Flat Earth
I very much like the answer from Greg Scott. I think that hits the nail on the head for many flat Earth believers.
For others, the problem may be an inability to visualize the very large scale of the universe and how a big-enough spherical body is going to of course look and feel “flat” at the relatively small local scale.
To that I would add a failure of critical thinking and analytical reasoning. The arguments in favor of a flat Earth are pitifully flawed and the lack of thinking things through is profound. A couple examples:
- Flat Earth proponents have the amusing belief that an aircraft would have to continually keep pointing its nose down to avoid flying off into space — yet they fail to see that in the disk-shaped flat Earth (the U.N. azimuthal projection) (a) there would be no true east or west, (b) where the sun rose and set would be literally all over the map, and (c) airplanes would have to continually turn their noses north or south to keep going “west” or “east,” respectively.
- Flat Earth proponents could easily fund and mount an expedition to sail around Antarctica to prove their claim (based on the U.N. map) that it takes at least 24,000 miles to make the trip (minimum, roughly) or even up to some 78,000 miles per other flat Earth claims. The actual trip to circumnavigate Antarctica would be a fraction of that — around 11,000 - 12,000 miles, depending on how much you want to chart a course that “smooths out” the coastline. Why don’t flat Earth proponents make this simple, provable test? They had to add another layer of conspiracy — the U.N. supposedly patrols the southern seas to keep the truth-seekers out!
- There is a peculiar failure to understand even Galilean relativity, or how “level” and “flat” are functionally synonymous at the small scale of human life while “level” and “flat” are not at all equivalent at the actual scale of Earth, or how and why a Foucault pendulum does what it does, or why stars seem to “rotate” in opposite directions depending on which hemisphere you are in, or why artillery and riflery have to take Earth’s rotation (and curvature) into account to hit targets at certain distances and directions, and so on. Causes: failure of education, self-discipline, intellectual honesty, etc.?
I do find flat Earth propositions and conspiracy theories to be entertaining. They can be debunked any number of ways. However, they are beliefs, and as such they have insulated themselves from debate and reality.
A real challenge is how you persuade anyone of anything contrary to their views in an era when one’s own “lived experience” is a presumed “reality” and science is equated with suppression. Suppression of what? If science suppresses anything, it suppresses ignorance.
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The pressure gradient absolutely disproves the flat enclosed earth belief. If the earth had an enclosed system the air pressure would equalise, like it does in a balloon or car tyre. You do realise that Southern hemisphere compasses are different to Northern hemisphere compasses too dont you? The nonsensical flat earth idea makes lunar eclipses impossible, has no coherent explanation for sunrise or sunset, cant explain why people in Australia see different stars rotating around a different celestial pole to those in Europe, makes regularly flown direct flight routes and times impossible, has no map that reflects reality despite it being no more than a floor plan if the earth is flat, whilst the map they use has distances that don't make any sense at all, ignores the fact that in reality all navigation both maritime and aviation is based on a globe, but instead requires its adherents to believe in a massive overarching conspiracy involving millions of people from different countries over multiple centuries, lies about the Antarctic and the Antarctic treaty, and blindly believe in an edge no one in human history has seen, an ice wall that around the entire earth that avoids detection and an unseen dome that mysteriously lets meteorites through.
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I am sorry to disrupt your belief, but there is NO evidence to support the idea of a flat Earth, with an important exception. There is, however, about 2,400 years of solid, reliable, credible and cross-checked evidence supporting the idea that it is approximately spherical. In the last 400 years, the amount of such evidence has been increasing exponentially, and now arrives at the rate of Gb per hour at precisions of millimeters, across the entire planet, 24/7.
There is too much of it to go into here, but let’s take something simple. And deal with that important exception.
Is your head flat? I trust that it approximately spherical, like other humans. If we consider a human to be about 2 meters tall and standing on an Earth that has a radius of about 6,300 km, then if your head is about 0.15 m in radius (about 6 inches) the equivalent size of a person is about 0.05 µm (micrometers) tall. (This is about the size of a virus.) At this scale, a single skin cell (about 100 µm) is a mountain 4 km high. Imagine you are standing, reduced to that scale, on your own head. Each of these 4 km high mountains is also 4 km across, so there is a new mountain every 4 km. Do you think that your head is spherical or flat, based on your own observations?
In fact, your skin is far, far rougher than the surface of the Earth. Imagine a smoother skinscape. Even for a virus on your skin, is the shape of your head discernible? It’s the same for our very limited senses. That’s why the Earth seems flat, based on our sensory impressions. Unless we add some thinking and an attempt to deal with inconsistencies, that’s as far as we get in geodesy.
At a local scale, you can even do a fair amount of measurement and assume the planet is flat. It works for building most structures and a lot of local mapping. The planet is so large that we can do quite a bit of measurement before we start to find those inconsistencies. For example, if you can measure to about 1 mm for vertical height differences over about 100 m, you can measure the curvature of the Earth, as the ‘drop off’ from a horizontal plane is about 1 mm in the first 110 m. When we are doing vertical measurement, such as leveling, we build a series of routines into our work to allow that difference to cancel out. We simplify things to make lives easier.
Once you go beyond a local scale, the inconsistencies with a flat Earth get progressively larger, as far as measurements are concerned. For things like navigating ships and aircraft, a spherical model of the Earth is good enough, so we could say that once we have gone beyond the local scale and can dispense with the aforementioned important exception, we are into curved surfaces.
When we work with GNSS and large-scale mapping and its control, we need to allow for the Earth being an oblate ellipsoid of revolution. This scale is for US states and larger (if that means anything).
If we are worried about vertical location, we need to know about where the vertical datum is. (This used to be called ‘Mean Sea Level,’ but we dropped the term several decades ago as it is kinda meaningless.) This vertical datum is the geoid, and is a far more complicated shape that is modeled using spherical harmonics. This would be our best current estimate of the shape of the planet, at least as far as the ‘zero’ vertical was concerned.
So the shape of the Earth that we choose to use is a matter of scale and need as much as anything else.
As to evidence you can see yourself, you are looking for the inconsistencies in what is observed compared to what you’d expect for a flat Earth. If you live near the sea, you can watch how ships disappear over the horizon. You should see consistent behavior, although there are occasionally some interesting refraction effects, e.g., Fata Morgana. If you travel north or south, you should see the stars’ rising and setting points move south or north, and you can check that they rise in the same places over time at your home. These are observations consistent with a spherical Earth. If you have seen a number of lunar eclipses, you can see that the shadow of the Earth on the Moon is always circular, no matter the time (and hence the position of the Sun), so Earth always casts a circular shadow. The only shape that does this from all angles is a sphere.
If you climb a mountain, you see further the higher you go. This is consistent with a spherical Earth. BTW, you do not get a ‘curved down’ horizon, as if you intersect a sphere with a plane (the limit of how far would can see) you get a flat circle, and looking at the circle almost edge on, you won’t see any curvature. If you go higher again, in an aircraft, you will see further again. Even if you go into Low Earth Orbit you cannot see all of the Earth; even the ISS can only see about 3% of the Earth’s surface at any one time.
If you read about the Coriolis force, you will discover it drives significant aspects of weather and many other things, e.g., air and water movements around the Earth. It’s very much a product of a rotating spherical planet. If you read about gravity, you will discover that on a flat Earth, we would almost all be leaning, more as we got to the edge, and that we would not fall off the edge, but have to climb up and over it and then climb down the other side. ‘Falling’ would be rolling back along the ‘surface’ towards the middle point of the flat surface. Further, unless that flat surface was incredibly strong, it would tend to fall back under gravity and form an approximate sphere (Aristotle made this point in about 350 BC).
BTW, the two pictures you posted are artist created. They don’t represent anything other than someone’s pretty pictures. And yes, I have been to Antarctica, there is no Ice Wall and no guards to stop you getting there, the stars do revolve around the South Celestial Pole and in a clockwise direction, the Sun moves from East to West, is to the north and moves in a counterclockwise motion, and you cannot see Polaris when you are south of the Equator.
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I recently proved the Earth is not flat. I phoned somebody at 8' west in Ireland as the sun set at 4' west and the sun they could see was about 3 solar diameters above the horizon of the sea. Unless there is more than one sun the Earth cannot be flat. And there cannot be an infinite number of suns or it would appear straight, not round, and we would enjoy a changeless day. I just threw that one in because it sounds good, and makes your brain go funny. Thanks to my demonstration it does not take much effort to explain the result with the theory of a surface which bends downwards continuously as we travel towards the horizon. If I keep going the time must come when I collide seamlessly with my starting point. Glad I have cleared up that great mystery. ☺
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