Peter Lax | |
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 Lax in Tokyo in 1969 | |
| Born | Péter Dávid Lax (1926-05-01)1 May 1926 |
| Died | 16 May 2025(2025-05-16) (aged 99) New York City, U.S. |
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| Fields | Mathematics |
| Institutions | Courant Institute |
| Thesis | Nonlinear System of Hyperbolic Partial Differential Equations in Two Independent Variables (1949) |
| Doctoral advisor | K. O. Friedrichs |
| Doctoral students | |
Peter David Lax (1 May 1926 – 16 May 2025) was a Hungarian-born American mathematician andAbel Prize laureate working in the areas ofpure andapplied mathematics.
Lax made important contributions tointegrable systems,fluid dynamics andshock waves,solitonic physics,hyperbolic conservation laws, and mathematical andscientific computing, among other fields. In a 1958 paper Lax stated aconjecture aboutmatrix 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.[1]
Lax was born on 1 May 1926 inBudapest,Hungary,[2] to aJewish family.[3] He began displaying an interest in mathematics at age twelve, and soon his parents hiredRózsa Péter as a tutor for him.[4] 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 ofLeó Szilárd. The family left Hungary on 15 November 1941, and traveled viaLisbon to the United States.
As a high school student atStuyvesant High School, Lax took no math classes but did compete on the school math team. During this time, he met withJohn von Neumann,Richard Courant, andPaul Erdős, who introduced him toAlbert Einstein. As he was still 17 when he finished high school, he could avoid military service, and was able to study for three semesters atNew York University. He attended acomplex analysis 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.[4][5]
Before being able to complete his studies, Lax was drafted into the U.S. Army. After basic training, the Army sent him toTexas A&M University for more studies. He was then sent toOak Ridge National Laboratory, and soon afterwards to theManhattan Project atLos Alamos,New Mexico. At Los Alamos, he began working as a calculator operator, but eventually moved on to higher-level mathematics.[6]
After the war ended, Lax remained with the Army at Los Alamos for another year, while taking courses at theUniversity of New Mexico, then studied atStanford University for a semester withGábor Szegő andGeorge Pólya.[4] 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 ofKurt O. Friedrichs.[4][5]
In 1954, theU.S. Atomic Energy Commission put Lax and several of his colleagues at NYU in charge of using an earlysupercomputer 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.[2]
Lax made contributions to the theory ofhyperbolic partial differential equations. He made breakthroughs in understandingshock waves from bombs,weather prediction andaerodynamic design.[2]
Concepts that bear Lax's name include the Lax equivalence principle, which explained when numerical computer approximations would be reliable, andLax pairs, which are helpful in understanding the motion ofsolitons. WithRalph Phillips, Lax developed the Lax-Phillips semigroup inscattering theory, which explained howwaves move around obstacles and showed how to use the pattern of a wave's frequencies to understand its motion. That theory is helpful inprocessing radar signals.[2]
Lax held a faculty position in the Department of Mathematics,Courant Institute of Mathematical Sciences,New York University.[7] Beginning in 1963, Dr. Lax directed the Courant Institute's computing facilities.[2]
Lax died ofcardiac amyloidosis at his Manhattan home, on 16 May 2025, at the age of 99.[2]
He was a member of theNorwegian Academy of Science and Letters[8] and theNational Academy of Sciences, USA,[9] theAmerican Academy of Arts and Sciences,[10] and theAmerican Philosophical Society.[11] He won aLester R. Ford Award in 1966[12] and again in 1973.[13] In 1974, his shock wave article[13] also won theChauvenet Prize. He was awarded theNational Medal of Science in 1986, theWolf Prize in 1987, theAbel Prize in 2005 and theLomonosov Gold Medal in 2013.[14] TheAmerican Mathematical Society selected him as its Gibbs Lecturer for 2007.[15] In 2012, he became a fellow of theAmerican Mathematical Society.[16]
Lax is listed as anISI highly cited researcher.[17] According toGyörgy Marx he was one ofThe Martians.[18]
Lax also received an Honorary Doctorate fromHeriot-Watt University in 1990.[19]
In 1970, as part of an anti-war protest, theTranscendental Students took hostage aCDC 6600super computer atNYU'sCourant Institute which Lax had been instrumental in acquiring; the students demanded $100,000 in ransom (equivalent to $810,000 in 2024) to provide bail for a member of theBlack Panthers. 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.[20][21]
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