Weak gravitational lensing

We review theory and applications of weak gravitational lensing. After summ arising Friedmann-Lemaitre cosmological models, we present the formalism of gravitational lensing and light propagation in arbitrary space-times. We d iscuss how weak-lensing effects can be measured. The formalism is then appl ied to reconstructions of galaxy-cluster mass distributions, gravitational lensing by large-scale matter distributions, QSO-galaxy correlations induce d by weak lensing, lensing of galaxies by galaxies, and weak lensing of the cosmic microwave background. (C) 2001 Elsevier Science B.V. All rights res erved.