Holographic protection of chronology in universes of the Gödel type

We analyze the structure of supersymmetric Gödel-like cosmological solutions of string theory. Just as the original four-dimensional Gödel universe, these solutions represent rotating, topologically trivial cosmologies with a homogeneous metric and closed timelike curves. First we focus on the “phenomenological” aspects of holography, and identify the preferred holographic screens associated with inertial comoving observers in Gödel universes. We find that holography can serve as a chronology protection agency: The closed timelike curves are either hidden behind the holographic screen, or broken by it into causal pieces. In fact, holography in Gödel universes has many features in common with de Sitter space, suggesting that Gödel universes could represent a supersymmetric laboratory for addressing the conceptual puzzles of de Sitter holography. Then we initiate the investigation of “microscopic” aspects of holography of Gödel universes in string theory. We show that Gödel universes are T dual to pp waves, and use this fact to generate new Gödel-like solutions of string and M theory by T dualizing known supersymmetric pp-wave solutions.