Phase transition and inflationary universe model

The inflationary universe scenario is reviewed. The usefulness of this scenario in solving the basic problems of the big bang model is reviewed, and the original inflationary model and its difficulties are recalled, including the nucleation of bubbles and progress of phase transition, black hole and wormhole formation, the percolation of bubbles, and the fractal structure of the universe. The new inflationary model is discussed, including the Coleman-Weinberg potential, gravitational effects on phase transition, the dynamical evolution of Higgs fields in the SU(5) model, the primordial inflation model, and the chaotic inflation model.