What were the first objects that formed in the Universe? Prof. Abel's group explores the first billion years of cosmic history using ab initio supercomputer calculations. He has shown from first principles that the very first luminous objects are very massive stars and has developed novel numerical algorithms using adaptive-mesh-refinement simulations that capture over 14 orders of magnitude in length and time scales. He currently continues his work on the first stars and first galaxies and their role in chemical enrichment and cosmological reionization. His group studies any of the first objects to form in the universe: first stars, first supernovae, first HII regions, first magnetic fields, first heavy elements, and so on. Most recently he is pioneering novel numerical algorithms to study collisionless fluids such as dark matter which makes up most of the mass in the Universe as well as astrophysical and terrestrial plasmas. He was the director of the Kavli Institute for Particle Astrophysics and Cosmology and Division Director at SLAC 2013-2018.