Many problems in astrophysics involve a tremendous scale separation. A particularly dramatic example is the case of supermassive black holes, whose impact is felt on all of these scales. I’ll show how recent multi-physics and multi-scale simulations have transformed our understanding of how such black holes could form, “where they come from,” and how they influence galaxies. With the novel ability to follow the radiation-magneto-thermo-chemistry from scales of megaparsecs down to horizon scales, we are now seeing that much of the “conventional wisdom” in the field needs to be revised. Simulations are predicting qualitatively new types of accretion disks which in turn completely change our intuition about how black hole seeds grow rapid, how quasars shine and behave in mergers, how stars form around black holes, and how their feedback couples to the interstellar medium. I’ll also briefly review some of our group’s recent work connecting these disparate scales in the context of star formation, dust, and cosmic rays, involving novel ideas about stellar pollution, the origins of magnetic fields, and how cosmic rays influence galaxies.
