Paul Felix Nemenyi (June 5, 1895 – March 1, 1952) was a Hungarian mathematician and physicist specializing in continuum mechanics. Nemenyi's mathematical research encompassed: continuum mechanics, fluid dynamics, hydrostatics, statistical mechanics, non-equilibrium thermodynamics and stress mechanics. Nemenyi was known for using what he called the inverse or semi-inverse approach, which applied vector field analysis, to obtain numerous exact solutions of the nonlinear equations of gas dynamics, many of them representing rotational flows of nonuniform total energy. In continuum mechanics, "Nemenyi's theorem" proves that, given any net of isothermal curves, there exists a five parameter family of plane stress systems for which these curves are stress trajectories. He was the father of the statistician Peter Nemenyi and probably the father of former World Chess Champion Bobby Fischer.


Neményi was born to a wealthy Hungarian Jewish family on June 5, 1895 in Rijeka. His grandfather was Siegmund/Zsigmond Neményi. His father Desiderius Nemenyi was one of the directors at Rijeka Refinery (now INA d.d.). Nemenyi attended elementary and high school in Rijeka. He graduated from high school in Budapest.[1] Nemenyis uncle was Dr. Ambrus Neményi, born in Pécel, c. 20 km east of Budapest. The family's name was Neumann until 1871 when they magyarized it to Neményi. Paul Nemenyi's aunt was Berta Koppély (Whose parents were Adolf Koppély (1809-1883) and Rozsa von Hatvany-Deutsch). His family's art collection included works by Klimt, Kandinsky and Matisse.

At the age of 17, Nemenyi won the Hungarian national mathematics competition.[2] Nemenyi obtained his doctorate in mathematics in Berlin in 1922 and lectured on fluid dynamics at the Technical University of Berlin.[3] In the early 1930s, he published a textbook on mathematical mechanics that became required reading in German universities. Stripped of his position when the Nazis came to power, he also had to leave Hungary where anti-Semitic laws had been enacted, and found work for a time in Copenhagen.

He arrived in the USA at the outbreak of World War II. He briefly held a number of teaching positions in succession and took part in hydraulic research at the State University of Iowa.[4] In 1941 he was appointed instructor at the University of Colorado, and in 1944 at the State College of Washington.[5]

In Germany, Nemenyi belonged to a Socialist party called the ISK, which believed that truth could be arrived at through neo-Kantian Socratic principles. He was an animal-rights supporter, a strict vegan and refused to wear anything made of wool.[6] In 1930, Nemenyi entrusted his 3 year old first son, Peter Nemenyi, to be looked after by the socialist vegetarian community, visiting him once a year.[7]

Theodore von Kármán wrote of Nemenyi: "When he came to this country, he went to scientific meetings in an open shirt without a tie and was very much disappointed as I advised him to dress as anyone else. He told me that he thought this was a country of freedom, and the man is only judged according to his internal values and not his external appearance."[6]

In 1947 Nemenyi was appointed a physicist with the Naval Ordnance Laboratory, White Oak, Maryland.[8] He was head of the Theoretical Mechanics Section at the laboratory and one of the country's principal authorities on elasticity and fluid dynamics. Nemenyi was best known for using what he called the inverse or semi-inverse approach to obtain numerous exact solutions of the nonlinear equations of gas dynamics, many of them representing rotational flows of nonuniform total energy. (See article by Nemenyi and Prim in "Selected list of publications" below, which is Nemenyi's most highly cited work, though it has had no citations since 1985. Exact solutions may have less practical importance since the widespread availability of computers.)

Nemenyi's scientific knowledge extended well beyond the subjects of his researches. He has been described as having "extreme[ly] versatile interests and erudition".[9] Nemenyi's interest and ability encompassed several nonscientific fields. He collected children's art and sometimes lectured upon it. In 1951, he published a critique of the entire Encyclopædia Britannica, and suggested improvements for such diverse sections as psychology and psychoanalysis.[10]

Paul Nemenyi died on March 1, 1952, at the age of 56. He was survived by two sons: Peter Nemenyi, then a student of mathematics at Princeton University,[11] and Bobby Fischer, the world chess champion.

Bobby Fischer's father?

In 2002 Nemenyi was identified as the probable biological father of world chess champion Bobby Fischer, not the man named on Fischer's birth certificate.[6][12] Additional details on their relationship were reported in 2009.[13]

Selected list of publications

  • Adolf Ludin and Paul Nemenyi, Die nordischen Wasserkräfte: Ausbau und wirtschaftliche Ausnutzung. Berlin: Julius Springer, 1930.
  • Paul Nemenyi, Wasserbauliche Strömungslehre. Barth Verlag, 1933.
  • Paul Nemenyi and Bennie N. Netser, "Relation of the Statistical Theory of Turbulence to Hydraulics", Proceedings of the American Society of Civil Engineers 66 (1940), pp. 967–979.
  • Paul Nemenyi and R. Prim. Some geometric properties of plane gas flow. JOURNAL OF MATHEMATICS AND PHYSICS Volume: 27 Issue: 2 Pages: 130-135 Published: 1948. Cited 14 times according to Science Citation Index. Last cited 1985.
  • Paul Nemenyi, "The Main Concepts and Ideas of Fluid Dynamics in their Historical Development", Archive for History of Exact Sciences 2 (1962), pp. 52–86. Posthumous publication, edited by Clifford Truesdell.


  • Science, 29 August 1952, Vol. 116. no. 3009, pp. 215–216 [1]
  • Journal of the Washington Academy of Sciences 1953, 43, pp. 62–63 [Clifford Truesdell wrote this obituary and the Science obituary, and they are virtually identical.]


  1. ^ (Croatian) Sušačka revija (Glasilo za kulturu i društvena zbivanja Hrvatskog Primorja, Kvarnerskih Otoka i Gorskog Kotara); Kim Cuculić; Bobby Fischer; stranica 10; broj 62/63, 2009.
  2. ^ Nicholas, Peter (September 21, 2009). "Chasing the king of chess". Los Angeles Times. Retrieved September 21, 2009. 
  3. ^ Arnold Dresden, "The Migration of Mathematicians", American Mathematical Monthly 49:7 (1942), p. 422. Available on Jstor to subscribers.
  4. ^ Published as "An Annotated Bibliography of Fishways", Bulletin 23 of the State University of Iowa (1941) and A. M. McLeod and Paul Nemenyi, "An Investigation of Fishways", Bulletin 24 of the State University of Iowa (1941).
  5. ^ American Mathematical Monthly 51:2 (1944), p. 108. Available through JSTOR for subscribers.
  6. ^ a b c Who was Fischer's father? – a detailed but uncited article by an amateur chess historian
  7. ^ Peter Nemenyi (1927–2002), Memories Civil Rights Movement Veterans]
  8. ^ American Mathematical Monthly 54:6 (1947), p. 361. Available through JSTOR to subscribers.
  9. ^ Gleb K. Mikhailov, "Development of Studies in the History of Elasticity Theory and Structural Mechanics", in Essays on the History of Mechanics: In Memory of Clifford Ambrose Truesdell, edited by Antonio Becchi et al. (Basel, Boston and Belin: Birkhäuser Verlag, 2003), p. 30. Available through Google books. Accessed 27 Dec. 2007.
  10. ^ Nemenyi, Paul. "Test Borings in the Britannica". New Republic. Feb. 19, 1951, p 17.
  11. ^ Obituary in Science, August 29, 1952, p. 216.
  12. ^ Nicholas, Peter, and Clea Benson. Files reveal how FBI hounded chess king. Philadelphia Inquirer. November 17, 2002
  13. ^ Nicholas, Peter (September 21, 2009), "Chasing the king of chess", The Los Angeles Times