André Bloch (mathematician)

André Bloch (20 November 1893 – 11 October 1948) was a Jewish-French mathematician who is best remembered for a result called Bloch's theorem.[1] Bloch was institutionalized in a mental asylum for thirty-one years of his life, during which all of his mathematical output was produced.[2]

Early life

Bloch was born in 1893 in Besançon, France. According to one of his teachers, Georges Valiron, both André Bloch and his younger brother Georges were the same class in October 1910. Valiron believed Georges to have the better talent, and due to lack of preparation, André finished last in the class. André was spared from failing the class by convincing Ernest Vessiot to give him an oral exam. The exam convinced Vessiot of Andre's talent and both André and Georges entered the École Polytechnique.[3][4]

Both brothers served for a year in the military prior to World War I.[5] Both André and Georges studied for only one year at the École Polytechnique before the outbreak of the war.[5]
World War I

Upon the outbreak of World War I in 1914, André and Georges Bloch were drafted. André, as a second-lieutenant in the artillery, was assigned to the headquarters of General De Castelnau in Nancy.[5]

Both Bloch brothers were injured: André suffered from a fall from an observation post, while Georges sustained a head wound which cost him an eye [5]. Georges was released from service and returned to the École Polytechnique on 7 October 1917.[4] André, however, was allowed to convalesce but not released from duty.
Murder

On 17 November 1917, while on convalescent leave from service in World War I, Bloch killed his brother Georges, and his aunt and uncle.[2] Several motives are given by mathematicians for Bloch's crime.[6] However, Cartan and Ferrand quote Henri Baruk, who was the medical head of the asylum where Bloch was confined. Bloch told Baruk that the murders were a eugenic act, in order to eliminate branches of his family affected by mental illness.[5]
Commitment and mathematical career

After the murders, Bloch was committed to the asylum at Charenton in Saint Maurice,[5] a suburb of Paris. Bloch continued his mathematical career while confined. All of his publications, including those relating to Bloch's constant, were written while he was committed. Bloch corresponded with several mathematicians, including Georges Valiron, George Pólya, Jacques Hadamard and others,[5] giving his return address as only "57 Grande rue, Saint-Maurice", never mentioning that this was a psychiatric hospital. Several of his correspondents were thus unaware of his situation.[5]

During the German occupation of France during World War II, Bloch (who was Jewish) wrote under aliases, in order to avoid advertising his presence to Nazi occupiers. In particular, Bloch is known to have authored papers under the names of René Binaud and Marcel Segond during this time.[4]

According to Pólya, Bloch had the habit of dating his letters with 1 April,[4] regardless of when they were written.

Bloch was transferred to the Saint Anne's Hospital in Paris on 21 August 1948 for an operation. He died from leukemia in Paris on 11 October 1948.[5]
Bloch's theorem

Bloch is the namesake of Bloch's theorem. This result defines a numerical value which is referred to as "Bloch's constant".[7] While Bloch provided in 1925 estimates of this constant (namely, that it was at least 1/72 [7]), to date, the exact value of Bloch's constant is unknown.

See also

Bloch space

Notes

^ This usage should not to be confused with the results of Swiss physicist Felix Bloch, which are sometimes called "Bloch's Theorem".
^ a b O'Connor, John J.; Robertson, Edmund F. (December 1996), "Andre Bloch", MacTutor History of Mathematics archive, University of St Andrews.
^ G. Valiron, Des Théorèmes de Bloch aux Théories d'Ahlfors, Bulletin des Sciences Mathematiques 73 (1949) 152–162.
^ a b c d D. Campbell, Beauty and the beast: The strange case of André Bloch, The Mathematical Intelligencer 7 (1985) 36–38.
^ a b c d e f g h i H. Cartan and J. Ferrand, "The Case of André Bloch", The Mathematical Intelligencer 10 (1988) 23–26.
^ See the article by Campbell for several anecdotal examples. Cartan and Ferrand note that "certain of these conjectures are outrageously eccentric". Krantz ("Mathematical Apocrypha: Stories and Anecdotes of Mathematicians and the Mathematical", American Mathematical Society, 2002) also lists some conjectures.
^ a b Weisstein, Eric W., "Bloch Constant" from MathWorld.

External links

Bloch's Constant at PlanetMath
Bloch's Theorem at PlanetMath