The Monte Carlo trolley, or FERMIAC, was an analog computer invented by physicist Enrico Fermi to aid in his studies of neutron transport. [1]
The Monte Carlo trolley, or FERMIAC, was an analog computer invented by physicist Enrico Fermi to aid in his studies of neutron transport. [1]
The FERMIAC employed the Monte Carlo method to model neutron transport in various types of nuclear systems. Given an initial distribution of neutrons, the goal of the process is to develop numerous "neutron genealogies", or models of the behavior of individual neutrons, including each collision, scattering, and fission. When a fission occurs, the number of emerging neutrons is predicted, and the behavior of each of these neutrons is eventually modeled in the same manner as the first. At each stage, pseudo-random numbers are used to make decisions that affect the behavior of each neutron.
The FERMIAC used this method to create two-dimensional neutron genealogies on a scale diagram of a nuclear device. A series of drums on the device were set according to the material being crossed and a random choice between fast and slow neutrons. Random numbers also determined the direction of travel and the distance until the next collision. Once the drums were set, the trolley was rolled across the diagram, drawing a path as it went. Any time a change in material was indicated on the diagram, the drum settings were adjusted accordingly before continuing.
In the early 1930s, Italian physicist Enrico Fermi led a team of young scientists, dubbed the "Via Panisperna boys", in their now-famous experiments in nuclear physics. During this time, Fermi developed "statistical sampling" techniques that he effectively employed to predict the results of experiments. [2]
Years later, in 1946, Fermi participated in the initial review of results from the ENIAC. Among the others present was Los Alamos mathematician Stanislaw Ulam, who was familiar with the use of statistical sampling techniques similar to those previously developed by Fermi. Such techniques had mainly fallen out of use, due to the long, repetitious calculations required. However, given ENIAC's powers of calculation, Ulam saw an opportunity to resurrect these techniques. He discussed his ideas with John von Neumann, who eventually used the ENIAC to implement the Monte Carlo method (as the statistical sampling techniques came to be called) to solve a variety of neutron transport problems. [3]
However, before the ENIAC could be employed for this purpose, it first had to be moved to its permanent home at the Ballistics Research Laboratory. [4] It was during this interruption in ENIAC operation that Fermi came up with the idea for his analog device. He enlisted his colleague L.D.P. King to build the instrument, which was later given the fitting name FERMIAC. The device was used for approximately two years. [5]
In 2015, the Museo Storico della Fisica e Centro Studi e Ricerche "Enrico Fermi" created a replica of the device. [6] [7]
Enrico Fermi was an Italian and later naturalized American physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and the "architect of the atomic bomb". He was one of very few physicists to excel in both theoretical physics and experimental physics. Fermi was awarded the 1938 Nobel Prize in Physics for his work on induced radioactivity by neutron bombardment and for the discovery of transuranium elements. With his colleagues, Fermi filed several patents related to the use of nuclear power, all of which were taken over by the US government. He made significant contributions to the development of statistical mechanics, quantum theory, and nuclear and particle physics.
Stanisław Marcin Ulam was a Polish-American mathematician and nuclear physicist. He participated in the Manhattan Project, originated the Teller–Ulam design of thermonuclear weapons, discovered the concept of the cellular automaton, invented the Monte Carlo method of computation, and suggested nuclear pulse propulsion. In pure and applied mathematics, he proved some theorems and proposed several conjectures.
Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be deterministic in principle. They are often used in physical and mathematical problems and are most useful when it is difficult or impossible to use other approaches. Monte Carlo methods are mainly used in three problem classes: optimization, numerical integration, and generating draws from a probability distribution.
The MANIAC I was an early computer built under the direction of Nicholas Metropolis at the Los Alamos Scientific Laboratory. It was based on the von Neumann architecture of the IAS, developed by John von Neumann. As with all computers of its era, it was a one-of-a-kind machine that could not exchange programs with other computers. Metropolis chose the name MANIAC in the hope of stopping the rash of silly acronyms for machine names, although von Neumann may have suggested the name to him.
Stochastic refers to the property of being well described by a random probability distribution. Although stochasticity and randomness are distinct in that the former refers to a modeling approach and the latter refers to phenomena themselves, these two terms are often used synonymously. Furthermore, in probability theory, the formal concept of a stochastic process is also referred to as a random process.
Nicholas Constantine Metropolis was a Greek-American physicist.
A thermonuclear weapon, fusion weapon or hydrogen bomb is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 or plutonium-239. The first full-scale thermonuclear test was carried out by the United States in 1952; the concept has since been employed by most of the world's nuclear powers in the design of their weapons.
Monte Carlo N-Particle Transport (MCNP) is a general-purpose, continuous-energy, generalized-geometry, time-dependent, Monte Carlo radiation transport code designed to track many particle types over broad ranges of energies and is developed by Los Alamos National Laboratory. Specific areas of application include, but are not limited to, radiation protection and dosimetry, radiation shielding, radiography, medical physics, nuclear criticality safety, detector design and analysis, nuclear oil well logging, accelerator target design, fission and fusion reactor design, decontamination and decommissioning. The code treats an arbitrary three-dimensional configuration of materials in geometric cells bounded by first- and second-degree surfaces and fourth-degree elliptical tori.
Aqueous homogeneous reactors (AHR) are a type of nuclear reactor in which soluble nuclear salts are dissolved in water. The fuel is mixed with the coolant and the moderator, thus the name "homogeneous". The water can be either heavy water or ordinary (light) water, both of which need to be very pure.
Stanley Phillips Frankel was an American computer scientist. He worked in the Manhattan Project and developed various computers as a consultant.
Anthony Leonid Turkevich was an American radiochemist who was the first to determine the composition of the Moon's surface using an alpha scattering spectrometer on the Surveyor 5 mission in 1967.
Computational statistics, or statistical computing, is the bond between statistics and computer science. It means statistical methods that are enabled by using computational methods. It is the area of computational science specific to the mathematical science of statistics. This area is also developing rapidly, leading to calls that a broader concept of computing should be taught as part of general statistical education.
Herbert Lawrence Anderson was an American nuclear physicist who was Professor of Physics at the University of Chicago.
"Equation of State Calculations by Fast Computing Machines" is a scholarly article published by Nicholas Metropolis, Arianna W. Rosenbluth, Marshall N. Rosenbluth, Augusta H. Teller, and Edward Teller in the Journal of Chemical Physics in 1953. This paper proposed what became known as the Metropolis Monte Carlo algorithm, which forms the basis for Monte Carlo statistical mechanics simulations of atomic and molecular systems.
The following timeline starts with the invention of the modern computer in the late interwar period.
The following is a timeline of scientific computing, also known as computational science.
Mary Tsingou is an American physicist and mathematician of Greek descent. She was one of the first programmers on the MANIAC computer at Los Alamos National Laboratory and is best known for having coded the celebrated computer experiment with Enrico Fermi, John Pasta, and Stanislaw Ulam which became an inspiration for the fields of chaos theory and scientific computing and was a turning point in soliton theory.
The following is a timeline of numerical analysis after 1945, and deals with developments after the invention of the modern electronic computer, which began during Second World War. For a fuller history of the subject before this period, see timeline and history of mathematics.
This is a timeline of key developments in computational mathematics.
The Los Alamos Laboratory, also known as Project Y, was a secret laboratory established by the Manhattan Project and operated by the University of California during World War II. Its mission was to design and build the first atomic bombs. Robert Oppenheimer was its first director, serving from 1943 to December 1945, when he was succeeded by Norris Bradbury. In order to enable scientists to freely discuss their work while preserving security, the laboratory was located in a remote part of New Mexico. The wartime laboratory occupied buildings that had once been part of the Los Alamos Ranch School.