Pascual Jordan | |
|---|---|
 Pascual Jordan in the 1920s | |
| Born | Ernst Pascual Jordan 18 October 1902 |
| Died | 31 July 1980(1980-07-31) (aged 77) |
| Education | Technical University of Hannover University of Göttingen |
| Known for | Quantum mechanics Quantum field theory Canonical commutation relation Matrix mechanics Neutrino theory of light Zero-energy universe Skew lattice Jordan algebra Jordan–Brans–Dicke theory Jordan and Einstein frames Jordan map Jordan–Wigner transformation Pauli–Jordan function |
| Awards | Ackermann–Teubner Memorial Award (1937) Max Planck Medal (1942) Konrad Adenauer Prize (1971) |
| Scientific career | |
| Fields | Theoretical physics |
| Institutions | University of Rostock University of Berlin University of Hamburg |
| Doctoral advisor | Max Born |
| Doctoral students | Jürgen Ehlers Engelbert Schücking Wolfgang Kundt |
Ernst Pascual Jordan (German:[ˈɛʁnstpasˈku̯alˈjɔʁdaːn]; 18 October 1902 – 31 July 1980) was a German theoretical and mathematicalphysicist who made significant contributions toquantum mechanics andquantum field theory. He contributed much to the mathematical form ofmatrix mechanics, and developedcanonical anticommutation relations forfermions. He introducedJordan algebras in an effort to formalize quantum field theory; the algebras have since found numerous applications within mathematics.[1]
Jordan joined theNazi Party in 1933, but did not follow theDeutsche Physik movement, which at the time rejected quantum physics developed byAlbert Einstein and other Jewish physicists. After theSecond World War, he entered politics for the conservative partyCDU and served as a member of parliament from 1957 to 1961.
Jordan was born toErnst Pasqual Jordan (1858–1924) and Eva Fischer. Ernst Jordan was a painter renowned for his portraits and landscapes. He was an associate professor of art at Hannover Technical University when his son was born. The family name was originally Jorda and it was of Spanish origin. The first born sons were all given the name Pasqual or the version Pascual. The family settled in Hannover after Napoleon's defeat at the Battle of Waterloo in 1815 and at some stage changed their name from Jorda to Jordan. Ernst Jordan married Eva Fischer in 1892.
An ancestor of Pascual Jordan named Pascual Jordan[2] was a Spanish nobleman and cavalry officer who served with the British during and after theNapoleonic Wars. Jordan eventually settled inHannover. In those days theHouse of Hanover ruled theUnited Kingdom. The family name was eventually changed to Jordan (pronounced in the German manner,[ˈjɔʁdaːn]). A family tradition held that the first-born son in each generation be named Pascual.[3] Jordan was raised with a traditional religious upbringing. At age 12 he attempted to reconcile a literal interpretation of the Bible with Darwinian evolution; his teacher of religion convinced him there was no contradiction between science and religion (Jordan would write numerous articles on the relationship between the two throughout his life).[3]
Jordan enrolled in theTechnical University of Hannover in 1921 where he studiedzoology,mathematics, andphysics. As was typical for a German university student of the time, he shifted his studies to another university before obtaining a degree. TheUniversity of Göttingen, his destination in 1923, was then at the very zenith of its powers in mathematics and the physical sciences, such as under the guidance of mathematicianDavid Hilbert and the physicistArnold Sommerfeld. At Göttingen, Jordan became an assistant to the mathematicianRichard Courant for a time, and then he studied physics underMax Born and heredity under geneticist and race scientistAlfred Kühn[4] for his doctorate.
Jordan suffered aspeech impairment throughout his life, often stuttering badly[5] when giving unprepared remarks. In 1926,Niels Bohr offered to pay to treat it, and on the advice ofWilhelm Lenz, Jordan sought treatment atAlfred Adler's clinic in Vienna.[6][7]
Together withMax Born andWerner Heisenberg, Jordan was a coauthor of an important series of papers onquantum mechanics.[8] He went on to pioneer earlyquantum field theory[8] before largely switching his focus tocosmology before World War II.
Jordan devised a type ofnonassociative algebras, now namedJordan algebras, in an attempt to create an algebra of observables forquantum mechanics andquantum field theory. While the algebras proved not to be useful for that purpose, they have since found numerous applications within mathematics.[9] Jordan algebras have been applied inprojective geometry,number theory,complex analysis,optimization, and many other fields of pure and applied mathematics.
In 1966, Jordan published his 182-page workDie Expansion der Erde. Folgerungen aus der Diracschen Gravitationshypothese (The expansion of the Earth. Conclusions from the Dirac gravitation hypothesis)[10] in which he developed his theory that, according toPaul Dirac's hypothesis of a steady weakening ofgravitation throughout the history of the universe, theEarth may have swollen to its current size, from an initial ball of a diameter of only about 7,000 kilometres (4,300 mi). This theory could explain why theductile lowersima layer of theEarth's crust is of a comparatively uniform thickness, while the brittle uppersial layer of the Earth's crust had broken apart into the maincontinental plates. The continents having to adapt to the ever flatter surface of the growing ball, the mountain ranges on the Earth's surface would, in the course of that, have come into being as constricted folds.[11] Despite the energy Jordan invested in the expanding Earth theory, his geological work was never taken seriously by either physicists or geologists.[12]
Germany's defeat in theFirst World War and theTreaty of Versailles had a profound effect on Jordan's political beliefs. While many of his colleagues believed the Treaty to be unjust, Jordan went much further and became increasingly nationalistic and right-wing. He wrote numerous articles in the late 1920s that propounded an aggressive and bellicose stance. He was an anti-communist and was particularly concerned about the Russian Revolution and the rise of the Bolsheviks.[3] He wrote articles in several far-right journals under the pseudonymErnst Domeier, as was revealed in the 1990s.[9]
In 1933, Jordan joined theNazi party, likePhilipp Lenard andJohannes Stark, and, moreover, joined anSA unit. He supported the Nazis' nationalism and anti-communism but at the same time, he remained "a defender of Einstein" and other Jewish scientists. Jordan seemed to hope that he could influence the new regime; one of his projects was attempting to convince the Nazis that modern physics developed as represented by Einstein and especially the new Copenhagen brand of quantum theory could be the antidote to the "materialism of the Bolsheviks". However, while the Nazis appreciated his support for them, his continued support for Jewish scientists and their theories led him to be regarded as politically unreliable.[13][14]
Jordan enlisted in theLuftwaffe in 1939 and worked as a weather analyst at thePeenemünde rocket center, for a while. During the war he attempted to interest the Nazi party in various schemes for advanced weapons. His suggestions were ignored because he was considered "politically unreliable", probably because of his past associations with Jews (in particular: Born,Richard Courant andWolfgang Pauli) and the so-called "Jewish physics". Responding toLudwig Bieberbach, Jordan wrote: "The differences among German and French mathematics are not any more essential than the differences between German and French machine guns."[3]
Immediately after the war, Jordan wrote a letter to Bohr to "give a short coherent account of what I did during these black 12 years", painting emigration as impractical due to his mother's ill health and his speech impediment, before outlining the difficulties he faced as a high-profile student of emigré teachers. As an example of his work pushing back against Nazi ideology, he claimed that his bookPhysics of the Twentieth Century was an "attack" onRosenberg'sMyth of the twentieth century that risked landing him in the crosshairs of the SS. He went on to draw a sharp distinction betweenGerman militarism and Nazism proper, citing theJuly 20 plot as evidence.[15]
Had Jordan not joined the Nazi party, it is conceivable that he could have won aNobel Prize in Physics for his work with Max Born. Born would go on to win the 1954 Physics Prize withWalther Bothe.[16][17]
Wolfgang Pauli declared Jordan to be "rehabilitated" to theWest German authorities some time after the war, allowing him to regain academic employment after a two-year period. In 1953 he recovered his full status as a tenured professor, at theUniversity of Hamburg, where he stayed until he became emeritus in 1971.
Jordan went against Pauli's advice, and reentered politics after the period ofdenazification came to an end under the pressures of theCold War. In 1957 he secured election to theBundestag standing with theconservativeChristian Democratic Union. In 1957 Jordan supported the arming of theBundeswehr withtactical nuclear weapons by theAdenauer government, while theGöttingen Eighteen (a group of German physicists which included Born and Heisenberg) issued theGöttinger Manifest in protest. This and other issues were to further strain his relationships with his former friends and colleagues.[3]
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