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arXiv 1208.5237gr-qc
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Birkhoff定理的四部曲

The tetralogy of Birkhoff theorems

Hans-Jürgen Schmidt

摘要:

我们把已有的Birkhoff型定理分为四类:第一类是在场论中,该定理指出引力场不存在螺旋度0-和自旋0-部分;第二,在相对论天体物理学中,它是这样的陈述,即球对称恒星的引力远场除了质量外,不携带任何关于恒星的信息;因此,径向振荡的恒星具有静态的引力远场。第三,在数学物理中,伯克霍夫定理是这样的:在零测度的奇异例外情况下,爱因斯坦真空场方程的球对称解(λ = 0)可以用史瓦西度规表示;当λ不等于0时,它是史瓦西-德西特度规。第四,在微分几何中,任何类型的陈述:伪黎曼时空家族的每个成员都有比原来的度量分析所期望的更多的等距,都被称为伯克霍夫型定理。在第四个这些类,我们提出了一些新的结果与进一步的价值观的维度和签名的相关空间,包括他们是一些反例:家庭的时空没有伯克霍夫型定理是有效的。这些反例进一步证实了猜想,即伯克霍夫型定理起源于二维伪黎曼空间的里奇张量的两个特征值总是重合的性质,这一性质在高维空间中没有类似之处。因此,伯克霍夫型定理只存在于那些可简化为二维的物理情形中。

英文摘要:

We classify the existent Birkhoff-type theorems into four classes: First, in field theory, the theorem states the absence of helicity 0- and spin 0-parts of the gravitational field. Second, in relativistic astrophysics, it is the statement that the gravitational far-field of a spherically symmetric star carries, apart from its mass, no information about the star; therefore, a radially oscillating star has a static gravitational far-field. Third, in mathematical physics, Birkhoff's theorem reads: up to singular exceptions of measure zero, the spherically symmetric solutions of Einstein's vacuum field equation with Lambda = 0 can be expressed by the Schwarzschild metric; for Lambda unequal 0, it is the Schwarzschild-de Sitter metric instead. Fourth, in differential geometry, any statement of the type: every member of a family of pseudo-Riemannian space-times has more isometries than expected from the original metric ansatz, carries the name Birkhoff-type theorem. Within the fourth of these classes we present some new results with further values of dimension and signature of the related spaces; including them are some counterexamples: families of space-times where no Birkhoff-type theorem is valid. These counterexamples further confirm the conjecture, that the Birkhoff-type theorems have their origin in the property, that the two eigenvalues of the Ricci tensor of two-dimensional pseudo-Riemannian spaces always coincide, a property not having an analogy in higher dimensions. Hence, Birkhoff-type theorems exist only for those physical situations which are reducible to two dimensions.

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