De la relatividad de la inercia al universo cerrado

Searching for the field equations of general relativity, Einstein was confident these could naturalIy result in agreement with JVlach'sideas on the material origin of inertia. However, when, with the important assistance of the mathematidan Mareel Grossman, he was able '.;0find tensor field equations he was forced to struggle facing severa! problems to overcome the apparent ~lachian failure of his preliminary gravitation theory. Einstein's strategies to implement ivlach's 'relativity af inertia' included highly restrictive boundary conditions, limiting general covariance and, finally, modified dosed cosmology. This article surveys this entangled history.