MG12 - Talk detail
 

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Abstract

Interacting Kerr-Newman fields

The interaction between two Kerr-Newman fields in the limit of zero gravitational constant is studied. A novel way of using the electromagnetic Lagrangian is employed to compute an interaction potential for the case of aligned spins. In this approach, the Kerr-Newman fields are considered as formally source-free, thereby obviating the need to insert sources by hand in the Lagrangian. The approach may be of relevance for subatomic applications. In particular, it is shown that the resulting interaction potential have a number of features in common with the nucleon-nucleon potential, both qualitatively and quantitatively.

A direct estimate of the spatial curvature of the universe

The main idea of this contribution is to calculate the average spatial curvature directly from the observed mass distribution of the universe. In short, our philosophy is that the curvature of the universe is generated solely by the matter it contains. Although this may seem as self-evident in the context of general relativity, the usual practice in cosmology is rather to use a top-down approach in which the curvature is calculated indirectly using a prescribed matter distribution as a source of the Einstein equations. By contrast, our approach may be seen as part of a bottom-up approach. In practical terms, we first calculate the far field spatial curvature generated by an isolated matter distribution which is in arbitrary motion. At this stage we obtain the result that the sign of the spatial curvature is necessarily positive. For the spatial curvature generated by multiple sources we show that it is sufficient to use linearized theory to compute the leading contributions. In the matter dominated era the spatial curvature is then seen to be generated by local sources at small redshifts. This fact makes it possible to calculate the total spatial curvature just by summing up the contributions from the observed discrete mass distribution. A crude estimate gives the value Omega_k ˜ -10^(-7) (k > 0).

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