NINETY-FIVE per cent of the universe is made of invisible stuff: the dark matter that holds the galaxies together and the dark energy that causes space to expand at a quickening pace. There is no shortage of theoretical candidates for these elusive ghosts. But how are astronomers to look for things that can鈥檛 be seen?
That鈥檚 where 鈥淓instein鈥檚 telescope鈥� comes in. It鈥檚 a term gives to gravitational lensing, the process by which a massive object distorts light that is streaming by, producing spectacular optical illusions in the sky and revealing the presence of unseen masses. In this highly informative book, Gates offers clear, accessible explanations of how gravitational lensing can be used to solve the biggest mysteries of the universe 鈥� first by using luminous matter to ferret out the dark matter, then by using the cosmic web of dark matter itself as a lens to probe dark energy and the very structure of space and time.
W. W. Norton
