The origin of galaxies: A review of recent theoretical developments and their confrontation with observation

The subject of Galaxy Formation has advanced considerably during the past decade. On the theoretical side two theories in particular have been developed to the point where confrontation with observation will be possible; these are the "Gravitational Instability Picture" and the "Cosmic Turbulence Theory." These theories are discussed at some length here, with particular attention to the question of the origin of cosmic angular momentum and the nature of the initial conditions. There is now a considerable body of data on galaxies; the problem is in deciding which kind of observation is most relevant to understanding the origin of galaxies. Throughout the review an attempt is made both to put the present research in its historical perspective and to stress the possibilities for future advances towards the goal of understanding the origin of cosmic structure.