  The general relativity is the base for any exact evolutionary theory of large
scale structures. We calculate the universal 2+1-dimensional plane equations of
gravitational field in general relativity. Based on the equations, the
evolutions of disk nebula are discussed. A system of nebula can form binary
stars or single star for different conditions. While any simplified linear
theory forms only a single star system. It is proved that the nonlinear
interactions are very general, so the binary stars are also common.
