Nicholas Metropolis

Nicholas Constantine Metropolis (Greek: Νικόλαος Μητρόπουλος; June 11, 1915 – October 17, 1999) was a Greek-American physicist.

Metropolis received his BSc (1937) and PhD in physics (1941, with Robert Mulliken) at the University of Chicago. Shortly afterwards, Robert Oppenheimer recruited him from Chicago, where he was collaborating with Enrico Fermi and Edward Teller on the first nuclear reactors, to the Los Alamos National Laboratory.

He arrived in Los Alamos in April 1943, as a member of the original staff of fifty scientists. He came back to Los Alamos in 1948 to lead the group in the Theoretical Division that designed and built the MANIAC I computer in 1952 that was modeled on the IAS machine, and the MANIAC II in 1957.

Nicolas Metropolis was born on June 11, 1915, in Chicago, US. Metropolis received his BSc (1936) and PhD in chemical physics (1941) at the University of Chicago. During his PhD he worked with Robert Mulliken. After graduation, he worked as an instructor at the University of Chicago with James Franck. Shortly afterwards, in 1943, Robert Oppenheimer recruited him from Chicago for the Manhattan Project, where he worked in Harold C. Urey's group. Later he joined University of Chicago Metallurgical Laboratory and worked under Edward Teller's supervision, who encouraged him to move into theoretical physics. At Los Alamos Metropolis worked together with Richard Feynman on "electromechanical devices used for hand computations".

After World War II, he returned to the faculty of the University of Chicago as an assistant professor. He came back to Los Alamos in 1948 to lead the group in the theoretical division that designed and built the MANIAC I computer in 1952 that was modeled on the IAS machine, and the MANIAC II in 1957. (John von Neumann thought this acronym too frivolous; Metropolis claims to have chosen the name "MANIAC" in the hope of stopping the rash of such acronyms for machine names, but may have instead further stimulated such use.) From 1957 to 1965 he was a full professor of physics at the University of Chicago and was the founding director of its Institute for Computer Research. In 1965 he returned to Los Alamos, where he was made a laboratory senior fellow in 1980.

At Los Alamos in the late 1940s and early 1950s a group of researchers led by Metropolis, including John von Neumann and Stanislaw Ulam, developed the Monte Carlo method. This is a class of computational approaches that rely on repeated random sampling to compute their results, named in reference to Ulam's relative's love for the casinos of Monte Carlo. Metropolis was deeply involved in the very first use of the Monte Carlo method, rewiring the ENIAC computer to perform simulations of a nuclear core in 1948. In 1953 Metropolis was credited as a co-author of a paper entitled Equation of State Calculations by Fast Computing Machines. This landmark paper showed the first numerical simulations of a liquid and introduced a new Monte Carlo computational method for doing so.

In applications of the Monte Carlo method to problems in statistical mechanics prior to the introduction of the Metropolis algorithm, a large number of random configurations of the system would be generated, the properties of interest (such as energy or density) would be computed for each configuration, and then a weighted average computed where the weight of each configuration was its Boltzmann factor, ${\displaystyle e^{-E/kT}}$, where ${\displaystyle E}$ is the energy, ${\displaystyle T}$ is the temperature, and ${\displaystyle k}$ is the Boltzmann constant. The key contribution of the paper was the idea that

Instead of choosing configurations randomly, then weighting them with exp(−E/kT), we choose configurations with a probability exp(−E/kT) and weight them evenly.