Flat Earthlings
Nut and Geb
How much of your knowledge is
the result of direct experience? How
much of your knowledge comes from external sources, with trusted experts
informing you? How much of your
knowledge comes from posts on social media? In the so-called post-truth era
with dubious information promulgated, the question of ‘facts’ is continually
being reevaluated. Here, I used the
modern and ancient beliefs in a flat earth as a small window into knowledge,
culture, and experience.
A well-known dynamic of the
internet is the ease with which like-minded individuals can aggregate. Conspiracy theorists hold forth on
chemtrails, 9/11, the JFK assassination, and other topics, but for me the most
intriguing are the Flat-Earthers. There
is even a Flat Earth Society. In addition, a number of celebrities, including
Kyrie Irving, profess the belief. In
November 2017, The Boston Globe reported the strange case of a New Hampshire
native, Jason Torres, who, in his desire to prove that the earth was round,
ended up believing the opposite: that the earth is flat[i]. According to the Globe, he spends a large
amount of his time doing measurements in his quest.
The modern Flat-Earthers hold that
the world is a circular disk, with the north pole at the center, and the
farthest known territories are a ring of mountains in what the rest of us call
Antarctica. In their model, the sun
simply circles overhead in a path that gives darkness to some areas and light
to the others, depending on where it is in its orbit. To them, photographs of the earth from space
are all doctored and there is a massive conspiracy to present the earth as a
sphere.
Not surprisingly, popularizers of science like Neil DeGrasse
Tyson, and the UK’s Brian Cox, have fired back at the trend.
In a social media rant, Cox goes off on the flat earthers: “There is absolutely no basis at all for
thinking the world is flat. Nobody in human history, as far as I know, has
thought the world was flat.”[ii]
I point out that the second part of the statement by Cox is plain wrong. Let me ask the reader to introspect for a
minute and ask yourself if you have any direct experience of the earth as a
sphere. I’m not talking about seeing
photographs taken from the moon, which the Flat-Earthers claim are bogus; I’m
talking about direct experience.
It’s not crazy to think of the earth as flat, particularly if you don’t
travel very far. Some cultures may not have
even had a conception of the difference between a flat and a spherical
earth. Such a thought already requires
some degree of abstraction: which of two (or more) geometric models describes
the totality of the surface we inhabit?
Without this kind of abstract thinking, we cannot even contemplate the
question.
In ancient Egypt, the sky was viewed as a dome formed by the body of
the goddess Nut, whose feet were planted in the east and whose head and arms
extended to the west. Nut arched over
Geb, the god of the earth who lay prone.
There is a curious question for believers in a flat earth: how does the sun move from the west at sunset
to the east at sunrise during the night?
The modern Flat-Earthers would say that the circular path of the sun in
the sky accomplishes this. What about
the Egyptians? In one version of the
mythology, the sun journeys along the abdomen of Nut during the day, then she
swallows the sun in the evening, and she expels it from her high quarters at
dawn. In other versions of the
mythology, the sun journeys through the underworld to get back to the east.
Nut and Geb
In myths where the sun’s return path is through the underworld, the
idea that dead souls also inhabit this dark nether region has a certain logic
to it. In an Egyptian variant, Duat,
the underworld is a region where the sun (Ra) makes the return journey from
west back to east. The setting sun in
the west is often associated with death, and not surprisingly, the idea that
the dead inhabit the region where the sun journeys back to the east at night
would be compelling.
The first significant departure from mythologizing the cosmos was with
the ancient Greek philosopher, Anaximander, who opted for a purely physical
model. In his universe the earth was a
short cylinder floating in free space[iii]. On the flat surface of the cylinder all the
land of the world was surrounded by an encircling ocean. The sun and moon are part of separate wheels
in the sky, but tilted at an angle to the cylinder. In Greece, as in other temperate regions,
the path of the sun is inclined, so the tilted wheel model makes sense. With the sun modeled as a floating cylinder,
the return path of the sun to the east has a physical explanation rather than the
mythology of Ra journeying through the underworld.
Anaximander's model.
That was in 600 BC. The Pythagoreans (c. 500 BC) were likely the
first Westerners to conceive of a spherical earth as it was an abstract
geometric model where the surface did not have a boundary per se. Still, the spherical nature may not have
been evident, but voyages of significant distances to the north changed that. In particular, Pytheas of Massalia is said
to have sailed as far north as what is now Norway. With long voyages to the north, the apparent motions
of the stars, planets, the sun, and moon all change appreciably e.g. the
midnight sun that never sets. Pytheas
would have witnessed different motions of the sun and stars that can only be
explained by a spherical earth.
I have the good fortune to have traveled widely: as far north as
Iceland, as far south as Patagonia, and many points in-between, such as the
Marshall Islands, close to the equator.
Being an inveterate star-gazer, I’m always looking for star formations –
whether seeing the entrance of the Southern Cross when I approach the Equator,
or the appearance of Orion as ‘upside down’ from Patagonia. These are all visible reminders of the
spinning ball we inhabit. Taken one
step further, it forms the basis of celestial navigation.
In a course I teach, I ask my students to visualize the motion of the
stars and sun over the course of a night, and throughout the year from
different vantage points on the earth. We start with the motion of rising stars at
the equator, imagine the stars circling overhead at the poles, and then the
views from latitudes in between. It’s not an easy exercise to gain this
visualization, but when I then present the motion of stars and the sun in time
lapse videos, the students are able to identify roughly the latitude where the
video was taken and which direction they’re looking. Most people rarely engage
in this kind of home-brewed empiricism, and yet, it’s something that our
ancestors do.
While the motion of celestial objects as seen from widely varying latitudes
pretty much nails the question of the earth being round, observing the sphericity
of the earth on shorter distance scales can be challenging, but it is possible.
Although we may view the Flat-Earthers as unscientific, they do engage in a
kind of empiricism, as pointed out by the writer Lizzie Wade in an article she
wrote for the Atlantic[iv]. In the Globe article on Jason Torres
mentioned above, it describes his attempt to measure the curvature of the earth
by photographing Hull from Boston Harbor.
What he was hoping to see was some of the shoreline of Hull hidden by
water as it would be slightly under the horizon. In his account, he didn’t see an
effect. This is not terribly surprising
as Hull is only five miles from Boston Harbor, and the effect is fairly
small.
On the other hand, at distances of about seven or eight miles, the effect
of land disappearing under the horizon begins to become apparent. For example, from my house on Cape Cod facing
Nantucket Sound, the image of parts of Monomoy Island eight miles away are at
the point of being obscured over the horizon by the earth’s curvature. The long contiguous stretch of Monomoy
visually appears to be broken up into much smaller islets, as the low-lying parts
are obscured by the horizon while the higher parts protrude. Nantucket, being 20 miles away, is simply not
visible, although on clear nights, I can see the lights of Nantucket village
looming as light from the Village reflects off of dust in the atmosphere. The sweep of the lighthouse on Great Point
also looms in the distance, although the lighthouse itself is also over the
horizon.
This phenomenon of objects disappearing over the horizon is fairly
common and is well known to sailors. To me,
this raises a question: in the presence of objects disappearing over the
horizon, why did people not believe in a spherical earth well before Pytheas? Surely
sailors sailed far enough away from land for this to be apparent. Here is my speculative answer: we know that light
from near the horizon travels a considerable distance to reach our eyes, and
refractive effects (bending of light in the air) are common, often giving rise
to mirages. I can imagine that ancient sailors
might have interpreted the disappearance of low-lying land in the distance as a
mirage-related phenomenon. Moreover, at
distances of eight miles or more, where the effect might be apparent, objects
appear quite tiny, and the visual appearance might not have been discernable.
A
container vessel 'hull down' in the distance.
It is so far away that the hull underneath the containers is under the
horizon. This photo appears on the Flat Earth Society
website where they go to some length to attribute the phenomenon to refraction.
The modern Flat-Earthers use refraction to explain the disappearance of
objects over the horizon, and on this point, they may be invoking an argument that
may be quite old, and not completely inconsistent with personal
experience.
I know of at least two other simple experiments that an individual can
perform over short distances to demonstrate the curvature of the earth. Again,
these may have not been obvious to ancient peoples. I haven’t poured over the Flat Earth Society
website to see if they are aware of these, and if so, whether they have
explanations for them. Given the nature
of online conspiracy groups, I strongly suspect that they would have some
explanation if confronted with the experiments.
From the time of Aristotle onward, the Greek model of the universe had
a spherical earth at the center of the universe and celestial objects orbiting
around it. Curiously, this central to
the development of astrology as a means of augury, and the ‘rules’ were
described in detail by Ptolemy in Tetrabiblos (four books). I will not defend a spherical earth on the
basis of astrology, but will note that the sphericity of the earth is key to
its workings.
During the centuries after Ptolemy, astronomy and astrology were largely
intertwined and not separate endeavors as we see them today. In the 15th century, the
Portuguese employed astrologers to develop the schema for celestial navigation. They employed the tools of their trade: almanacs
of the positions of celestial objects, and instruments like astrolabes and
quadrants that measure the heights in the sky.
A spherical earth was absolutely critical for the this to work. Contrary to misconceptions, very few educated
people believed in a flat earth in that period, and voyages of any considerable
distance in the 16th century and beyond relied on celestial
navigation. In that era, a belief in a flat earth became
quite unsustainable – the trigonometric equations used to determine latitude
and longitude require a spherical earth.
This is not to say that the earth is a perfect sphere. By the 17th century, it became
evident that there was a bulge at the equator and a flattening at the poles due
to the earth’s rotation, and measurements by satellites launched in the 1960’s
and later measure other departures. Modern mapping and GPS measurements use two
models: a reference ellipsoid and a geoid.
The reference ellipsoid is a mathematical model that approximates the
surface of the earth and an idealized ellipsoid that captures some features
like the equatorial bulge. The geoid is
an irregular surface that takes into account the gravitational pull of
mountains and other features to help define a mean ‘sea level’ as an aid to
precision measurements.
Few people engage in celestial navigation or know what a geoid model
is. These are undoubtedly obscure topics for the average citizen, although the
man or woman on the street will gladly find their location with a cell phone
that relies on these things.
Returning to the ‘proof’ of a round earth, the most convincing to a
citizen willing to engage in a personal quest, like Jason Torres, is the motion
of celestial objects at different latitudes.
Sadly, in our era, you have to look far and wide to find a person who
can identify stars, much less visualize their motions. While I do not have much sympathy for the
modern Flat-Earthers, I can see how they could maintain their conspiracy.
[i]
Dugan Arnett, The Point of No Turn: For a dogged flat-earther, it’s a lonely new
world, Boston Globe, Nov. 29, 2017, p. 1.
loved your way of teaching, keep up the good work,
ReplyDeleteMany thanks!!
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