Large, deep sky surveys from galaxy mapping and CMB experiments can not only probe the cosmological parameters but the framework of the dark sector and the early universe. I discuss how galaxy spatial clustering can probe a free form inflationary power spectrum and strong lensing time delays can yield the Hubble constant. CMB results probe cosmic history over a factor 100,000 in expansion and test whether there are extra relativistic species or early dark energy, while at later times CMB lensing measures neutrino mass. For galaxy redshift surveys such as DESI or PFS I show how high performance simulations allow us to model redshift space distortions at the percent level into the nonlinear regime, mapping the growth history of structure and testing gravity.