The Cavendish experiment was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate values for the gravitational constant.

Flat-Earthers are in a constant effort to discredit the Cavendish experiment. They would invent various “explanations” to “explain” the result of the experiments. However, the experiment was not only done once by Henry Cavendish in 1797-1798, and has been replicated numerous times by multiple independent parties for centuries, all yielding consistent results.


The Cavendish experiment consists of a wooden rod horizontally suspended from a wire, with two small lead balls attached to each end. Two more massive lead balls were placed near the smaller balls. Gravity would pull the freely suspended rod and small spheres toward the more massive balls.

Flat-Earthers are always trying to discredit the experiment by aiming their attention to the original experiment, and even toward Henry Cavendish himself as an individual. In reality, the experiment has been replicated numerous times and gave practically the same results. The term ‘Cavendish experiment’ refers not only to the original Cavendish experiment but also to the method and procedures from the original experiment. Anyone is free to attempt the Cavendish experiment, and when done correctly, they will get practically the same results.

https://youtu.be/jkjqrlYOW_0

https://youtu.be/Mcg2h--JDv4

The “8 inches” rule is also an approximation. It remains usable until up to about 100 miles. After that, it deviates from the correct value very quickly.

The correct formula being;

h = r - r cos(s/2r)

h = height
r = radius
s = arc length

Red Bull Stratos was a high-altitude diving project involving Felix Baumgartner. In 2012, Felix Baumgartner flew 39 km (24 mi) into the stratosphere in a helium balloon before free falling in a pressure suit and then parachuting to Earth. Flat-Earthers invented various excuses to dismiss the resulting footage from the project.


Fisheye lenses were used to record the footage of the jump. Flat-Earthers used the fact to rule out the apparent curvature in the videos as if the curve were produced by the fisheye distortions. In reality, the camera and the lens used were identified, and from that, it was possible to perfectly defish the footage. The defished footage still shows the curvature very clearly.

Before Felix performed the jump, he did test runs twice, using a different module. Flat Earthers identified several differences from the different footage of the drop and concluded it was a sloppy manipulation. In reality, there were two modules, one for the test jumps, and the other for the actual record-breaking jump.

From the published videos, the entire Earth’s surface visible to Felix was all land, and no ocean was in sight. Flat-Earthers questioned it: if Felix jumped from space, then Earth’s ocean around the US should be visible. In reality, Felix jumped from merely 39 km, not nearly high enough to call it “space.” From such an altitude above Roswell, NM, the ocean should not be visible, consistent with the published videos.

Flat-Earthers questioned that if the Earth is rotating, then why Felix jumped straight down to the same location? First, Felix still retained the inertia he had when he was still standing on the surface. And second, he did not jump straight down to the same location. He went up 39 km and landed 37 km away due to various factors, including the Coriolis effect from Earth’s rotation.

Accounting for the curvature of the Earth is not usually needed for narrow high-rise building projects. Designers only need to ensure the foundation is flat, and the curvature of the Earth becomes non-factor.

For projects that extend over a long distance, like roads, railroads, canals, etc., they are built along the curvature of the Earth, and specifically accounting for the curvature is usually not needed.

But when the project extends on a long distance, as well as extending upwards, then we have no choice but to take the curvature of the Earth into account. One of such projects is the Verrazano-Narrows Bridge, New York, United States.

The towers of the bridge are 1⅝ inches (41.275 mm) farther between the tops than at the base. The curvature of the Earth needs to be taken into account because the project extends on a relatively long distance as well as upwards. The height of the towers is 693 ft (211 m), and they are 4,260 ft (1,298 m) apart.

If the curvature of the Earth is not taken into account, then the two poles would not be straight towards to the center of Earth’s gravity, and the bridge will not be able to support itself properly. The cables would have to support some of the weight of the towers, as well as the load from the passing vehicles.

 1871, George Airy attempted to measure the drag of light that would change the stellar aberration of light by using a water-filled telescope, instead of an air-filled one. His observation did not indicate the change exists and does not support the Aether drag hypothesis, hence the popular name “Airy’s failure.” It does not support a flat & stationary Earth as the underlying phenomenon —the annual stellar aberration— can only occur if the Earth is in motion around the Sun.

The Michelson-Morley experiment in 1887 proved that if the Earth is in motion, then Aether could not exist. This experiment alone cannot confirm if the Earth is or is not in motion, but that does not stop flat-Earthers. The fact that the Earth is in motion had to be concluded from other observations.

Georges Sagnac in 1913 conducted an experiment where he rotated his interferometer. He concluded the Aether exists, but only because he was unaware of what we call now the Sagnac effect. This effect is used today in optical gyroscopes, and cannot possibly be utilized had the Aether theory is correct.

The Michelson–Gale–Pearson experiment (1926) was a very large interferometer designed to detect Earth’s rotation by measuring the resulting Sagnac effect. The experiment was successful and confirmed the angular velocity due to Earth’s rotation.

Flat-Earthers claim there is no scale model of the Solar System and use the fact to “prove” the failure of science to explain the world. The Sweden Solar System proves them wrong and gives us an idea about the problem of making a scale model of the Solar System.

In the Sweden Solar System, the Sun is depicted by the Globe Arena building (the Globen) in Stockholm, which is sphere-shaped with a 71 m diameter. Earth is represented by a sphere with a diameter of 65 cm, 7.6 km from the Globen. And the Moon is represented by an 18 cm sphere, about 20 m from the Earth.

The misconception is more than a century old. In 1881, Samuel Rowbotham wrote it in his book ‘Earth not a Globe, second edition.’ In 1885, another perpetrator of flat Earth, William Carpenter, also covered it in his book ‘One Hundred Proofs That the Earth is not a Globe.’ In 1890, Alex Gleason —who is more known for his so-called ‘flat Earth map’— also got his hands dirty spreading the misconception in his book ‘Is the Earth a Globe?’. And more than 100 years later, Eric Dubay repeated the same mistake in his book ‘The Flat Earth Conspiracy.’

All made the same mistake by misinterpreting the Suez Canal’s datum line which was 26 ft below sea level at the time of its initial construction. They claim if the Earth is a sphere, then the Suez Canal must be dug according to a straight line between 26 ft below sea level from either side, which would require digging 1666 ft deep below sea level in the middle of the Suez Canal.

They are wrong. The surface of the water is equipotential or is at the same level, including when the water flows through the Suez Canal. The engineers only need to ensure the canal bed is 26 ft deep, relative to the equipotential surface of sea water. Because the surface of the water curves, then the foundation of the canal will also curve along the curvature of the Earth.

Flat-Earthers often claim that “the horizon always rises to eye-level”, and thus ‘proving’ the flat Earth claim. Despite their insistence to use a water level to ‘prove’ water is flat, the same device can be used to demonstrate the dip of the horizon, proving the water surface has curvature, and consistent with the spherical Earth model.


A water level exploits the fact that water always finds its level. Looking at the surface of water formed in two vessels, we can aim at the horizon and determine the projected eye-level. If we are at a sufficient altitude, we should be able to observe that the horizon —the line separating the sky and the ground— lies below the eye-level.

As we climb higher, the larger is the dip. Conversely, as we approach sea level, the dip approaches zero.

Flat-Earthers often use water level as ‘proof’ that the surface of the water is flat. They are wrong. The surface of the water is level, or equipotential, but not perfectly flat.

Cellular phones do not function in a remote location, and flat-Earthers use the fact as “proof” that satellites do not exist. In reality, nobody claimed that cellular phones communicate with satellites. The phones that communicate with satellites are called satellite phones, and they still function in a remote location.


The major satellite phone providers in operation today are Inmarsat, Thuraya, and Iridium.

Various pictures showing satellites and space debris around the Earth are visualizations. They are not real photos taken from cameras. These visualizations were created by drawing the objects with sizes far larger than their actual dimensions. If they were drawn to scale, then they all will be too small and cannot be seen in the visualizations.

Flat-Earthers fail to realize that these are visualizations. They think the pictures are presented as real photos. Because we never see satellites like that, they concluded that it was a deception. In reality, these pictures are simply visualization, not actual photos.

In these measurements, we measured a 1000 gram calibration weight using a digital coffee scale. The first measurement was done in Jakarta, Indonesia, at about 80 m above sea level.  Because the calibration was also done with the same calibration weight at the exact location, then the scale also indicated 1000 grams. As for the air pressure, the phone stated 1002.2 hPa.

Then we traveled to Bandung, Indonesia, at about 750 m above sea level. Measurements gave us 999.72 grams and 929.3 hPa. The scale measured that the weight was slightly less, and the air was also less dense.

We repeated the first experiment to ensure that the measurement was not affected by the previous measurement or anything that occurred afterward (carry-over effect). It gave us the same number, 1000 grams. And the air pressure changed slightly to 1003.5 hPa.

The largest satellite is the ISS, about 109 m in length. The Earth is 12742 km across and 116900× the size of the largest satellite. For comparison, if a football field is 110 m long and the size of an ant is 3 mm, then a football field is 36667× the size of an ant.

If the ant is not visible in a photo of an entire football field, then a satellite in an image of Earth is even less visible.

https://www.youtube.com/watch?v=sPQ-tMoAHkY&ab_channel=NASAWallops
Why satellites aren't the same as balloons.

A different camera lens can produce a different shape of bokeh. Concentric circles (onion rings, shooting targets) usually result from aspherical lens elements. Polygonal shapes are due to the outlines of the lens’s aperture when stopped down. Donut-shaped bokeh is due to the obstruction by the secondary mirror in a mirror lens. The cat’s eye bokeh is caused by the cylindrical shape of the lens when the object is near the edge of the frame. The bokeh shape tells us more about the camera and lens than the intended objects.

Flat-Earthers invented wild assumptions to explain why stars and planets do not appear as they are supposed. The real explanation is more straightforward: these shapes are just bokeh, and they tell us more about their photography skills or the lack thereof.

Join the group chat: https://t.me/flatearthdebunkedchat

A light bulb is a vacuum inside, with a glass wall separating the inner vacuum and the air outside. Air cannot travel toward the lower pressure area inside the bulb because the glass wall exerts the normal force —or the Van der Waals force— to the air outside.

A pressure tank is a container designed to hold fluids at a higher pressure from the ambient pressure. It does that by having a barrier preventing the fluids inside from going out. However, when the tank is being filled in, there is a connection from the outside to the inside, and it is not entirely sealed. The air outside can move toward the higher pressure area inside the tank —the reverse from the usual situation— because a pump is exerting a force to the air particles.

Without a force affecting air particles, the air would move to a lower pressure area, like a vacuum. A barrier can provide the normal force that can prevent air from moving to a smaller pressure area. However, it does not have to be a normal force. Other forces can affect air particles, too, including gravity.

Sun glare is caused by the scattering of sunlight in the atmosphere. And internal reflections in the optical system can also cause it.

The intensity of sun glare is less than the strength of the light coming directly from the Sun, but it is still too bright for our eyes to distinguish it from the sun itself. It is the reason the Sun and its glare appear as a single bright object.

To observe the Sun without its glare, we have to reduce the exposure by using the in-camera exposure settings or using a solar filter. By eliminating the glare, we can observe that the sun’s size remains constant throughout the day.