Theory of island of universes
The theory of island of universes is the conception of stellar systems scattered through the ocean of space. The basis of the theory were introduced by Wright and Kant who developed further Wright's speculations. Wright believed the stars are not scattered indefinitely through the universe, but they rather form a limited system, isolated in space. This stellar system is like disk or coin, i.e. relatively flat, and the sun is near the centre. Then he carried his speculations still further as the notion of just a single stellar system, alone in the ocean of space, was not acceptable to his sense of proportion. He dreamed of a universe populated by innumerable similar stellar systems, separated by vast intervals and regarded faint cloudy patches in the sky, known as nebulae, as visible evidence that such neighbouring systems exist. According to M.M. Capria The Island Universe Theory is the view that nebulae, called later the galaxies, were external to Milky Way and in fact were systems similar to it.