  We study the Lorentzian version of the type IIB matrix model as a
nonperturbative formulation of superstring theory in (9+1)-dimensions. Monte
Carlo results show that not only space but also time emerges dynamically in
this model. Furthermore, the real-time dynamics extracted from the matrices
turns out to be remarkable: 3 out of 9 spatial directions start to expand at
some critical time. This can be interpreted as the birth of our Universe.
