arXiv subjects

D. A. Grad

Publications and source records attributed to D. A. Grad.

3 recordsLinked to original sources

arXiv2018

Definitions of energy for the description of gravity as the splitting theory

We study the definitions of energy, naturally arising in the splitting theory, which is the field theoretic formulation of the Regge-Teitelboim gravity. The latter regards our spacetime as a surface embedded in a flat bulk. The splitting theory describes embedded spacetime in the language of the some field theory in a flat bulk. We consider the Noether energy-momentum tensor (EMT) and the metric EMT defined by the variation with respect to the metric of a flat bulk. We discuss a localizability of energy. Then using these EMTs we calculate the full energy of an isolated massive body. We compare the results with the standard general relativity results obtained from the Einstein energy-momentum pseudotensor (pEMT) and from the M{\o}ller pEMT. Finally, we propose the several ways of correction of the definitions of the energy in the splitting theory.

gr-qc↗

arXiv2017

Gravitational energy in the framework of embedding and splitting theories

We study various definitions of the gravitational field energy based on the usage of isometric embeddings in the Regge-Teitelboim approach. For the embedding theory we consider the coordinate translations on the surface as well as the coordinate translations in the flat bulk. In the latter case the independent definition of gravitational energy-momentum tensor appears as a Noether current corresponding to global inner symmetry. In the field-theoretic form of this approach (splitting theory) we consider Noether procedure and the alternative method of energy-momentum tensor defining by varying the action of the theory with respect to flat bulk metric. As a result we obtain energy definition in field-theoretic form of embedding theory which, among the other features, gives a nontrivial result for the solutions of embedding theory which are also solutions of Einstein equations. The question of energy localization is also discussed.

gr-qc↗

arXiv2014

Embeddings of the black holes in a flat space

We study the explicit embeddings of static black holes. We obtain two new minimal embeddings of the Schwarzchild-de Sitter metric which smoothly cover both horizons of this metric. The lines of time for these embeddings are more complicated than hyperbolas. Also we shortly discuss the possibility of using non-hyperbolic embeddings for calculation of the black hole Hawking temperature in the Deser and Levin approach.

gr-qc↗