Weird Earth. Donald R. Prothero
the dome of the sky and stars above it, and the moon and sun rotating in the sky above us, but he does not explain how this would create the phases of the moon or would explain eclipses, which are entirely impossible with his model.
When you argue with a flat-earther, a highly revealing moment is when they fall back on their cop-out “Oh, that’s just math and physics—I don’t believe in those.” In the documentary, Sargent says, “The reason why we’re winning against science is that science just throws math at us,” as if that were some mark of how smart he is and how he is beating science. This is behind much of their thinking: they are only capable of simple intuitive models and are typically math-phobic, so they refuse to do even the simplest calculations that would show why their ideas are impossible. By contrast, since the days of Isaac Newton, the reasons we know the earth is round are best understood by doing mathematical calculations that only make sense in a spherical globe and cannot be accommodated in a flat earth.
But the most revealing moment in the documentary is when the flat-earthers attempt to do experiments to prove their point. In both cases, the experiments actually show that the earth is round, and the flat-earthers refuse to accept the results:
One of the more jaw-dropping segments of the documentary comes when Bob Knodel, one of the hosts on a popular Flat Earth YouTube channel, walks viewers through an experiment involving a laser gyroscope. As the Earth rotates, the gyroscope appears to lean off-axis, staying in its original position as the Earth’s curvature changes in relation. “What we found is, is when we turned on that gyroscope we found that we were picking up a drift. A 15 degree per hour drift,” Knodel says, acknowledging that the gyroscope’s behavior confirmed to exactly what you’d expect from a gyroscope on a rotating globe. “Now, obviously we were taken aback by that. ‘Wow, that’s kind of a problem,’” Knodel says. “We obviously were not willing to accept that, and so we started looking for ways to disprove it was actually registering the motion of the Earth.” Despite further experimental refinements, Knodel’s gyroscope consistently behaves as if the Earth is round. Yet Knodel’s beliefs seem unchanged when discussing the experiment at a Flat Earth meetup in Denver. “We don’t want to blow this, you know? When you’ve got $20,000 in this freaking gyro. If we dumped what we found right now, it would be bad. It would be bad. What I just told you was confidential,” Knodel says to another Flat Earther in attendance.29
The second experiment was run by Knodel’s cohost on his flat-earth YouTube channel, Jeran Campanella. This experiment provides the ending for the film. As described in Newsweek,
Campanella devises an experiment involving three posts of the same height and a high-powered laser. The idea is to set up three measuring posts over a nearly 4 mile length of equal elevation. Once the laser is activated at the first post, its height can be measured at the other two. If the laser is at eight feet on the first post, then five feet at the second, then it indicates the measuring posts are set upon the Earth’s curvature.
In his first attempt, Campanella’s laser light spread out too much over the distance, making an accurate measurement impossible. But at the very end of Behind the Curve, Campanella comes up with a similar experiment, this time involving a light instead of a laser. With two holes cut into styrofoam sheets at the same height, Campanella hopes to demonstrate that a light shone through the first hole will appear on a camera behind the second hole, indicating that a light, set at the same height as the holes, travelled straight across the surface of the Flat Earth. But if the light needs to be raised to a different height than the holes, it would indicate a curvature, invalidating the Flat Earth.
Campanella watches when the light is activated at the same height as the holes, but the light can’t be seen on the camera screen. “Lift up your light, way above your head,” Campanella says. With the compensation made for the curvature of the Earth, the light immediately appears on the camera. “Interesting,” Campanella says. “That’s interesting.” The documentary ends.30
Even more revealing than the failure of their experiments and their reactions when they inadvertently demonstrate the curvature of the earth is the insight into the psychology of flat-earthers. Like many other conspiracy believers and cult followers, flat-eartherism is a fundamental belief system to them and a community, so flat-earthers cannot allow anything to change their minds. Otherwise, they will lose their sense of identity and group belonging as well as their feeling of understanding and controlling the world around them. As reported in Newsweek,
“Say you lose faith in this thing. What then happens to my personal relationships? And what’s the benefit for me doing that? Will the mainstream people welcome me back? No, they couldn’t care less. But, have I now lost all of my friends in this community? Yes. So, suddenly, you’re doubly isolated,” psychologist Dr. Per Espen Stoknes says in the documentary. “It becomes a question of identity. Who am I in this world? And I can define myself through this struggle.” “If I tried to go…” [flat-earther Mark] Sargent says in the documentary, contemplating the scenario described by Dr. Stoknes. “They would come and say, ‘Don’t, don’t do it.’ So I couldn’t, even if I wanted to.”31
How Do We Know?
One thing we have learned from this widespread skepticism of science and established reality is that we scientists and educators need to do a better job of conveying both the facts of science and the evidence of those facts to people. We need to describe and demonstrate the evidence why we know certain things to be true. As Neil deGrasse Tyson wrote, “The fact that there’s a rise of Flat-Earthers is evidence of two things. One, we live in a country that protects free speech. And two, we live in a country with a failed educational system…. Our system needs to train you not only what to know, but how to think about information and knowledge and evidence. If we don’t have that kind of training, you’d run around believing anything.”32
So how do we know that the earth is roughly spherical in shape?33 How could you tell for yourself without engaging in dangerous stunts like launching yourself in a homemade rocket? To answer these questions, we will not use observations from satellites, spacecraft, or aircraft, because flat-earthers believe that these are all hoaxes and part of a giant conspiracy.
1. Watch ships at sea: Even before the Greeks wrote about the spherical earth, ancient seafarers knew that if you watch a ship sail away to the horizon, the bottom hull of the ship vanishes first, followed by the mast and then the top of the ship (fig. 2.3). If it is sailing toward you, you see the masts first, followed by the hull as it gets closer. This only makes sense if the ship is sailing around the curve of the earth. Flat-earthers also have heard of this evidence, of course, and claim it is an illusion caused by the perspective on different objects. But this is not how perspective works. If an object is far away on a flat surface, it will get smaller, but the lower part will not vanish as it recedes; instead, all of it will get smaller but remain fully in view. This is true even if you go to a harbor and follow the ship using a telescope or binoculars to improve your distance vision. The ship will vanish from bottom to top, not just become smaller.
Figure 2.3. Medieval drawing of a ship at sea disappearing bottom first on the horizon of a curved earth. (Public domain.)
2. Look to the stars: As the ancients noticed, the constellations look different as you travel north and south in latitude on the earth. About 350 BCE, Aristotle was one of the first to record this observation. Traveling from Greece to Egypt, he could see the difference in the skies. As he noted, “There are stars seen in Egypt which are not seen in northern regions.” He realized that the earth was small enough that its curvature was apparent over that relatively short distance, “for otherwise the effect of so slight a change of place would not be quickly apparent.”34 The difference became even more obvious when the first European explorers traveled south of the equator and found a whole new sky full of unfamiliar stars and constellations. The Southern Cross, for example, cannot be seen until you travel south of the Florida Keys, yet it becomes the major constellation of