Ferreira (Astrophysics/Univ. of Oxford; The State of the Universe: A Primer in Modern Cosmology, 2006, etc.) writes an enthusiastic and comprehensible popular account of how Albert Einstein’s Theory of Relativity continues to generate new knowledge as well as hints of more secrets to be revealed.
Einstein’s Theory of General Relativity may be the greatest discovery in science. It’s the key to understanding the history of the universe, the nature of time, stars, galaxies and matter itself. With the dramatic 1919 announcement confirming the theory’s prediction that gravity bends light rays, Einstein became a media superstar, and physicists began a search for other predictions that continues to this day. Everyone during that time, Einstein included, assumed that stars and galaxies drifted at random. Several physicists pointed out that his equations indicated an expanding universe. Reluctantly, Einstein finally agreed. Others calculated that when a large, aging star collapses, gravity shrinks it into an infinitely dense point outside of time and space: a black hole. However, Einstein never accepted that. During the 1920s, many physicists turned their attention to quantum mechanics and nuclear physics, which, unlike relativity, had vivid consequences. Only with the 1950s did a new generation return to the research. Simultaneously, astronomers began discovering phenomena that required relativity, including quasars, neutron stars, gravitational lenses, dark matter, energy and black holes. The perfection of Einstein’s theory remains; none of its predictions have been proven wrong, but the stubborn refusal of gravity to unite with all other natural forces remains a frustrating problem.
Ferreira does not downplay relativity’s complexity and avoids the easy route of oversimplifying it into a cosmic magic show. The result is one of the best popular accounts of how Einstein and his followers have been trying to explain the universe for decades.