The idea of a spherical Earth has been around
for many years and was accepted due to the
numerous proofs supporting it, including pictures.
There are people, however, who choose to disregard
all that and support the concept of a flat
Earth, basing their assumptions solely on
observations and conspiracy theories.
Instead of trying to prove the Earth is round,
let's investigate and test the flat Earth
model, and see if it accounts for the mundane
occurrences that we've grown accustomed to.
Flat earthers believe the Earth to be a disc
with the Sun and Moon revolving above it as
illustrated in this simplified drawing.
They claim the Sun shines light into a spot
and that is how we have day and night cycles.
Furthermore, this model even explains how
we have seasons: the Sun moves closer and
farther away from the centre of the disc,
or the North Pole as we know it: e.g. when
the Sun follows the red circle we have summer
in the northern hemisphere, probably because
the Sun is closer and that means more heat.
It even explains the constant daylight during
summer at the North Pole and the complementary
seasons between the two hemispheres.
So far so good, but why does the Sun shine
into a spot?
It is also spherical in the FE model, so why
does it only radiate in a cone?
Since the Sun's spot doesn't reach the Moon,
but we clearly see it at night, some flat
earth supporters claim it has its own light
source.
Then how are the Moon phases explained?
Since the model doesn't offer any answers
to these questions, we will disregard them
for now.
One thing that it does explain, however, is
sunrise and sunset.
Flat earthers claim it happens because the
sun fades into the vanishing point.
That is the point at which the perspective
projections of parallel lines appear to converge.
Looking at the 2D road, we can change the
perspective to give the impression of a third
dimension.
Even though the sides of the road are parallel,
to give the picture depth, they converge into
the vanishing point.
The condition is that the perspective lines
form an angle of less than one minute of an
arc or 0.016 degrees at the observer, which
is, of course, very small.
Let's apply this theory to the FE and see
how far should the Sun be to merge with the
horizon for an observer on the FE.
So we tilt the disc for a 3D perspective and,
since the model gives the height of the Sun
to be 5000 km, we can build a simple trigonometric
model and calculate the distance.
So we set theta = 1 minute of an arc and,
by applying the sine, the required distance
turns out to be roughly 17 million km.
The Sun then has to leave the surface of the
Earth, so the model would look something like
this, or, seen from above, with the distance
being 1500 times larger than the diameter
of the FE, so it is by no means a good explanation.
Furthermore, even if the vanishing point could
explain sunrise and sunset, the observer would
see the Sun reducing its size down to a dot,
even before it merges with the horizon.
Flat earth believers have a counter-argument:
the Sun maintains its size due to some atmospheric
magnification, because it is evident that
the Sun doesn't disappear into a spot, but
gradually sinks into the horizon.
If this picture is explained by the vanishing
point theory, then because the apparent distances
at the vanishing point are proportional to
the real ones, the diameter of the Sun must
be larger than the distance to the surface
of the Earth, which is clearly not true.
Other "globe busters", such as Rob here, believe
the sunset to be explained by the so-called
"atmospheric lensing effect" due to atmospheric
refraction.
He tries to prove this by placing a lens in
front of a camera and, by moving the paper
back and forth, he shows how the drawing of
the Sun seems to sink, such as it happens
at sunset.
This is what his experimental setup looks
like.
To understand whether or not this is applicable
on the flat Earth, let's firstly understand
how he did his experiment: we have a lens,
the principal optic axis and the focal point
F.
We now place an object and construct its image
based on simple optics principles.
We proceed to add the camera on the right-hand
side and, if we move the object farther and
closer from the lens, we notice the image
sinking and rising.
Now, I can't imagine a way this could be applied
on the flat Earth; maybe something like this,
which would lower the Sun's apparent position,
but let's face it, there is a lens at the
North Pole.
In actuality, even if the Earth were flat,
atmospheric refraction occurs because the
atmosphere is denser at ground level than
at higher altitudes.
To illustrate this, we slice the atmosphere
into four parts and study the refraction of
light as it goes through the slices.
As we can see, the sunray is bent downwards,
just like Rob agrees.
This, however, doesn't bode well for him,
because if the light is bent downwards, that
means the Sun's apparent position would be
even higher in the sky, and not lower, so
it basically works against the proposed model.
(Atmospheric refraction is more complex than
it was briefly described here, so it will
be the main topic of a future video, in which
I will investigate if it can explain the Sun
shining light into a spot.)
We've then reached what mathematicians call
a null hypothesis, so the vanishing point
and atmospheric lensing cannot explain sunrise
and sunset on a flat Earth.
