# nLab universal spacetime

Contents

### Context

#### Gravity

gravity, supergravity

# Contents

## Idea

Universal spacetimes are spacetimes for which all conserved symmetric rank-2 tensors, constructed as contractions of polynomials from the metric, the Riemann tensor and its covariant derivatives of arbitrary order, are multiples of the metric. Consequently, metrics of universal spacetimes solve vacuum equations of motion of all gravitational theories, i.e. extremize the Einstein-Hilbert action with given cosmological constant and arbitrary higher curvature correction. In the literature, universal metrics are also discussed as metrics with vanishing quantum corrections and as classical solutions to string theory. Widely known examples of universal metrics are certain Ricci flat pp-wave spacetimes.

## References

The first examples are due to

The terminology was introduced in

Classification results are discussed in

Last revised on January 9, 2019 at 01:05:45. See the history of this page for a list of all contributions to it.