Some people believe that the earth is flat and there’s a holes at the poles.

Flat Earth and Hollow Earth


Some people still believe that the earth is flat.

And a few believe that the earth is hollow. Such people are an easy target. There are all sorts of evidence that the earth is round, but not hollow, including common sense.
Flat Earth

In Columbus' Mistake I said this:
Columbus obviously knew that the world was round. Later, Magellan's ships sailed all the way around the earth. That proved that the world was round. But that had already been proved, back in Greek times. Most educated people knew that the world was round. The most convincing proof was that you could see the earth's shadow on the moon, during a lunar eclipse. During partial eclipses (and at the beginning and end of a total eclipse) the edge of the earth's shadow is always round, a portion of a circle. For this to happen every time, from all angles, the earth would have to be a sphere.

The way that a ship disappears over the horizon, long before it would appear to be a dimensionless point, was another strong piece of evidence showing that the earth was round.
Eratosthenes' measurement, whether it was accurate or not, was a further proof that the world was round.
Similar to Eratosthenes' observation is the fact that people at different latitudes see different constellations at night. You can measure your latitude by measuring how far the North Star (or the Sun) is above the horizon. People south of the equator cannot even see the North Star, as it is below the horizon. The stars could have been used to measure the size of the earth, in the same way that Eratosthenes used the sun. This would be a somewhat sounder measurement, as the stars are much farther away than the sun is.
The only reason that people might doubt that the earth is round is that it is huge, and it looks flat locally. A person's first impression is that it is flat. Consider an ant, on a fully inflated basketball, who thinks that the basketball is flat. Upon seeing the evidence of roundness, a few people have argued that maybe light is bent in weird ways, so that a flat earth may show evidence of being round. Such a theory has to be bizarre and elaborate, as well as being stupid.

Hollow earth


Well, how about a hollow (round) earth? Some strange people believe that there are huge holes at the poles, through which UFOs, or fairies, or demons travel onto the Earth. And of course there is some gigantic cover-up.
A huge hollow earth would collapse under its own weight. It would collapse into a round, solid earth, with a molten core, actually. Newtonian physics dictates that. You can calculate the mass of the earth, with a little elementary physics, if you feel like it. And you will find that the earth is roughly as dense as molten iron. It is not empty space; it is molten iron (mostly).

Hollow universe

I see that there are some people who believe that the earth is hollow, and that we live on the inside. For these people, the entire visible universe is also inside the earth. The laws of physics and math become amazingly distorted in order to make the situation appear to be that we are on the outside of the earth. As bizarre as this idea sounds, it is impossible to disprove. The only thing against such a hollow earth is that it is ridiculously complicated compared to the real, relatively uncomplicated universe. That makes the choice easy for scientists. The real universe is much much more likely to be true.

posted by: omar kodah