کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1894783 | 1533752 | 2014 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Cosmological singularities in Bakry-Ãmery spacetimes
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
ریاضیات
فیزیک ریاضی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Cosmological singularities in Bakry-Ãmery spacetimes Cosmological singularities in Bakry-Ãmery spacetimes](/preview/png/1894783.png)
چکیده انگلیسی
We consider spacetimes consisting of a manifold with Lorentzian metric and a weight function or scalar field. These spacetimes admit a Bakry-Ãmery-Ricci tensor which is a natural generalization of the Ricci tensor. We impose an energy condition on the Bakry-Ãmery-Ricci tensor and obtain singularity theorems of a cosmological type, both for zero and for positive cosmological constant. That is, we find conditions under which every timelike geodesic is incomplete. These conditions are given by “open” inequalities, so we examine the borderline (equality) cases and show that certain singularities are avoided in these cases only if the geometry is rigid; i.e., if it splits as a Lorentzian product or, for a positive cosmological constant, a warped product, and the weight function is constant along the time direction. Then the product case is future timelike geodesically complete while, in the warped product case, worldlines of certain conformally static observers are complete. Our results answer a question posed by J Case. We then apply our results to the cosmology of scalar-tensor gravitation theories. We focus on the Brans-Dicke family of theories in 4 spacetime dimensions, where we obtain “Jordan frame” singularity theorems for big bang singularities.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Geometry and Physics - Volume 86, December 2014, Pages 359-369
Journal: Journal of Geometry and Physics - Volume 86, December 2014, Pages 359-369
نویسندگان
Gregory J. Galloway, Eric Woolgar,