. They seem to think velocity is absolute, while in reality it is measured from a specific frame of reference. Example:
“If the Earth is in motion around the Sun at 30 km/s, and Apollo traveled at only 11 km/s, then how could Apollo astronauts possibly make it back to the Earth?”
We used to measure velocity/speed relative to the surface of the Earth. But it is not always like that.
Continue reading “Velocity is Measured From Specific Frame of Reference”
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.
Continue reading “Free Fall”
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.
Continue reading “The Earth is Spherical and The Amazon Never Flows Uphill Anywhere”
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.
Continue reading “Equipotential: a Property of the Surface of Water”
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.
Continue reading “Hot Air Balloon and the Force of Gravity”
If we walk by pushing our feet against the ground, birds fly by flapping their wings against the air, and fish swim by pushing their fins against water; then how can possibly a rocket move in a vacuum?
Rockets are able to move in space by making use of the law of nature described in the Newton’s laws of motion, and the law of conservation of momentum.
Continue reading “How Rocket Engines Work in A Vacuum”
A lot of misconceptions within the flat-Earth circles are present only because of the lack of understanding on how forces work on an object.
Continue reading “Force Vectors”