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Edward Nelson (May 4, 1932 – September 10, 2014) was an American mathematician. He was professor in the Mathematics Department at Princeton University. He was known for his work on mathematical physics and mathematical logic. In mathematical logic, he was noted especially for his
internal set theory Internal set theory (IST) is a mathematical theory of sets developed by Edward Nelson that provides an axiomatic basis for a portion of the nonstandard analysis introduced by Abraham Robinson. Instead of adding new elements to the real numbers, Ne ...
, and views on ultrafinitism and the consistency of
arithmetic Arithmetic () is an elementary part of mathematics that consists of the study of the properties of the traditional operations on numbers— addition, subtraction, multiplication, division, exponentiation, and extraction of roots. In the 19th ...
. In philosophy of mathematics he advocated the view of formalism rather than platonism or
intuitionism In the philosophy of mathematics, intuitionism, or neointuitionism (opposed to preintuitionism), is an approach where mathematics is considered to be purely the result of the constructive mental activity of humans rather than the discovery of fu ...
. He also wrote on the relationship between religion and mathematics.


Biography

Edward Nelson was born in
Decatur, Georgia Decatur is a city in, and the county seat of, DeKalb County, Georgia, which is part of the Atlanta metropolitan area. With a population of 24,928 in the 2020 census, the municipality is sometimes assumed to be larger since multiple ZIP Codes in ...
, in 1932. He spent his early childhood in Rome where his father worked for the Italian YMCA. At the advent of World War II, Nelson moved with his mother to New York City, where he attended high school at the Bronx High School of Science. His father, who spoke fluent Russian, stayed in St. Petersburg in connection with issues related to
prisoners of war A prisoner of war (POW) is a person who is held Captivity, captive by a belligerent power during or immediately after an armed conflict. The earliest recorded usage of the phrase "prisoner of war" dates back to 1610. Belligerents hold priso ...
. After the war, his family returned to Italy and he attended the Liceo Scientifico Giovanni Verga in Rome. He received his Ph.D. in 1955 from the University of Chicago, where he worked with
Irving Segal Irving Ezra Segal (1918–1998) was an American mathematician known for work on theoretical quantum mechanics. He shares credit for what is often referred to as the Segal–Shale–Weil representation. Early in his career Segal became known for h ...
. He was a member of the Institute for Advanced Study from 1956 to 1959. He held a position at Princeton University starting in 1959, attaining the rank of professor there in 1964 and retiring in 2013. In 2012 he became a fellow of the American Mathematical Society. He died in Princeton, New Jersey, on September 10, 2014.


Academic work


Stochastic quantum mechanics

Nelson made contributions to the theory of infinite-dimensional group representations, the mathematical treatment of
quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and ...
, the use of
stochastic process In probability theory and related fields, a stochastic () or random process is a mathematical object usually defined as a family of random variables. Stochastic processes are widely used as mathematical models of systems and phenomena that appea ...
es in quantum mechanics, and the reformulation of probability theory in terms of non-standard analysis. For many years he worked on mathematical physics and probability theory, and he retained a residual interest in these fields, particularly in connection with possible extensions of stochastic mechanics to field theory.


Four color problem

In 1950, Nelson formulated a popular variant of the four color problem: What is the chromatic number, denoted \chi, of the plane? In more detail, what is the smallest number of colors sufficient for coloring the points of the Euclidean plane such that no two points of the same color are unit distance apart? We know by simple arguments that 4 ≤ ''χ'' ≤ 7. The problem was introduced to a wide mathematical audience by Martin Gardner in his October 1960 Mathematical Games column. The chromatic number problem, also now known as the Hadwiger–Nelson problem, was a favorite of
Paul Erdős Paul Erdős ( hu, Erdős Pál ; 26 March 1913 – 20 September 1996) was a Hungarian mathematician. He was one of the most prolific mathematicians and producers of mathematical conjectures of the 20th century. pursued and proposed problems in ...
, who mentioned it frequently in his problems lectures. In 2018, Aubrey de Grey showed that ''χ'' ≥ 5..


Foundations of mathematics

In the later part of his career, he worked on mathematical logic and the foundations of mathematics. One of his goals was to extend IST (
Internal Set Theory Internal set theory (IST) is a mathematical theory of sets developed by Edward Nelson that provides an axiomatic basis for a portion of the nonstandard analysis introduced by Abraham Robinson. Instead of adding new elements to the real numbers, Ne ...
—a version of a portion of Abraham Robinson's non-standard analysis) in a natural manner that includes external functions and sets, in a way that provides an external function with specified properties unless there is a finitary obstacle to its existence. Other work centered on fragments of arithmetic, studying the divide between those theories interpretable in Raphael Robinson's arithmetic and those that are not;
computational complexity In computer science, the computational complexity or simply complexity of an algorithm is the amount of resources required to run it. Particular focus is given to computation time (generally measured by the number of needed elementary operations) ...
, including the problem of whether P is equal to NP or not; and
automated proof checking In computer science and mathematical logic, a proof assistant or interactive theorem prover is a software tool to assist with the development of formal proofs by human-machine collaboration. This involves some sort of interactive proof editor ...
. In September 2011, Nelson announced that he had proved that
Peano arithmetic In mathematical logic, the Peano axioms, also known as the Dedekind–Peano axioms or the Peano postulates, are axioms for the natural numbers presented by the 19th century Italian mathematician Giuseppe Peano. These axioms have been used nearly u ...
was logically inconsistent. An error was found in the proof by
Terence Tao Terence Chi-Shen Tao (; born 17 July 1975) is an Australian-American mathematician. He is a professor of mathematics at the University of California, Los Angeles (UCLA), where he holds the James and Carol Collins chair. His research includes ...
, and Nelson retracted the claim.


Publications


Selected papers

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Books

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See also

*
Hidden variable theory In physics, hidden-variable theories are proposals to provide explanations of quantum mechanical phenomena through the introduction of (possibly unobservable) hypothetical entities. The existence of fundamental indeterminacy for some measurem ...
*
Influence of non-standard analysis Abraham Robinson's theory of nonstandard analysis has been applied in a number of fields. Probability theory "Radically elementary probability theory" of Edward Nelson combines the discrete and the continuous theory through the infinitesimal appro ...
*
Stochastic process In probability theory and related fields, a stochastic () or random process is a mathematical object usually defined as a family of random variables. Stochastic processes are widely used as mathematical models of systems and phenomena that appea ...
* Stochastic quantum mechanics *
Stochastic electrodynamics Stochastic electrodynamics (SED) is a variant of classical electrodynamics (CED) of theoretical physics. SED consists of a set of controversial theories that posit the existence of a classical Lorentz invariant radiation field having statisti ...


References


Notes


Sources

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External links


Curriculum Vitae – Edward Nelson

Mathematics and Faith – Edward Nelson

Edward Nelson's Homepage
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Mathematics and Religion Discussion

The Limitation of Mental and Physical Reality Discussion
{{DEFAULTSORT:Nelson, Edward 1932 births Members of the United States National Academy of Sciences Fellows of the American Mathematical Society 20th-century American mathematicians 21st-century American mathematicians American logicians Set theorists University of Chicago alumni Princeton University faculty 2014 deaths American mathematical physicists