scholarly journals A Kastler–Kalau–Walze type theorem for five-dimensional manifolds with boundary

2015 ◽  
Vol 12 (05) ◽  
pp. 1550064 ◽  
Author(s):  
Jian Wang ◽  
Yong Wang
Keyword(s):  
General Relativity ◽  
Dirac Operator ◽  
Type Theorem ◽  
Manifolds With Boundary ◽  
Wodzicki Residue ◽  
Hilbert Action

The Kastler–Kalau–Walze theorem, announced by A. Connes, shows that the Wodzicki residue of the inverse square of the Dirac operator is proportional to the Einstein–Hilbert action of general relativity. In this paper, we prove a Kastler–Kalau–Walze type theorem for five-dimensional manifolds with boundary.

scholarly journals An Obata-type theorem on compact Einstein manifolds with boundary

2021 ◽  
Author(s):  
Kazuo Akutagawa
Keyword(s):  
Boundary Condition ◽  
Smooth Boundary ◽  
Type Theorem ◽  
Type Inequality ◽  
Einstein Metric ◽  
Manifolds With Boundary ◽  
Einstein Manifolds ◽  
Conformal Class ◽  
Totally Geodesic ◽  
Yamabe Constant

AbstractWe show a kind of Obata-type theorem on a compact Einstein n-manifold $$(W, \bar{g})$$ ( W , g ¯ ) with smooth boundary $$\partial W$$ ∂ W . Assume that the boundary $$\partial W$$ ∂ W is minimal in $$(W, \bar{g})$$ ( W , g ¯ ) . If $$(\partial W, \bar{g}|_{\partial W})$$ ( ∂ W , g ¯ | ∂ W ) is not conformally diffeomorphic to $$(S^{n-1}, g_S)$$ ( S n - 1 , g S ) , then for any Einstein metric $$\check{g} \in [\bar{g}]$$ g ˇ ∈ [ g ¯ ] with the minimal boundary condition, we have that, up to rescaling, $$\check{g} = \bar{g}$$ g ˇ = g ¯ . Here, $$g_S$$ g S and $$[\bar{g}]$$ [ g ¯ ] denote respectively the standard round metric on the $$(n-1)$$ ( n - 1 ) -sphere $$S^{n-1}$$ S n - 1 and the conformal class of $$\bar{g}$$ g ¯ . Moreover, if we assume that $$\partial W \subset (W, \bar{g})$$ ∂ W ⊂ ( W , g ¯ ) is totally geodesic, we also show a Gursky-Han type inequality for the relative Yamabe constant of $$(W, \partial W, [\bar{g}])$$ ( W , ∂ W , [ g ¯ ] ) .

The Einstein field equations

2019 ◽  
pp. 52-58
Author(s):  
Steven Carlip
Keyword(s):  
General Relativity ◽  
Conservation Laws ◽  
Newtonian Gravity ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Noether’S Theorem ◽  
Geodesic Deviation ◽  
Fundamental Equations ◽  
Hilbert Action ◽  
Qualitative Discussion

The Einstein field equations are the fundamental equations of general relativity. After a brief qualitative discussion of geodesic deviation and Newtonian gravity, this chapter derives the field equations from the Einstein-Hilbert action. The chapter contains a derivation of Noether’s theorem and the consequent conservation laws, and a brief discussion of generalizations of the Einstein-Hilbert action.

scholarly journals Investigating $f(R)$ gravity and cosmologies

2021 ◽  
Author(s):  
Vaibhav Kalvakota
Keyword(s):  
General Relativity ◽  
Lagrangian Density ◽  
Ricci Scalar ◽  
Metric Tensor ◽  
Extended Theory ◽  
Theories Of Gravity ◽  
Theory Of Gravity ◽  
Hilbert Action ◽  
Geometric Nature

The f (R) theory of gravity is an extended theory of gravity that is based on general relativity in the simplest case of $f(R) = R$. This theory extends such a function of the Ricci scalar into arbitrary functions that are not necessarily linear, i.e. could be of the form $f(R) = \alpha R^{2}$. The action for such a theory would be $S_{EH} = \frac{1}{2k} \int f(R) + L^{m}\; d^{4}x\sqrt{−g}$, where $S_{EH}$ is the Einstein-Hilbert action for our theory, $g$ is the determinant of the metric tensor $g_{\mu \nu}$ and $L^{m}$ is the Lagrangian density for matter. In this paper, we will look at some of the physical implications of such a theory, and the importance of such a theory in cosmology and in understanding the geometric nature of such f (R) theories of gravity.

Riemannian manifolds

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
General Relativity ◽  
Curvature Tensor ◽  
Riemannian Manifolds ◽  
Covariant Derivative ◽  
Einstein Equations ◽  
Civita Connection ◽  
Levi Civita Connection ◽  
Hilbert Action

This chapter is about Riemannian manifolds. It first discusses the metric manifold and the Levi-Civita connection, determining if the metric is Riemannian or Lorentzian. Next, the chapter turns to the properties of the curvature tensor. It states without proof the intrinsic versions of the properties of the Riemann–Christoffel tensor of a covariant derivative already given in Chapter 2. This chapter then performs the same derivation as in Chapter 4 by obtaining the Einstein equations of general relativity by varying the Hilbert action. However, this will be done in the intrinsic manner, using the tools developed in the present and the preceding chapters.

A general Kastler–Kalau–Walze type theorem for manifolds with boundary

2016 ◽  
Vol 13 (01) ◽  
pp. 1650003 ◽  
Author(s):  
Jian Wang ◽  
Yong Wang
Keyword(s):  
General Expression ◽  
Type Theorem ◽  
Manifolds With Boundary ◽  
Theor Phys ◽  
Geometric Data ◽  
Lower Dimensional

In this paper, we establish a general Kastler–Kalau–Walze type theorem for any dimensional manifolds with boundary which generalizes the results in [Y. Wang, Lower-dimensional volumes and Kastler–Kalau–Walze type theorem for manifolds with boundary, Commun. Theor. Phys. 54 (2010) 38–42]. This solves a problem of the referee of [J. Wang and Y. Wang, A Kastler–Kalau–Walze type theorem for five-dimensional manifolds with boundary, Int. J. Geom. Meth. Mod. Phys. 12(5) (2015), Article ID: 1550064, 34 pp.], which is a general expression of the lower dimensional volumes in terms of the geometric data on the manifold.

Eigenvalues of the Dirac Operator on Manifolds¶with Boundary

2001 ◽  
Vol 221 (2) ◽  
pp. 255-265 ◽  
Author(s):  
Oussama Hijazi ◽  
Sebastián Montiel ◽  
Xiao Zhang
Keyword(s):  
Dirac Operator ◽  
Manifolds With Boundary

GEOMETRIC DUALITY AND CHERN–SIMONS MODIFIED GRAVITY

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1323-1327 ◽  
Author(s):  
L. A. CABRAL
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Modified Gravity ◽  
Kerr Metric ◽  
Nontrivial Solutions ◽  
Topological Current ◽  
Chern Simons ◽  
Hilbert Action ◽  
Black Hole Solutions ◽  
Geometric Duality

We consider a theory which involves an extension of general relativity known as Chern–Simons modified gravity (CSMG). In this theory the standard Einstein–Hilbert action is extended with a gravitational Pontryagin density that is obtained from a divergence of a Chern–Simons topological current. The extended theory has the standard Schwarzchild metric as solution, however, only a perturbed Kerr metric holds solution. From the exact Kerr metric we construct dual metrics to search for rotating black hole solutions. The conditions on the Killing tensors associated with dual metrics entail nontrivial solutions to CSMG.

scholarly journals A Kastler-Kalau-Walze Type Theorem and the Spectral Action for Perturbations of Dirac Operators on Manifolds with Boundary

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Yong Wang
Keyword(s):  
Type Theorem ◽  
Dirac Operators ◽  
Compact Manifolds ◽  
Manifolds With Boundary ◽  
Spectral Action ◽  
Gravitational Action

We prove a Kastler-Kalau-Walze type theorem for perturbations of Dirac operators on compact manifolds with or without boundary. As a corollary, we give two kinds of operator-theoretic explanations of the gravitational action on boundary. We also compute the spectral action for Dirac operators with two-form perturbations on 4-dimensional compact manifolds.

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