  We study the matter produced in heavy ion collisions assuming that this
matter is strongly interacting and employing AdS/CFT correspondence to
investigate its dynamics. At late proper times we show that Bjorken
hydrodynamics solution, obtained recently by Janik and Peschanski using
gauge-gravity duality [hep-th/0512162], can be singled out by simply requiring
that the metric tensor is a real and single-valued function of the coordinates
everywhere in the bulk, without imposing any constraints on the curvature
invariant. At early proper times we use similar strategy to show that the
energy density approaches a constant as proper time goes to zero. We therefore
demonstrate that the strong coupling dynamics incorporates the isotropization
transition in heavy ion collisions. By matching our early-time regime with the
late-time one of Janik and Peschanski we estimate the isotropization time at
RHIC to be approximately 0.3 fm/c, in good agreement with results of
hydrodynamic simulations.
