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Rotating Squeezed Vacua as Time Machines
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作者 S. Al Saleh L. A. Al Asfar A. Mahroussah 《Journal of Modern Physics》 2016年第3期304-311,共8页
Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticit... Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry, but because of violation of ANEC, the Cauchy horizon lies outside the system unlike Kerr blackholes, giving more emphasis on whether spacetime is multiply connected at the microscopic level. 展开更多
关键词 Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s) because they have a negative energy density. When treated as a perfect fluid rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry but because of violation of ANEC the Cauchy horizon lies outside the system unlike Kerr blackholes giving more emphasis on whether spacetime is multiply connected at the microscopic level.
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A Type D Non-Vacuum Spacetime with Causality Violating Curves, and Its Physical Interpretation
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作者 Faizuddin Ahmed 《Communications in Theoretical Physics》 SCIE CAS CSCD 2017年第12期735-740,共6页
We present a topologically trivial, non-vacuum solution of the Einstein's field equations in four dimensions,which is regular everywhere. The metric admits circular closed timelike curves, which appear beyond the ... We present a topologically trivial, non-vacuum solution of the Einstein's field equations in four dimensions,which is regular everywhere. The metric admits circular closed timelike curves, which appear beyond the null curve, and these timelike curves are linearly stable under linear perturbations. Additionally, the spacetime admits null geodesics curve, which are not closed, and the metric is of type D in the Petrov classification scheme. The stress-energy tensor anisotropic fluid satisfy the different energy conditions and a generalization of Equation-of-State parameter of perfect fluid p = ωρ. The metric admits a twisting, shearfree, nonexapnding timelike geodesic congruence. Finally, the physical interpretation of this solution, based on the study of the equation of the geodesics deviation, will be presented. 展开更多
关键词 exact solution anisotropic fluid closed timelike curves wave propagation and interactions
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