Cosmology seminar: Measuring the distortion of time with large-scale structure

To test the theory of gravity one needs to test, on one hand, how space and time are distorted by matter and, on the other hand, how matter moves in a distorted space-time. Current observations provide tight constraints on the motion of matter, through the so-called redshift-space distortions, but they only provide a measurement of the sum of the spatial and temporal distortions, via gravitational lensing. In this talk I will present a novel method to measure the time distortion on its own, and I will show that it will be detectable by future surveys like the SKA. I will then discuss new tests of gravity that can be build from this measurement.