Einstein published his theory of General Relativity (GR) in stages. Based on these publications, Karl Schwarzschild found two exact solutions in January and February 1916. However, on May the 11th of that year, Einstein published his official GR – with important changes effecting both of Karl’s exact...

Contrary to popular believe, there are many Schwarzschild Solutions. Karl himself found one to a mass-point and one to a sphere of in-compressible liquid early 1916. After Karl’s death Einstein made important changes in his  official publication: he abandoned his g = -1 requirement in a footnote. Nobody checked...

Einstein used a complicated set of tensors in his General Relativity. However in his writing in 1916 he used a Laplace operator, which can help us to determine the gravitational potential inside a sphere without having to go into his field equations. Many surprising results: The behaviour of clocks is in line with all...

Einstein’s General Relativity contains the Laplace operator of a sphere of incompressible liquid. It links the time-like solution (how fast does the clock tick) directly with the gravitational potential: no need for using tensor operations. He never applied it to the potential inside a sphere. This article is doing...

The cause of the high temperature of the inner core of the earth is currently thought to be radioactive decay and residual heat. This article provides a different explanation: Energy conservation. Imagine a tunnel through the earth and calculate the potential energy of a molecule at the surface and in the core. You...