论文标题
一项有关莫里斯·托恩虫洞极端特性的最新研究调查
A survey of recent studies concerning the extreme properties of Morris-Thorne wormholes
论文作者
论文摘要
很长一段时间以来，莫里斯·托恩（Morris-Thorne）虫洞只能通过违反无效的能量条件来保持开放状态，而无效的能量状况可以以$τ-ρc^2> 0 $表达，其中$τ$是径向的张力。违反这种情况的问题通常称为“异国情调”。对于任何具有适度喉咙的虫洞，径向张力等于巨大的中子恒星的中心。将这一结果归因于异国问题似乎足够合理，但是它忽略了出于完全不同的原因引入外来物质的事实。此外，它的问题性质表明，外来物质的数量最少，但这将使高径向张力更难解释。如果数量无限小，则此解释将完全分解。通过调用$ f（r）$修饰的重力，实际上可以消除喉咙外来物质的需求，但是上述情况的否定，即$τ<ρc^2 $，表明我们不一定消除了高径向张力。该调查讨论了各种方法来说明高径向张力，在某些情况下是异国物质的可能起源。我们对可能的倍数连接宇宙进行了一些评论。
It has been known for a long time that Morris-Thorne wormholes can only be held open by violating the null energy condition, which can be expressed in the form $τ-ρc^2>0$, where $τ$ is the radial tension. Matter that violates this condition is usually referred to as "exotic." For any wormhole having a moderately-sized throat, the radial tension is equal to that at the center of a massive neutron star. Attributing this outcome to exotic matter seems reasonable enough, but it ignores the fact that exotic matter was introduced for a completely different reason. Moreover, its problematical nature suggests that the amount of exotic matter be held to a minimum, but this would make the high radial tension harder to explain. If the amount is infinitely small, this explanation breaks down entirely. By invoking $f(R)$ modified gravity, the need for exotic matter at the throat could actually be eliminated, but the negation of the above condition, i.e., $τ<ρc^2$, shows that we have not necessarily eliminated the high radial tension. This survey discusses various ways to account for the high radial tension and, in some cases, the possible origin of exotic matter. We conclude with some comments on a possible multiply-connected Universe.
