In her new book Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos, Priyamvada Natarajan ’91, SM ’11 tells the stories of Einstein’s troubles with gravity, an expanding universe, and dark matter. For Natarajan, a professor of physics at Yale University, Einstein is just one of a cast of characters in 20th century astronomy and cosmology whose struggles are at times amusing and at other times most inspiring.