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...

In 1908 Hermann  Minkowski improved Special Relativity Theorie by replacing the Lorentz transformation by his own differential formula. Einstein followed him because now the speed of the proper observer could vary. Later Einstein made use of Minkowski’s formula in his General Relativity. Another advantage was that the...

In his Theory of General Relativity, Einstein replaced the Lorentz transformation by the formula of his tutor Minkowski. What happens if we apply the Minkowski formula back into the Theory of Spécial Relativity? What are the differences? This article shows: the Minkowski’s formula doesn’t create the Twin- and Ehrenfest...

How do you interpret the equivalence principle of gravity and acceleration? Einstein said: standing in a hypothetical closed elevator, you cannot determine whether you hang still and feel the effect of gravity of a planet nearby , or you feel the same effect caused by the elevator accelerating out in space. What...