Closed timelike curves in asymmetrically warped brane universes

by Heinrich Paes, Sandip Pakvasa, and Tom Weiler

We discuss causality properties of asymmetrically warped space-times and argue that such scenarios may allow for timelike curves which can be closed via paths in the extra-dimensional bulk. We find a metric where the null, weak and dominant energy conditions are violated in the bulk, but satisfied on the brane. Such scenarios are interesting, since in principle gravitons or gauge-singlet ("sterile") fermions propagating in the extra dimension may be manipulated in a way to test the chronology protection conjecture experimentally.

We have demonstrated the existence of closed timelike curves (CTC) for a rather generic asymmetrically warped metric. In addition, we have found a particular metric yielding positive energy density on the brane. A thorough discussion of whether CTCs in the observable universe are prevented by stable chronology horizons where the stress-energy tensor diverges, is beyond the scope of this work. We have confined ourselves to the pragmaticattitude that even if chronology is protected by some mechanism operative near the chronology horizon, it remains a highly rewarding effort to study the physics near this horizon. The CTC we have constructed is particularly interesting in this respect, since it is available to particles which have previously been hypothesized to propagate in the extra-dimensional 'bulk'. Such particles include the graviton and sterile (gauge singlet) fermions.

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Sites: Heinrich Paes, Sandip Pakvasa, Tom Weiler