Kerr-Schild-Kundt metrics are universal

Sisman, Tahsin Cagri
Tekin, Bayram
We define (non-Einsteinian) universal metrics as the metrics that solve the source-free covariant field equations of generic gravity theories. Here, extending the rather scarce family of universal metrics known in the literature, we show that the Kerr-Schild-Kundt class of metrics are universal. Besides being interesting on their own, these metrics can provide consistent backgrounds for quantum field theory at extremely high energies.


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In a nonlinear theory, such as general relativity, linearized field equations around an exact solution are necessary but not sufficient conditions for linearized solutions. Therefore, the linearized field equations can have some solutions which do not come from the linearization of possible exact solutions. This fact can make the perturbation theory ill defined, which would be a problem both at the classical and semiclassical quantization level. Here we study the first and second order perturbation theory i...
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Citation Formats
M. GÜRSES, T. C. Sisman, and B. Tekin, “Kerr-Schild-Kundt metrics are universal,” CLASSICAL AND QUANTUM GRAVITY, pp. 0–0, 2017, Accessed: 00, 2020. [Online]. Available: