Progress in cosmology has led to a much greater understanding of how galaxies, and clusters of galaxies, formed. But until recently there were major dicrepancies between observations and theoretical predictions.

It now seems that the missing link in the galaxy formation process has been identified – it is the energy liberated by the growth of massive black holes.

I will discuss the evidence pointing to a connection between black hole growth and galaxy formation, and describe recent progress in understanding how “cosmic feedback” works.