Towards solving the problem of star formation, from above

Stars are born in dense molecular clouds in the turbulent interstellar medium. 
The impact of the global state of the galaxy versus the local small scale 
environment on this process is not yet fully understood. I will discuss the 
processes that shape the density and velocity structure of the interstellar 
medium, focusing on gravity and stellar feedback, leading to observed scaling 
relations of molecular clouds and large scale HI properties. On galactic 
scales, star formation is known to be globally inefficient, whereas individual 
star forming clouds show a puzzling diversity with a spread of efficiencies 
on the order of 4 orders of magnitude. I will show how high resolution models 
of galaxies can shed light on this problem. Finally, I will present new 
results on the formation of the faintest galaxies in the Universe, Ultra 
Faint Dwarfs (UFDs), and how their extremely inefficient mode 
of star formation can be understood.