Towards supersymmetric cosmology in M-theory

We present a new solution in the heteotic M-theory in which the metric depe nds on (cosmic) time. The solution preserves N = 1 supersymmetry in 4 dimen sions in the leading order of the kappa(2/3) expansion. It is the first exa mple of the time-dependent supersymmetric solution in M-theory on S-1/Z(2). It describes expanding 4-dimensional space-time with shrinking orientifold interval and static Calabi-Yau internal space, (C) (C) 2000 Elsevier Scien ce B.V. All rights reserved.