Warm H2 as a probe of massive accretion and feedback through shocks and turbulence across cosmic time

We discuss the importance of the direct detection of molecular hydrogen (through redshifted mid-IR lines, and UV absorption) at high redshift as a probe of massive accretion and feedback processes in galaxies and protogalaxies and to potentially detect gas cooling and feeding the most massive and metal-free dark matter halos to z = 12.