Daintith, John, and John O. Clark, eds.The Facts on File Dictionary of Physics. 3rd ed. Facts on File, 1999. Concise definitions covering almost everything in the field of physics.
Gamow, George, and Russell Stannard.The New World of Mr Tompkins. Cambridge University Press, 2001. Updated version of a classic introduction for the lay reader to 20th-century discoveries in physics.
Chandrasekhar, B.S.Why Things Are the Way They Are. Cambridge University Press, 1997. A non-technical translation of the great achievements of physics, including quantum theory.