Pseudo-Riemannian geometry on a simplicial lattice and the extrinsic curvature tensor
We define the simplicial analogues of two concepts from differential topology: the concept of a point on the simplicial manifold and the concept of a tangent space on a simplicial manifold. We derive the simplicial analogues of parallel transport, the covariant derivative, connections, the Riemann curvature tensor, and the Einstein tensor. We construct the extrinsic curvature for a simplicial hypersurface using the simplicial covariant derivative. We discuss the importance of this simplicial extrinsic curvature to the 3+1 Regge-calculus program. It appears to us that the newly developed null-strut lattice is the most natural version of a 3+1 Regge lattice for the construction of extrinsic curvature. (A null-strut lattice is a 3+1 Regge spacetime lattice with TrK = const simplicial hypersurfaces, each connected to its two adjacent hypersurfaces entirely by simplicial light cones built of null struts.) Finally, we test the Regge-calculus version of the extrinsic curvature on a Bianchi type-IX simplicial hypersurface. The calculation agrees with the continuum expression to first order.
- Research Organization:
- Department of Mathematics, North Carolina State University, Raleigh, North Carolina 27695-8205
- OSTI ID:
- 6435935
- Journal Information:
- Phys. Rev. D; (United States), Journal Name: Phys. Rev. D; (United States) Vol. 39:4; ISSN PRVDA
- Country of Publication:
- United States
- Language:
- English
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