Normal galaxies are faint and complex X-ray sources that provide very powerful probes for fundamental astrophysical questions. Examples include: the study of populations of X-ray emitting sources; the study of the entire spectrum of black-hole phenomena; and galaxy formation and evolution in interaction with the surrounding environment. While exciting, all these fields { \bf require} Chandra sub-arcsecond resolution, and at least comparable spectral capabilities. They also require much large collecting areas. I argue that this is the direction we must plan for future X-ray observatories.
Categories: astro-ph