Civilizations could use gravitational lenses to transmit power from star to star

In 1916, famed theoretical physicist Albert Einstein put the finishing touches on his theory of general relativity, a geometric theory for how gravity alters the curvature of spacetime. The revolutionary theory remains foundational to our models of how the universe formed and evolved. One of the many things GR predicted was what is known as gravitational lenses, where objects with massive gravitational fields will distort and magnify light coming from more distant objects. Astronomers have used lenses to conduct deep-field observations and see farther into space.