Unimodular relativity and cosmological constant
Unimodular relativity and cosmological constant
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幺模相对论和宇宙常数
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
James E. Baugh
中科院分区：
文献类型：
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作者：
D. Finkelstein;Andrei Galiautdinov;James E. Baugh
单模相对论是一种关于引力和时空的理论，它有一个固定的绝对时空体积元，即模，我们假设它与该体积元中微观模块的数量成正比。在广义相对论中，一个任意的固定测度可以作为规范条件，而在幺模相对论中，它是由体积中的事件决定的。由于这似乎打破了一般的协变，一些人认为它允许物质应力-能量张量的非零协变发散和可变的宇宙学“常数”。然而，在拉格朗日幺模相对论中，即使动力学中有引力场的高阶导数，通常的协变连续性仍然成立，宇宙学常数仍然是引力场方程的积分常数。
Unimodular relativity is a theory of gravity and space–time with a fixed absolute space–time volume element, the modulus, which we suppose is proportional to the number of microscopic modules in that volume element. In general relativity an arbitrary fixed measure can be imposed as a gauge condition, while in unimodular relativity it is determined by the events in the volume. Since this seems to break general covariance, some have suggested that it permits a nonzero covariant divergence of the material stress-energy tensor and a variable cosmological “constant.” In Lagrangian unimodular relativity, however, even with higher derivatives of the gravitational field in the dynamics, the usual covariant continuity holds and the cosmological constant is still a constant of integration of the gravitational field equations.