Relativistic corrections in cosmological modelling
The next generation of telescopes will usher in an era of precision cosmology, capable of determining the cosmological model to beyond the percent level. For this to be effective, the theoretical model must be understood to at least the same level of precision. A range of subtle relativistic effects remain to be explored theoretically, and offer the potential for probing general relativity in this new regime. These range from dynamical effects such as frame dragging, to modifications to gravitational lensing, to more speculative modifications to the background dynamics from averaging over structure. These can affect the concordance model at the percent level or possibly more, meaning precision cosmology must also now be considered relativistic.