physical explanation of the planets’ place in the heaven is one of the principal questions in the ancient astronomy which the authors of hay?a (cosmology) works tried to find an answer for it. their opinion is in fact a compilation from aristotle’s “fifth element” theory and ptolemy’s “prisms” theory. aristotle’s fifth element theory assumes that the substance of the heavens is different from t...

An attempt is made of giving a self-contained introduction to holomorphic ideas in general relativity, following work over the last thirty years by several authors. The main topics are complex manifolds, two-component spinor calculus, conformal gravity, α-planes in Minkowski space-time, α-surfaces and twistor geometry, anti-self-dual space-times and Penrose transform, spin-3/2 potentials, heave...