# Cosmological Gravity

A key assumption, at the heart of cosmological analysis, is that

gravity is accurately described by Einstein’s General Theory of

Relativity. While Einstein’s theory of gravity has stood the test of

time, as yet, the only precise tests of General Relativity are on much

smaller scales (of order 1 Astronomical Unit). Assuming they are

correct on cosmological scales involves an extrapolation of around 15

orders of magnitude.

At Oxford we are working on tests and constraints which could probe

the nature of gravity on the largest observable scales. In doing so

it should be possible to determine whether General Relativity or some

extension of it, is truly an accurate description of gravity in a

cosmological setting.

We are working on a three main topics to understand cosmological

gravity:

- we are building a formal framework that can unify gravitational

theories with a goal of coming up with a systematic classification;

- we are developing accurate tools for calculating observational

predictions on linear and non-linear scales;

- we are devising specific analysis methods and tools for current and

future cosmological observations.