Michael R. Moldover

Michael R. Moldover died on 8 August 2025.

Mike was born on 19 July 1940 in New York City, attended the Bronx High School of Science, and received degrees in physics from Rensselaer Polytechnic Institute (BS 1961) and Stanford University (MS 1962, PhD 1966). As a graduate student and later as an assistant professor at the University of Minnesota, Mike’s work focused on specific-heat measurements near the critical points of helium-3 and helium-4. In 1972, when he came to the National Bureau of Standards, now NIST, in Gaithersburg, Maryland, his work diversified to critical points in other systems, and he was lead author on an article in Reviews of Modern Physics that microgravity researchers called the “bible” on gravity effects near the critical point. With further NASA funding, Mike inspired and guided experiments that flew on the space shuttle in 1992, 1994, 1997, and 2003.

Further diversification included the experimental and theoretical development of resonators that could host acoustic and microwave resonances that led to two US patents. These tools have been used at NIST and elsewhere to measure properties of fluids, determine the thermodynamic temperature, and fix the value of the gas constant R. The most prominent measurement of R, done by Moldover et al. in 1988, inspired other such measurements internationally, culminating in the 2019 redefinition of the kelvin. In the final sentence of their 1988 paper, Mike and his coauthors made a personal commitment: "…we are willing to bet our own money at even odds that our reported value is correct to 5 parts in 10⁶, and if by any chance our value is shown to be in error by more than 10 parts in 10⁶, we are prepared to eat the apparatus, drink the mercury, and breathe the argon!” Happily, the value they reported in 1988 agrees with the final defined value within 1 part in 10⁶. Among his 200-plus publication titles, other examples of Mike’s diverse interests include “An interface phase transition complete to partial wetting” (1980), “Ab initio calculations for helium: a standard for transport property measurements” (1995), “Accurately measuring unsteady water flows using a dynamic standard” (2009), and “Design and capabilities of NIST’s scale-model smokestack simulator” (2015).

Mike’s most prominent awards were the Stratton Award for Research Excellence (NIST 1988), the Presidential Rank Award (US Office of Personnel Management 2009), the Touloukian Award (American Society of Mechanical Engineers 2012), and four medals awarded by the Department of Commerce (bronze 1980; silver 1982, 2011; gold 1987). Mike was a fellow of NIST, the Acoustical Society of America, and the American Physical Society.

Mike was a group leader at NIST for 20 years, first of the Fluid Science Group, which later merged with the Flow Group to become the Fluid Metrology Group, and he served one year as the acting chief of the Process Measurements Division. But the work that made him happiest was designing experiments, exploring data, and finding the best way to explain and present it to others. Mike continued to work after his retirement in 2019, publishing 11 articles and giving valuable advice and reviews to NIST colleagues.

Mike’s demeanor was conservative; he rarely complained, never gossiped, but had flashes of whimsey; his two cats were named Kelvin and Joule. Mike’s trustworthiness surely helped him grow and maintain his far-reaching network. Mike had about 140 coauthors, but his collaborations were usually in small groups. After excluding five committee articles, the average number of coauthors was only 3.1.

Mike emphasized that the context for every scientist’s work is people and not publications: In your literature research, identify the driving author and pick up that telephone. In your own work, write well, add a table that makes your results accessible to the theorists, and ask yourself if those results could compel someone to change what they are doing. In your institution, be loyal but always do the right thing. Encourage social connection by eating lunch together daily and drinking beer together on Friday afternoon.

At NIST, Mike directly influenced, either as an adviser or a collaborator, a dozen postdocs and a dozen more guest researchers. Most have gone on to various positions at NIST or at universities and metrology institutes worldwide. He was loyal to his colleagues and dedicated to making NIST the best metrology institute possible.

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