This is a follow-up to my post How we can know the earth is a ball without relying on modern science or traveling long distances?.

It is well-known and easily observable by the naked eye (even by a single individual if they use modern travel) that the stars appear to rotate counterclockwise in the Northern Hemisphere and appear to rotate clockwise in the Southern Hemisphere. Less often discussed but perhaps even more interesting is the fact that on the Equator itself, one can observe stars moving in either direction depending on whether one is facing north or south. Additionally, one can observe stars that pass directly overhead traveling from east to west. Recall that the sun and stars appear to move together, with their motion being only slightly different (which can be perceived over the course of days or weeks but not in real time). Again, this is consistent with a spheroid earth, whether it be within the currently accepted scientific model or within ancient cosmology such as Aristotle’s.

Based on what we can observe with our own eyes, a flat earth cannot be floating in space surrounded by stars as in reality, nor can it be surrounded by a celestial sphere that holds the stars and rotates around the earth as in Aristotelian cosmology. In both cases, we would lose the stars’ apparent clockwise rotation in the Southern Hemisphere. Consequently, actual flat earth models usually place the stars in a disk or dome above the earth. However, in order to get the motion correct with this positioning, flat earthers have to introduce some bizarre ad hoc explanations.

On both the flat earth and the globe earth, “north” and “south” are not single directions in space but rather depend on your location on the earth. On the globe earth, north and south each point to a single location, namely the poles. On the flat earth, however, only north points to a single location, since there is only one pole; south is then defined as the direction opposite north, which points “outward” in all directions.

Now, I want to emphasize that it is technically not possible to have truly irrefutable proof of any scientific fact. What we see in the case of flat earth and star trails is that rescuing the “theory” requires a complicated explanation that is not corroborated by our everyday experiences of smaller-scale, easily observable phenomena. The globe earth, on the other hand, makes sense geometrically with what we observe in the sky as well as how we understand small spherical objects and our everyday experience of light.

The theory of the Electromagnetic Accelerator (EA) states that there is a mechanism to the universe that pulls, pushes, or deflects light upwards. All light curves upwards over very long distances. The Electromagnetic Accelerator has been adopted as a modern alternative to the perspective theory proposed in Earth Not a Globe.

Bishop 2023

How do we know it’s not the electromagnetic accelerator?

This, unfortunately, moves past what most people can observe firsthand.

1. We can fire lasers very precisely over long distances

The actual best example of this is experiments conducted using reflectors placed on the moon; but of course, flat earthers wouldn’t accept this evidence. This type of experiment can also be conducted on the earth’s surface however, and no deflection of light has ever been detected. Note that the flat earthers’ argument is that this effect can’t be seen in everyday life because it happens over long distances, but flat earthers deny astronomically large distances. In other words, the sun is not very far away, so the effect of light being deflected upwards should be measurable if it exists.

2. Quantum mechanics and general relativity preclude it

Since this line of evidence comes from math, it too would be unacceptable to flat earthers. That being said, quantum electrodynamics (QED) and general relativity are two of the most successful theories in science, providing very precise and accurate predictions that are used in real world technologies like satellites and electronics.

QED says that, barring any sort of interaction, light must follow the shortest path. Experimentally, the effect of an electromagnetic accelerator would be too slight to be detected over “quantum” distances. The theory itself, however, is totally wrong if light doesn’t follow the shortest path.

Relativity, too, states that light must follow the shortest path or geodesic through spacetime. This is different from following a straight line because spacetime can be warped by gravity, but most of spacetime is “flat” so that light does follow a straight line. In fact, because of the gravity of the earth, light should be deflected downwards if anything.

In summary

Ultimately, Occam’s Razor is probably the best reason to reject flat earth explanations of star trails. We simply don’t have experimental evidence for anything like light deflecting upwards. The mainstream scientific explanation matches what we know about small-scale geometry and is consistent with what humans have believed since ancient times. I don’t think this is a slam dunk like lunar eclipses, but it is very strong evidence that the earth is spheroid and rotating.

References and further reading

Bishop, T. (2023). Electromagnetic Acceleration. The Flat Earth Wiki. https://wiki.tfes.org/Electromagnetic_Acceleration

Raymond, D. (N.D.). 3.5: Fermat’s Principle. Radically Modern Introductory Physics Text I. LibreText. https://phys.libretexts.org/Bookshelves/University_Physics/Radically_Modern_Introductory_Physics_Text_I_%28Raymond%29/03%3A_Geometrical_Optics/3.05%3A_Fermats_Principle

Wikipedia. Geodesics in general relativity. https://en.wikipedia.org/wiki/Geodesics_in_general_relativity