BRILLIANCE Four new books put Einstein’s general theory of relativity in historic and scientific context.
Ferdinand Schmutzer/Wikimedia Commons
GETTING A GRIP ON GRAVITY Einstein's general theory of relativity explains gravity as a distortion of space (or more precisely, spacetime) caused by the presence of matter or energy. A massive object generates a gravitational field by warping the geometry of the surrounding spacetime.
Nicolle Rager Fuller
OLDER THAN IT LOOKS Some very old stars in the Milky Way, such as HE 0107-5240 (arrow), might be first-generation stars in disguise, a new study suggests.