Product Description: This work was conceived as an introduction to global differ­ ential geometry. It assumes known only the elements of classical differential geometry and Lie groupst. Some theorems are admit­ ted without proof, but in the majority of cases detailed proofs are given...read more

Product Description: For seventy years, we have known that Einstein's theory is essentially a theory of propagation of waves for the gravitational field. Confusion enters, however, through the fact that the word wave, in physics, implies sometimes repetition and sometimes not...read more