Mary Ann Ruth (Mansigh) Karlsen

Mary Ann Ruth (Mansigh) Karlsen died Aug. 28, 2024. She was 91.

Mary Ann Ruth (Mansigh) Karlsen was born Sept. 12, 1932, in rural Otter Tail County, Minnesota. She was raised by her parents, Esther and John. She was the valedictorian when she graduated from New York Mills High School and went on to the University of Minnesota at Duluth on a scholarship, graduating with a bachelor of science with a double major in math and chemistry. She was hired at Lawrence Radiation Laboratory (later renamed Lawrence Livermore National Laboratory) in 1955 and worked there as computer scientist for 40 years. Her first assignment was with Berni Alder, using computer simulations to model the behavior of materials at the atomic level. They developed the field of molecular dynamics, which is now studied in departments around the world and has revolutionized scientific understanding of the behavior of matter. She was Alder’s entire software development team and was recognized as such in the seminal research papers that established the field. She programmed many mainframe computers, from the UNIVAC to the CRAY supercomputers, quickly recoding her programs for each new machine so she could use all the unused computer time before the other programmers learned the machine. For the remainder of her career, she developed code for another eminent scientist, Don Wuebbles. This work was modeling the atmosphere for ozone depletion potentials aimed at the protection of the ozone layer. When Wuebbles left LLNL in 1994, she retired.

Broader recognition of Mary Ann’s contributions to the field of computational physics began around 2015, when she attended Bernie’s 90th birthday symposium at the Lab, and the Women in Science and Engineering group of the LLLWA invited Mary Ann to speak at a brown bag.  She has subsequently been recognized with multiple invitations to speak, including from the Ecole Polytechnique Fédérale de Lausanne (EPFL) in November 2017, where she was highly regarded and given the royal treatment. Soon after, EPFL began a lecture series named after her. On March 9, 2018, she was the keynote speaker for Marvell Semiconductor's International Women’s Day celebration. Most recently, on Aug. 25, 2024, she was delighted to receive news that she was selected for an honorary doctorate from Eidgenössische Technische Hochschule Zürich (Federal Institute of Technology Zurich).

Mary Ann is survived by her spouse, Cori Elena Karlsen, as well as her nieces and nephews.  

A Celebration of Life will be held Oct. 11, at Callaghan Mortuary, 3833 East Ave., Livermore, at 11:00 a.m. and will be followed by a light lunch. In lieu of flowers, please make a donation to Asante Africa at 1334 Carlton Place, Livermore.