  An extraordinary recent development in astrophysics was the discovery of the
fossil relationship between central black hole mass and the stellar mass of
galactic bulges. The physical process underpinning this relationship has become
known as feedback. The Chandra X-ray Observatory was instrumental in realizing
the physical basis for feedback, by demonstrating a tight coupling between the
energy released by supermassive black holes and the gaseous structures
surrounding them. This white paper discusses how a great leap forward in X-ray
collecting area and spectral resolution will allow a qualitatively new way of
studying how feedback from black holes influenced the growth of structure.
