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Volume 15: Pages 176-182, 2002

Is the Gravitational Energy Density Observable?

Jean Chevalier

Association F. Gonseth/Institut de la méthode, St‐Imier, Switzerland

Although the tetrad formalism of general relativity allows us to localize the gravitational energy, it doesn't furnish any way to measure it. In electrodynamics the existence of two kinds of charges is strongly connected with the possibility of measuring the field energy density. Since there are no negative masses, it is very unlikely that the gravitational energy will be directly observable some day. But nothing prevents us from imagining an indirect method. In the tetrad formalism the gravitational force is expressed by a (“true”) tensor that is closely related to the gravitational energy‐momentum‐stress tensor. In the case of a sphere consisting of a perfect incompressible fluid we show that measuring this force allows us to verify the formula that gives the gravitational energy density. Therefore, we may consider this procedure as an indirect way to measure the latter.

Keywords: tetrad formalism, localization of the gravitational energy, measurement of the gravitational force

Received: February 15, 2001; Published online: December 15, 2008