Peter David Lax (1 May 1926 – 16 May 2025) was a Hungarian-born American mathematician and Abel Prize laureate working in the areas of pure and

applied mathematics Applied mathematics is the application of mathematics, mathematical methods by different fields such as physics, engineering, medicine, biology, finance, business, computer science, and Industrial sector, industry. Thus, applied mathematics is a ...

. Lax made important contributions to

integrable system In mathematics, integrability is a property of certain dynamical systems. While there are several distinct formal definitions, informally speaking, an integrable system is a dynamical system with sufficiently many conserved quantities, or first ...

fluid dynamics In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion ...

and

shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...

soliton In mathematics and physics, a soliton is a nonlinear, self-reinforcing, localized wave packet that is , in that it preserves its shape while propagating freely, at constant velocity, and recovers it even after collisions with other such local ...

ic physics, hyperbolic conservation laws, and mathematical and

scientific computing Computational science, also known as scientific computing, technical computing or scientific computation (SC), is a division of science, and more specifically the Computer Sciences, which uses advanced computing capabilities to understand and s ...

, among other fields. In a 1958 paper Lax stated a

conjecture In mathematics, a conjecture is a conclusion or a proposition that is proffered on a tentative basis without proof. Some conjectures, such as the Riemann hypothesis or Fermat's conjecture (now a theorem, proven in 1995 by Andrew Wiles), ha ...

about

matrix Matrix (: matrices or matrixes) or MATRIX may refer to: Science and mathematics * Matrix (mathematics), a rectangular array of numbers, symbols or expressions * Matrix (logic), part of a formula in prenex normal form * Matrix (biology), the m ...

representations for third order hyperbolic polynomials which remained unproven for over four decades. Interest in the "Lax conjecture" grew as mathematicians working in several different areas recognized the importance of its implications in their field, until it was finally proven to be true in 2003.

Life and education

Lax was born on 1 May 1926 in

Budapest Budapest is the Capital city, capital and List of cities and towns of Hungary, most populous city of Hungary. It is the List of cities in the European Union by population within city limits, tenth-largest city in the European Union by popul ...

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

, to a

Jewish Jews (, , ), or the Jewish people, are an ethnoreligious group and nation, originating from the Israelites of History of ancient Israel and Judah, ancient Israel and Judah. They also traditionally adhere to Judaism. Jewish ethnicity, rel ...

family. He began displaying an interest in mathematics at age twelve, and soon his parents hired

Rózsa Péter Rózsa Péter, until January 1934 Rózsa Politzer, (17 February 1905 – 16 February 1977) was a Hungarian mathematician and logician. She is best known as the "founding mother of recursion theory". Early life and education Péter was bor ...

as a tutor for him. His parents Klara Kornfield and Henry Lax were both physicians and his uncle Albert Kornfeld (also known as Albert Korodi) was a mathematician, as well as a friend of Leó Szilárd. The family left Hungary on 15 November 1941, and traveled via

Lisbon Lisbon ( ; ) is the capital and largest city of Portugal, with an estimated population of 567,131, as of 2023, within its administrative limits and 3,028,000 within the Lisbon Metropolitan Area, metropolis, as of 2025. Lisbon is mainlan ...

to the United States. As a high school student at

Stuyvesant High School Stuyvesant High School ( ) is a co-ed, State school, public, college-preparatory, Specialized high schools in New York City, specialized high school in Manhattan, New York City. The school, commonly called "Stuy" ( ) by its students, faculty, a ...

, Lax took no math classes but did compete on the school math team. During this time, he met with

John von Neumann John von Neumann ( ; ; December 28, 1903 – February 8, 1957) was a Hungarian and American mathematician, physicist, computer scientist and engineer. Von Neumann had perhaps the widest coverage of any mathematician of his time, in ...

Richard Courant Richard Courant (January 8, 1888 – January 27, 1972) was a German-American mathematician. He is best known by the general public for the book '' What is Mathematics?'', co-written with Herbert Robbins. His research focused on the areas of real ...

, and

Paul Erdős Paul Erdős ( ; 26March 191320September 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 discrete mathematics, g ...

, who introduced him to

Albert Einstein Albert Einstein (14 March 187918 April 1955) was a German-born theoretical physicist who is best known for developing the theory of relativity. Einstein also made important contributions to quantum mechanics. His mass–energy equivalence f ...

. As he was still 17 when he finished high school, he could avoid military service, and was able to study for three semesters at

New York University New York University (NYU) is a private university, private research university in New York City, New York, United States. Chartered in 1831 by the New York State Legislature, NYU was founded in 1832 by Albert Gallatin as a Nondenominational ...

. He attended a

complex analysis Complex analysis, traditionally known as the theory of functions of a complex variable, is the branch of mathematical analysis that investigates functions of complex numbers. It is helpful in many branches of mathematics, including algebraic ...

class in the role of a student, but ended up taking over as instructor. He met his future wife, Anneli Cahn (married to her first husband at that time) in this class. Before being able to complete his studies, Lax was drafted into the U.S. Army. After basic training, the Army sent him to

Texas A&M University Texas A&M University (Texas A&M, A&M, TA&M, or TAMU) is a public university, public, Land-grant university, land-grant, research university in College Station, Texas, United States. It was founded in 1876 and became the flagship institution of ...

for more studies. He was then sent to

Oak Ridge National Laboratory Oak Ridge National Laboratory (ORNL) is a federally funded research and development centers, federally funded research and development center in Oak Ridge, Tennessee, United States. Founded in 1943, the laboratory is sponsored by the United Sta ...

, and soon afterwards to the

Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...

at Los Alamos,

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

. At Los Alamos, he began working as a calculator operator, but eventually moved on to higher-level mathematics. After the war ended, he remained with the Army at Los Alamos for another year, while taking courses at the

University of New Mexico The University of New Mexico (UNM; ) is a public research university in Albuquerque, New Mexico, United States. Founded in 1889 by the New Mexico Territorial Legislature, it is the state's second oldest university, a flagship university in th ...

, then studied at

Stanford University Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth ...

for a semester with

Gábor Szegő Gábor Szegő () (January 20, 1895 – August 7, 1985) was a Hungarian-American mathematician. He was one of the foremost mathematical analysts of his generation and made fundamental contributions to the theory of orthogonal polynomials and ...

and

George Pólya George Pólya (; ; December 13, 1887 – September 7, 1985) was a Hungarian-American mathematician. He was a professor of mathematics from 1914 to 1940 at ETH Zürich and from 1940 to 1953 at Stanford University. He made fundamental contributi ...

. Lax returned to NYU for the 1946–1947 academic year, and by pooling credits from the four universities at which he had studied, he graduated that year. He stayed at NYU for his graduate studies, marrying Anneli in 1948 and earning a PhD in 1949 under the supervision of Kurt O. Friedrichs.. In 1954, the U.S. Atomic Energy Commission put Lax and several of his colleagues at NYU in charge of using an early supercomputer to calculate the risk of flooding for a major nuclear reactor if a nearby dam were sabotaged; they concluded that the reactor would be safe. Lax made contributions to the theory of

hyperbolic partial differential equation In mathematics, a hyperbolic partial differential equation of order n is a partial differential equation (PDE) that, roughly speaking, has a well-posed initial value problem for the first n - 1 derivatives. More precisely, the Cauchy problem can ...

s. He made breakthroughs in understanding

s from bombs,

weather prediction Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the ...

and aerodynamic design. Concepts that bear Lax's name include the Lax equivalence principle, which explained when numerical computer approximations would be reliable, and Lax pairs, which are helpful in understanding the motion of

s. With Ralph Phillips, Lax developed the Lax-Phillips semigroup in

scattering theory In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...

, which explained how

wave In physics, mathematics, engineering, and related fields, a wave is a propagating dynamic disturbance (change from List of types of equilibrium, equilibrium) of one or more quantities. ''Periodic waves'' oscillate repeatedly about an equilibrium ...

s move around obstacles and showed how to use the pattern of a wave's frequencies to understand its motion. That theory is helpful in processing radar signals. Lax held a faculty position in the Department of Mathematics,

Courant Institute of Mathematical Sciences The Courant Institute of Mathematical Sciences (commonly known as Courant or CIMS) is the mathematics research school of New York University (NYU). Founded in 1935, it is named after Richard Courant, one of the founders of the Courant Institute ...

. Beginning in 1963, Dr. Lax directed the Courant Institute's computing facilities. Lax died of cardiac amyloidosis at his Manhattan home, on 16 May 2025, at the age of 99.

Awards and honors

He was a member of the

Norwegian Academy of Science and Letters The Norwegian Academy of Science and Letters (, DNVA) is a learned society based in Oslo, Norway. Its purpose is to support the advancement of science and scholarship in Norway. History The Royal Frederick University in Christiania was establis ...

and the National Academy of Sciences, USA, the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

, and the

American Philosophical Society The American Philosophical Society (APS) is an American scholarly organization and learned society founded in 1743 in Philadelphia that promotes knowledge in the humanities and natural sciences through research, professional meetings, publicat ...

. He won a

Lester R. Ford Award ''The American Mathematical Monthly'' is a peer-reviewed scientific journal of mathematics. It was established by Benjamin Finkel in 1894 and is published by Taylor & Francis on behalf of the Mathematical Association of America. It is an expositor ...

in 1966 and again in 1973. In 1974, his shock wave article also won the Chauvenet Prize. He was awarded the

National Medal of Science The National Medal of Science is an honor bestowed by the President of the United States to individuals in science and engineering who have made important contributions to the advancement of knowledge in the fields of behavioral science, behavior ...

in 1986, the

Wolf Prize The Wolf Prize is an international award granted in Israel, that has been presented most years since 1978 to living scientists and artists for "achievements in the interest of mankind and friendly relations among people ... irrespective of natio ...

in 1987, the Abel Prize in 2005 and the

Lomonosov Gold Medal The Lomonosov Gold Medal ( ''Bol'shaya zolotaya medal' imeni M. V. Lomonosova''), named after Russian scientist and polymath Mikhail Lomonosov, is awarded each year since 1959 for outstanding achievements in the natural sciences and the humaniti ...

in 2013. The

American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...

selected him as its Gibbs Lecturer for 2007. In 2012, he became a fellow of the

. Lax is listed as an ISI highly cited researcher. According to

György Marx György Marx (25 May 1927 – 2 December 2002) was a Hungarian physicist, astrophysicist, science historian and professor. He discovered the lepton numbers and established the Lepton number#Lepton flavor conservation, law of lepton flavor conse ...

he was one of The Martians. Lax also received an Honorary Doctorate from

Heriot-Watt University Heriot-Watt University () is a public research university based in Edinburgh, Scotland. It was established in 1821 as the School of Arts of Edinburgh, the world's first mechanics' institute, and was subsequently granted university status by roya ...

in 1990.

The CDC 6600 incident

In 1970, as part of an anti-war protest, the Transcendental Students took hostage a

CDC 6600 The CDC 6600 was the flagship of the 6000 series of mainframe computer systems manufactured by Control Data Corporation. Generally considered to be the first successful supercomputer, it outperformed the industry's prior recordholder, the I ...

super computer at NYU's Courant Institute which Lax had been instrumental in acquiring; the students demanded $100,000 in ransom () to provide bail for a member of the

Black Panthers The Black Panther Party (originally the Black Panther Party for Self-Defense) was a Marxist–Leninist and black power political organization founded by college students Bobby Seale and Huey P. Newton in October 1966 in Oakland, California ...

. Some of the students present attempted to destroy the computer with incendiary devices, but Lax and colleagues managed to disable the devices and save the machine.

Books

* * * * * ''Decay of Solutions of Systems of Nonlinear Hyperbolic Conservation Laws'', with J. Glimm, American Mathematical Society (1970). * (Review) * * * * * * * * * * *

Notes

External links

2016 Video Interview with Peter Lax by Atomic Heritage Foundation
Voices of the Manhattan Project * *
Elements from his contributions to mathematics
Popularised presentation of Peter Lax by Helge Holden, published on the Abel Prize website.
Abel Prize press release and biography
* * {{DEFAULTSORT:Lax, Peter 1926 births 2025 deaths Members of the United States National Academy of Sciences Abel Prize laureates 20th-century American mathematicians 20th-century Hungarian mathematicians 21st-century American mathematicians 21st-century Hungarian mathematicians Hungarian emigrants to the United States American people of Hungarian-Jewish descent Jews who emigrated to escape Nazism Hungarian Jews Members of the Norwegian Academy of Science and Letters Foreign members of the USSR Academy of Sciences Foreign members of the Russian Academy of Sciences National Medal of Science laureates Courant Institute of Mathematical Sciences alumni Courant Institute of Mathematical Sciences faculty Numerical analysts Stuyvesant High School alumni Wolf Prize in Mathematics laureates Members of the French Academy of Sciences Fluid dynamicists Fellows of the American Mathematical Society Fellows of the Society for Industrial and Applied Mathematics Presidents of the American Mathematical Society Recipients of the Lomonosov Gold Medal Partial differential equation theorists American textbook writers Mathematicians from New York (state) United States Army personnel of World War II Members of the American Philosophical Society Deaths from amyloidosis