With the imminent launch of the James-Webb space telescope an unique window into the first billion years of the Universe will open.
The first billion years see galaxies growing at a rate that they will not maintain eve again during the history of the Universe, doubling in mass every few 100 million years. In addition, black holes grow to billions of solar masses from only thousands of solar masses. In my talk I will present results from numerical cosmological simulations trying to cover this epoch looking at the growth of galaxies and their black holes. I will discuss the physical drivers of this evolution and make the point that while thermo-hydrodynamical effects and feedback play a modulating role, the main driver remains gravity, and as such allows us to potentially probe it during those times. | 
