Wave packet in quantum cosmology

We examine in detail the fundamental problems in quantum cosmology concerning (a) the introduction of time, (b) probability interpretation, and (c) the emergence of a classical universe in the quantum framework, all of which are intimately interconnected. This study leads us to propose a simple Friedmann-Robertson-Walker-type minisuperspace model, in which issues (a)--(c) listed above are successfully solved. The model, which includes a massive and a massless scalar field, is of cosmological interest as well, exhibiting inflationary behavior in the early stage of the expansion. A possibility of an intriguing quantum structure in the region of a small scale factor is also noted.