Timothy Guy (Tim) Trucano

Timothy Guy Trucano (Tim), a wise mentor, cherished friend, dedicated former husband, brilliant mathematician and computational physicist at Sandia National Laboratories, passed away after a brief illness on September 20, 2026. He was 75 years old.

Tim spent a decorated 38-year career at Sandia, gaining widespread recognition for his expertise in computational physics and, later, for articulating the Verification and Validation (V&V) frameworks used in the Department of Energy's Advanced Simulation and Computing (ASC) initiative, key computational technologies used to certify the ongoing safety, reliability and security of the US nuclear deterrent.

Tim was born in Dayton, Ohio, on May 8, 1951, to Guy and Lucille Trucano. He spent his childhood in Ohio and Arizona before moving to Albuquerque, New Mexico as a young teen, graduating from Del Norte High School 1969. Tim completed his Bachelor of Science (1973), Master's (1976), and Doctor of Philosophy (1980) degrees in Mathematics at the University of New Mexico, writing a dissertation focused on the application of functional analysis and operator theory to quantum mechanical scattering. It was a topic that fascinated him for the rest of his life. He received all degrees with honors and was a member of Phi Beta Kappa.

Upon completing his doctorate, Tim joined Sandia in 1980 as a Member of Technical Staff in the Shock Physics department. As an undergraduate, Tim had spent summers in both the Shock Physics and Explosive Physics divisions at Sandia, thoroughly enjoying the opportunity to work at the intersection of mathematics and physics. He later said that being hired into Sandia was the luckiest thing that had ever happened to him.

Over the course of his career in the Department of Energy (DOE) and the DOE National Nuclear Security Administration (NNSA), Tim devoted himself to impactful work in national security. In the 1980s, Tim worked on a range of computational physics applications, including shock hydrodynamics, equation of state and constitutive modeling, and high energy density physics. By the early 1990s, he had emerged as the lead analyst running urgent critical national security simulations on the earliest massively parallel computers. The computational codes were new, the computers difficult to use, and the physics models under development. In this environment, Tim was something of a computational skeptic, never taking code correctness for granted. On a near-daily basis, he walked into his colleagues' offices (including that of a future Sandia National Laboratories director, Dr. James Peery) to point out issues with their codes, an irritating but ultimately beneficial habit that strengthened everyone around him.

Tim's experience in experimental shock wave physics, and his passionate advocacy for rigorous evidence of computational correctness, seeded the next phase of his career. In 1997, Tim organized and held the first Tri-Lab (Sandia, Los Alamos and Lawrence Livermore) Verification and Validation Workshop, launching what would become a permanent element of the entire ASC program.

Over the next twenty years, in collaboration with Sandia's Martin Pilch and William Oberkampf, Tim defined and articulated the structure, philosophy, and execution of a rigorous program in code verification, validation and uncertainty quantification (V&V/UQ). This was something of an uphill battle: as Tim frequently observed, "V&V takes all the fun out of computational science!" Nevertheless, Trucano, Pilch and Oberkampf doggedly insisted on the importance of quality control in predictive modeling and simulation. Together, they established the foundation for today's V&V/UQ program, not just at Sandia but across the NNSA.

Throughout his career, Tim was widely admired for his ability to explain complex mathematical and physics problems in elegant, accessible English. A talented writer and excellent speaker, Tim authored hundreds of presentations, reports and articles that continue to be cited within and outside the national laboratories.

As both an individual and a team contributor, Tim's work won recognition both within and outside Sandia. He was named a Distinguished Member of Technical Staff in 1995 and Senior Scientist in 2005. He won accolades from the United States Navy, Army and the Air Force; the DOE and the NNSA, and the R&D 100 Awards; in addition to dozens of internal nominations and awards from appreciative Sandia colleagues and leaders. Even after his retirement in 2018, Tim continued to support the expansion of V&V/UQ practices outside the nuclear weapons programs. Most recently, he had been contributing to Sandia discussions about determining the extent to which artificial intelligence applications are "fit for purpose."

Given Tim's tremendous impact, it is simply astonishing to think that he received a D in mathematics as an eighth grader and failed math in the ninth grade. As he told the Sandia Lab News in 2017, "I was a relatively poor student who scored well in verbal on standardized tests and was told consistently that I wasn't any good at math." His trajectory changed when he transferred to Del Norte High School in Albuquerque, where he picked up a biography of mathematician Norbert Wiener, which he found inspiring. With the support of excellent teachers and a new friend group that valued academics, Tim excelled in school, graduating in 1969 with his heart set on a career in mathematics.

Ever aware of the support he had received from others throughout his education and his career, Tim was unfailingly generous with his knowledge. Newly hired and early career staff were welcome in his office, no matter their educational background or area of expertise. Tim would set aside his own considerable work to listen to their challenges, provide judicious input, and serve as mentor, advisor and friend. Perhaps because he saw himself as an underdog, Tim paid careful attention to the challenges women face in the national laboratory workplace. This made him an invaluable career guide and advocate for recognition of their accomplishments. It would be difficult to fully track the breadth and depth of Tim's wise impact on R&D careers over the nearly 40 years he worked at Sandia.

Tim had wide-ranging interests beyond math and physics. As a younger adult, he enjoyed rock climbing and cycling. He loved sports and was a lifelong fan of The Ohio State, spending his fall Saturdays kvetching about refereeing while paging through technical articles during commercial breaks. Tim was obsessed with excellent coffee and kept espresso beans, grinders, cups and machines at his home and his office. He loved music, television shows, movies, and books of all kinds, maintaining an eclectic media collection that quite literally covered most of the walls in his house. And no matter where he went, Tim was never without something to read. After his retirement, Tim met regularly with friends and colleagues for breakfast. His favorite spot was The Grove, where he would invariably arrive early to enjoy a latte and read a bit before his friend(s) showed up.

In 1991, Tim married Megan Florence, a fellow mathematician who taught at the Albuquerque Technical Vocational Institute (now Central New Mexico Community College). Despite their divorce in 1997, Tim remained close to Megan until his death. Tim had deep affection for all animals, but was particularly fond of dogs, whose behavior and cognition he found endlessly fascinating. Together, Megan and Tim rescued, rehabilitated and cared for multiple dogs both during and after their marriage, and Tim gave generously to many companion animal rescues throughout his life.

Tim had an amazing intellect, coupled with graciousness, humility, and quick wit. He will be remembered for his many sharp observations: "In the absence of evidence, anything is possible!" If a life's significance is marked by the hole left behind when the individual is gone, then Tim's life was deeply significant and the absence painful. He will be missed.

He is survived by his former spouse, Megan Florence; his niece, Hanna Florence-Livoti; nephew, Keegan Florence-Livoti; and countless friends and colleagues.

A Memorial Service for Tim will be held Saturday, October 24th, 2026, 11:00 a.m., at FRENCH - University, with a reception to follow. The favor of an RSVP is requested to trucanomemorial@gmail.com to manage refreshments.

In lieu of flowers, please make donations in Timothy Trucano's name to Kindred Spirits Animal Sanctuary, kindredspiritsnm.org.