Frans Pretorius (born 31 July 1973 in Johannesburg) is a South African and Canadian physicist, specializing in computer simulations in astrophysics and numerical solutions of Einstein's field equations. He is professor of physics at Princeton University and director of the Princeton Gravity Initiative.
At the University of Victoria, Pretorius studied computer engineering with bachelor's degree in 1996 and then studied physics with master's degree in 1999 with master's thesis Topics in Black Hole Physics under the supervision of Werner Israel. Pretorius received his Ph.D. in 2002 from the University of British Columbia under the supervision of Matthew Choptuik. For his doctoral dissertation on numerical simulation of gravitational collapse, Pretorius received the 2003 Nicholas Metropolis Award of the American Physical Society (APS). As a postdoc, he was from 2002 to 2005 the Richard Chase Tolman Fellow at Caltech. He became an assistant professor in 2005 at the University of Alberta and in 2007 at Princeton University.
His research deals with numerical simulations in general relativity theory, especially gravitational collapse, collision, and mergers of black holes and consequent emission of gravitational waves. He has developed new methods of adaptive meshes, which are used in adaptive mesh refinement for coupled elliptic-hyperbolic systems.
Pretorius has numerically investigated the possibilities and the signatures of small black holes in particle colliders such as the LHC. Small black holes might be formed with very high collision energies,  the energy required might be a factor 2.3 smaller than previously assumed, but such high energies are extremely far from the capabilities of the LHC. With Abhay Ashtekar and Fethi Ramazanoğlu, he investigated the evaporation of 2D black holes. Pretorius and his collaborators numerically investigated the high energy collision of two black holes.
Pretorius was a Sloan Fellow in 2010 and received in 2010 the Aneesur Rahman Prize for Computational Physics. In 2011 he was elected a Fellow of the American Physical Society. In 2017 he was awarded the New Horizons in Physics Prize for the development of the first computer code that can simulate the spiral movement and the fusion of two black holes; in 2017 five other physicists in two different groups shared the prize for work done independently of Pretorius.
- Metropolis Award
- Pretorius, Choptuik Adaptive Mesh Refinement for Coupled Elliptic-Hyperbolic Systems, J. Comput. Phys., 218, 2006, 246-274, Arxiv
- William E. East, Frans Pretorius Ultrarelativistic Black Hole Formation, Phys. Rev. Lett. 110, 2013, 101101, doi:10.1103/PhysRevLett.110.101101; APS synopsis
- Choptuik, Pretorius Ultra Relativistic Particle Collisions, Phys. Rev. Lett., 104, 2010, 111101
- Ashtekar, Pretorius, Ramazanoğlu Surprises in the evaporation of 2D black holes, Phys.Rev. Lett., 106, 2011, 106.161303 doi:10.1103/PhysRevLett.106.161303
- U. Sperhake, V. Cardoso, F. Pretorius, E. Berti, J. A. Gonzalez The high energy collision of two black holes, Phys. Rev. Lett. 101, 2008, 161101, arxiv
- Gaal, Rachel (12 December 2016). "APS Fellows Awarded Breakthrough Prizes in Silicon Valley". APS News, aps.org.