The modern flat-earth movement began with Samuel Rowbotham in the 19th century. Rowbotham’s primary evidence that the earth is flat was his famous Bedford level experiment. Rowbotham stationed himself eight inches above the water at one end of the Bedford level and watched a small boat depart six miles. Rowbotham reasoned that if the earth is a sphere having 25,000 miles circumference, the bottom of the boat would have begun to be blocked by the earth’s curvature when it had reached one mile and that the entire boat ought to have disappeared well before reaching the end of the Bedford level six miles away. Since Rowbotham saw the boat the entire way, he concluded that the earth is flat. As I have explained before, Rowbotham failed to account for atmospheric refraction. Nevertheless, many modern flat-earthers have conducted similar experiments to show much the same thing that Rowbotham claimed he saw at the Bedford level. Current flat-earthers have the advantage of using modern electronic cameras with tremendous zoom capability to document their claims. Of course, flat-earthers continue to exclude the presence of atmospheric refraction, or when they acknowledge its existence, flat-earthers invoke atmospheric refraction in reverse.
There have been numerous examples of these experiments posted on the internet. However, in late 2019, flat-earthers generally began to rally around what they call “the black swan photograph” (Figure 1). This image was taken from a video posted by a flat-earther on his YouTube channel on October 25, 2016. Why it took flat-earthers three years to take notice of this video is not clear. As you can see in the photo, Platform Hillhouse on the right in this photo is 6.21 miles from the place the video was made, while Platform Habitat on the left is 9.41 miles from where the video was made. The video was made at water’s edge, only a few feet above the water. From this distance and the height of the observer, the earth’s curvature ought to produce noticeable blockage of the lower parts of either platform, with more of Platform Habitat being blocked due to its greater distance. There appears to be no blockage of either of the platforms, and one can readily see that the horizon is beyond the two platforms. Taken at face value, this single image would seem to constitute evidence disproving the earth is a sphere having 25,000 miles circumference. Flat-earthers argue that this view is expected on a flat earth, so they conclude that the earth must be flat. Let’s unpack this.
Why Call It “the Black Swan?”
First, why do flat-earthers call this “the black swan photo?” Most swans are white, so after one has examined many white swans, it is easy to reach the generalization that all swans are white. Such a conclusion is warranted with inductive reasoning, where one makes conclusions in the general case based upon many specific cases. Science is based largely on inductive reasoning, so this sort of approach often happens in science. Therefore, one might formulate the statement “All swans are white” as a hypothesis. How does one go about testing such a hypothesis? One would continue seeking out more swans to examine. With each white swan one encounters, the more confidence one has that the hypothesis is true. What would it take to disprove this hypothesis? One need find only one swan of a different color, say black. A single black swan would disprove the hypothesis. This is why “proof” in science is a bit different in deductive logic and the way we normally use the word. Philosophers of science often say that in science we don’t prove anything with 100% certainty but that we can disprove hypotheses with 100% certainty. Consequently, scientific concepts must have the possibility of being falsified. Good scientists spend much time trying to disprove their ideas. When various tests fail to disprove those ideas, the more confidence we have that our ideas are true. Flat-earthers seem to understand at least part of this approach, which is why they latched onto this photograph, calling it “the black swan,” thinking that it disproves the earth is a globe. Of course, they are wrong about that.
Flat-earthers trumpet this photo and others like it, claiming that such observations are everyday occurrences. They aren’t, as the original video linked above makes clear. The video began with several images of ships and other objects with their bottoms obscured by the horizon, with more of the objects being obscured with increasing distance, exactly as expected on a globe earth. At 0:22, this text appears in the video:
“Most days, normal visibility of platforms and boats, will appear they are behind the horizon, curvature of earth.”
Here the video maker admits that there is abundant evidence that the earth is a globe, though he doesn’t think the earth is a globe. At 0:44, the video starts the recording made at water’s edge, eventually zooming in on the two platforms, freezing this image (Figure 2) at 1:02. Notice that the horizon is in front of the two platforms, blocking view of part of the bottom of the platform on the right and much more of the platform on the left. This is what we expect to see if the earth is a globe.
At 2:07, this text appears in the video:
“Once in a while, not very often, there will be days when conditions are right to see full image.”
At 2:13, this text fades, followed by another video taken on a different day. This one eventually zooms onto the two platforms. The famous black swan photo is captured at 2:43 in the video. Again, the video maker (a flat-earther) admitted that most days the images one sees of these platforms indicate that the earth is a globe and that it is rare when the images indicate that the earth is flat. This is cherry-picking of data at its worst. The fact that flat-earthers endlessly promote this and similar photos as the norm demonstrates that flat-earth arguments are fundamentally dishonest.
Atmospheric Refraction Properly Understood
The comments in the original video discussed here several times alluded to atmospheric refraction, suggesting that it was refraction that caused the water between him and the platforms to rise in the second photo. This has atmospheric refraction backward. Examine the two photos carefully. Notice that the first photo (the black swan) shows much distortion in the more distant platform. The crane off its left side is bent and wavy (this is better seen around 2:40 in the video). There also is some compression in the more distant platform. These are tell-tale signs of atmospheric refraction. But the second photo shows no such distortion, indicating that atmospheric refraction, which is always present, was much less the day that photo was taken. And keep in mind, by the video maker’s own admission, days with little atmospheric refraction are far more common than the days with great atmospheric refraction. One critic of the flat-earth movement has done a detailed computation of atmospheric refraction on a globe earth to explain the black swan photograph. He further showed that to produce the black swan image on a flat earth would require conditions that are physically impossible, and it would not produce the observed distortions.
The black swan photo and other similar images commit the informal fallacy of cherry-picking data. Once again, a major flat-earth claim turned out to be false. There are many other examples of false claims made by flat-earthers. The problem is that there is no quality control within the flat-earth movement. A flat-earther makes a false claim, perhaps unknowingly. Without submitting the false claim to scrutiny, other flat-earthers simply repeat the false claim, and the false claim rapidly spreads throughout the flat-earth movement. Of course, once flat-earthers have repeated a false claim often enough, it is very difficult to get many of them to recognize that a claim is false. If they were to recognize this, it would seriously undermine their notion that the earth is flat. This is ironic. Flat-earthers often attempt to discredit anything that NASA produces (such as photos of earth from space) by noting that NASA is a government agency. Flat-earthers ask if the government officials or agencies have ever lied to the public. The obvious answer is yes, whereupon flat-earthers argue that if since the government has occasionally lied, then one cannot trust anything NASA says. But flat-earthers never apply that standard to their own movement. There are many lies circulating within the flat-earth movement, yet flat-earthers remain steadfast in their belief the earth is flat.