a- The flat earth theories
Most people have known that the earth is a sphere for about 2,000 years
however a small minority still believes that it is flat. At the present
time it is not easy to deny that the earth is spherical as the pictures
taken from satellites show clearly its shape.
b- Why is the earth not in free fall in space?
According to some Hindu traditions the flat earth is held up by four big
elephants standing on top of a turtle. The obvious question is "how
does the turtle keep still?" An answer was that there are in fact a
large number -an infinity?- of these animals standing on each other!
c- Expanding earth theory
Before the theory of the plate tectonics became known, geologists explained
the separation of the supercontinents into the present landmasses by saying
that the earth was once a small ball that successively expanded over time.
d- Atlas
Greek mythology tells of Atlas, a strong Titan, who fought the Olympian
gods during the Titanomachy war. The Titans were defeated and, as a punishment,
Atlas was condemned by Zeus to stand at the edge of the earth and hold up
the sky for eternity.
e- Hollow earth theory
Plato wrote that enormous subterranean tunnels exist under the earth's surface.
In the 17th century the English astronomer Edmond Haley thought that the
earth is not hollow but is made of four habitable concentric spheres, each
one being illuminated by a luminous atmosphere and each has independent
magnetic poles. Later on the Swiss mathematician Leonhard Euler replaced
the multi-spheres theory b with a single hollow sphere containing a sun
600 miles wide. Later on in 1818, the American ex-army officer and businessman
John Cleves Symmes believed that there were apertures at the north and south
poles leading to the interior of the earth. To him the earth is hollow and
habitable within, containing a number of solid concentric spheres. In the
19th century the American doctor Cyrus reed Teed suggested that we live
on the inside of a giant sphere with, at its centre, a sun half light and
half dark to explain the sunrise and sunset. Even the German during the
Second World War explored the possibility that the earth is hollow.