7 research outputs found
Relativistic Solenoids
We construct a general relativistic analogy of an infinite solenoid, i.e., of
an infinite cylinder with zero electric charge and non-zero electric current in
the direction tangential to the cylinder and perpendicular to its axis. We
further show that the solution has a good weak-field limit.Comment: 9 pages, 2 figure
Holographic Protection of Chronology in Universes of the Godel Type
We analyze the structure of supersymmetric Godel-like cosmological solutions
of string theory. Just as the original four-dimensional Godel universe, these
solutions represent rotating, topologically trivial cosmologies with a
homogeneous metric and closed timelike curves. First we focus on
"phenomenological" aspects of holography, and identify the preferred
holographic screens associated with inertial comoving observers in Godel
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 Godel universes has
many features in common with de Sitter space, suggesting that Godel 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 Godel universes in string theory. We
show that Godel universes are T-dual to pp-waves, and use this fact to generate
new Godel-like solutions of string and M-theory by T-dualizing known
supersymmetric pp-wave solutions.Comment: 35 pages, 5 figures. v2: typos corrected, references adde