GÖDEL-TYPE UNIVERSES IN f(T) GRAVITY
GÖDEL-TYPE UNIVERSES IN f(T) GRAVITY
复制标题
DOI：
10.1142/s0218271812500745
复制
发表时间：
2012-03
影响因子：
2.2
通讯作者：
Dillon T. Liu;Puxun Wu;Hongwei Yu
中科院分区：
文献类型：
--
作者：
Dillon T. Liu;Puxun Wu;Hongwei Yu
通过考察在哥德尔型度规中封闭的类时曲线存在的可能性，研究了f（T）引力中的因果性问题。通过假设理想流体为物质源，我们发现流体的状态方程参数必须大于-1，才能使哥德尔解存在，而且临界半径rc是有限的，超过临界半径rc，因果关系被分解，它取决于物质和重力。值得注意的是，对于某些f（T）模型，允许哥德尔型解的完美流体甚至可以是正常物质，例如无压物质或辐射。然而，如果物质源是一个特殊的标量场，而不是一个完美的流体，那么rc → ∞和因果关系的破坏，从而避免。
The issue of causality in f(T) gravity is investigated by examining the possibility of existence of the closed timelike curves in the Godel-type metric. By assuming a perfect fluid as the matter source, we find that the fluid must have an equation of state parameter greater than minus one in order to allow the Godel solutions to exist, and furthermore the critical radius rc, beyond which the causality is broken down, is finite and it depends on both matter and gravity. Remarkably, for certain f(T) models, the perfect fluid that allows the Godel-type solutions can even be normal matter, such as pressureless matter or radiation. However, if the matter source is a special scalar field rather than a perfect fluid, then rc → ∞ and the causality violation is thus avoided.