A new proof of Birkhoff ’ s theorem ∗ Hans
نویسنده
چکیده
Assuming SO(3)-spherical symmetry, the 4–dimensional Einstein equation reduces to an equation conformally related to the field equation for 2–dimensional gravity following from the Lagrangian L = |R|1/3. Solutions for 2–dimensional gravity always possess a local isometry because the traceless part of its Ricci tensor identically vanishes. Combining both facts, we get a new proof of Birkhoff’s theorem; contrary to other proofs, no coordinates must be introduced. The SO(m)-spherically symmetric solutions of the (m+1)–dimensional Einstein equation can be found by considering L = |R|1/m in two dimensions. This yields several generalizations of Birkhoff’s theorem in an arbitrary number of dimensions, and to an arbitrary signature of the metric. to appear in Grav. and Cosmol. ∗extended version of a lecture read at the university of Cagliari/Italy April 22, 1997
منابع مشابه
A new proof for the Banach-Zarecki theorem: A light on integrability and continuity
To demonstrate more visibly the close relation between thecontinuity and integrability, a new proof for the Banach-Zareckitheorem is presented on the basis of the Radon-Nikodym theoremwhich emphasizes on measure-type properties of the Lebesgueintegral. The Banach-Zarecki theorem says that a real-valuedfunction $F$ is absolutely continuous on a finite closed intervalif and only if it is continuo...
متن کاملA Short Proof of the Birkhoff-von Neumann Theorem
The Birkhoff-von Neumann Theorem has been proved many times in the literature with a number of different methods, some inductive, some constructive, some existential. We offer a new proof that is a little more direct than most, though nonconstructive.
متن کاملCommon xed point theorem for w-distance with new integral type contraction
Boujari [5] proved a fixed point theorem with an old version of the integraltype contraction , his proof is incorrect. In this paper, a new generalizationof integral type contraction is introduced. Moreover, a fixed point theorem isobtained.
متن کاملBirkhoff's Theorem from a geometric perspective: A simple example
From Hilbert's theorem of zeroes, and from Noether's ideal theory, Birkhoff derived certain algebraic concepts (as explained by Tholen) that have a dual significance in general toposes, similar to their role in the original examples of algebraic geometry. I will describe a simple example that illustrates some of the aspects of this relationship. The dualization from algebra to geometr...
متن کاملAnother proof of Banaschewski's surjection theorem
We present a new proof of Banaschewski's theorem stating that the completion lift of a uniform surjection is a surjection. The new procedure allows to extend the fact (and, similarly, the related theorem on closed uniform sublocales of complete uniform frames) to quasi-uniformities ("not necessarily symmetric uniformities"). Further, we show how a (regular) Cauchy point on a closed uniform subl...
متن کامل