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Wednesday, September 3, 2014

Werner Heisenberg

Werner Heisenberg

From Wikipedia, the free encyclopedia
Werner Heisenberg
Bundesarchiv Bild183-R57262, Werner Heisenberg.jpg
Heisenberg in 1933 (aged 32), as professor at Leipzig University
Born Werner Karl Heisenberg
5 December 1901
Würzburg, Bavaria, German Empire
Died 1 February 1976 (aged 74)
Munich, Bavaria, West Germany
Resting place Munich Waldfriedhof
Nationality German
Fields Theoretical Physics
Institutions University of Göttingen
University of Copenhagen
University of Leipzig
University of Berlin
University of Munich
Alma mater University of Munich
Doctoral advisor Arnold Sommerfeld
Other academic advisors Niels Bohr
Max Born
Doctoral students Felix Bloch
Edward Teller
Rudolf E. Peierls
Reinhard Oehme
Friedwardt Winterberg
Peter Mittelstaedt
Șerban Țițeica
Ivan Supek
Erich Bagge
Hermann Arthur Jahn
Raziuddin Siddiqui
Heimo Dolch
Hans Heinrich Euler
Edwin Gora
Bernhard Kockel
Arnold Siegert
Wang Foh-san
Karl Ott
Other notable students William Vermillion Houston
Guido Beck
Ugo Fano
Known for
Influenced Robert Döpel
Carl Friedrich von Weizsäcker
Notable awards Nobel Prize in Physics (1932)
Max Planck Medal (1933)
Spouse Elisabeth Schumacher (1937–1976)
Signature

Werner Karl Heisenberg (5 December 1901 – 1 February 1976) was a German theoretical physicist and one of the key creators of quantum mechanics. He published his work in 1925 in a breakthrough paper. In the subsequent series of papers with Max Born and Pascual Jordan, during the same year, this matrix formulation of quantum mechanics was substantially elaborated. In 1927 he published his uncertainty principle, upon which he built his philosophy and for which he is best known. Heisenberg was awarded the Nobel Prize in Physics for 1932 "for the creation of quantum mechanics".[1] He also made important contributions to the theories of the hydrodynamics of turbulent flows, the atomic nucleus, ferromagnetism, cosmic rays, and subatomic particles, and he was instrumental in planning the first West German nuclear reactor at Karlsruhe, together with a research reactor in Munich, in 1957. Considerable controversy surrounds his work on atomic research during World War II.

Following World War II, he was appointed director of the Kaiser Wilhelm Institute for Physics, which soon thereafter was renamed the Max Planck Institute for Physics. He was director of the institute until it was moved to Munich in 1958, when it was expanded and renamed the Max Planck Institute for Physics and Astrophysics.

Heisenberg was also president of the German Research Council, chairman of the Commission for Atomic Physics, chairman of the Nuclear Physics Working Group, and president of the Alexander von Humboldt Foundation.

Life and career

Early years

Heisenberg was born in Würzburg, Germany, to Kaspar Earnesta August Heisenberg, a secondary school teacher of classical languages who became Germany's only ordentlicher Professor (ordinarius professor) of medieval and modern Greek studies in the university system, and his wife, Annie Wecklein.[2]

Heisenberg, Habilitation 1924

He studied physics and mathematics from 1920 to 1923 at the Ludwig-Maximilians-Universität München and the Georg-August-Universität Göttingen. At Munich, he studied under Arnold Sommerfeld and Wilhelm Wien. At Göttingen, he studied physics with Max Born and James Franck, and he studied mathematics with David Hilbert. He received his doctorate in 1923, at Munich under Sommerfeld. He completed his Habilitation in 1924, at Göttingen under Born.[3][4]

Because Sommerfeld had a sincere interest in his students and knew of Heisenberg's interest in Niels Bohr's theories on atomic physics, Sommerfeld took Heisenberg to Göttingen to the Bohr-Festspiele (Bohr Festival) in June 1922. At the event, Bohr was a guest lecturer and gave a series of comprehensive lectures on quantum atomic physics. There, Heisenberg met Bohr for the first time, and it had a significant and continuing effect on him.[5][6][7]

Heisenberg's doctoral thesis, the topic of which was suggested by Sommerfeld, was on turbulence;[8] the thesis discussed both the stability of laminar flow and the nature of turbulent flow. The problem of stability was investigated by the use of the Orr–Sommerfeld equation, a fourth order linear differential equation for small disturbances from laminar flow. He briefly returned to this topic after World War II.[9]

Heisenberg's paper on the anomalous Zeeman effect[10] was accepted as his Habilitationsschrift (Habilitation thesis) under Max Born at Göttingen.[11]

In his youth he was a member and Scoutleader of the Neupfadfinder, a German Scout association and part of the German Youth Movement.[12][13][14] In August 1923 Robert Honsell and Heisenberg organized a trip (Großfahrt) to Finland with a Scout group of this association from Munich.[15]

Career

Göttingen, Copenhagen, and Leipzig

From 1924 to 1927, Heisenberg was a Privatdozent at Göttingen. From 17 September 1924 to 1 May 1925, under an International Education Board Rockefeller Foundation fellowship, Heisenberg went to do research with Niels Bohr, director of the Institute of Theoretical Physics at the University of Copenhagen. His seminal paper, Über quantentheoretischer Umdeutung was published in September 1925.[16] He returned to Göttingen and with Max Born and Pascual Jordan, over a period of about six months, developed the matrix mechanics formulation of quantum mechanics. On 1 May 1926,
Heisenberg began his appointment as a university lecturer and assistant to Bohr in Copenhagen. It was in Copenhagen, in 1927, that Heisenberg developed his uncertainty principle, while working on the mathematical foundations of quantum mechanics. On 23 February, Heisenberg wrote a letter to fellow physicist Wolfgang Pauli, in which he first described his new principle.[17] In his paper[18] on the uncertainty principle, Heisenberg used the word "Ungenauigkeit" (imprecision).[3][19][20]

In 1927, Heisenberg was appointed ordentlicher Professor (ordinarius professor) of theoretical physics and head of the department of physics at the Universität Leipzig; he gave his inaugural lecture on 1 February 1928. In his first paper published from Leipzig,[21] Heisenberg used the Pauli exclusion principle to solve the mystery of ferromagnetism.[3][4][19][22]

In Heisenberg's tenure at Leipzig, the quality of doctoral students, post-graduate and research associates who studied and worked with Heisenberg there is attested to by the acclaim later earned by these people; at various times, they included: Erich Bagge, Felix Bloch, Ugo Fano, Siegfried Flügge, William Vermillion Houston, Friedrich Hund, Robert S. Mulliken, Rudolf Peierls, George Placzek, Isidor Isaac Rabi, Fritz Sauter, John C. Slater, Edward Teller, John Hasbrouck van Vleck, Victor Frederick Weisskopf, Carl Friedrich von Weizsäcker, Gregor Wentzel and Clarence Zener.[23]

In early 1929, Heisenberg and Pauli submitted the first of two papers[24] laying the foundation for relativistic quantum field theory. Also in 1929, Heisenberg went on a lecture tour in China, Japan, India, and the United States.[19][23]

Shortly after the discovery of the neutron by James Chadwick in 1932, Heisenberg submitted the first of three papers[25] on his neutron-proton model of the nucleus. He was awarded the 1932 Nobel Prize in Physics.[19][26]

In 1928, the British mathematical physicist P. A. M. Dirac had derived the relativistic wave equation of quantum mechanics, which implied the existence of positive electrons, later to be named positrons. In 1932, from a cloud chamber photograph of cosmic rays, the American physicist Carl David Anderson identified a track as having been made by a positron. In mid-1933, Heisenberg presented his theory of the positron. His thinking on Dirac's theory and further development of the theory were set forth in two papers. The first, Bemerkungen zur Diracschen Theorie des Positrons (Remarks on Dirac's theory of the positron) was published in 1934,[27] and the second, Folgerungen aus der Diracschen Theorie des Positrons (Consequences of Dirac's Theory of the Positron), was published in 1936.[19][28][29] In these papers Heisenberg was the first to reinterpret the Dirac equation as a "classical" field equation for any point particle of spin ħ/2, itself subject to quantization conditions involving anti-commutators. Thus reinterpreting it as a (quantum) field equation accurately describing electrons, Heisenberg put matter on the same footing as electromagnetism: as being described by relativistic quantum field equations which allowed the possibility of particle creation and destruction. (Hermann Weyl had already described this in a 1929 letter to Einstein.)

In the early 1930s in Germany, the deutsche Physik movement was anti-Semitic and anti-theoretical physics, especially including quantum mechanics and the theory of relativity. As applied in the university environment, political factors took priority over the historically applied concept of scholarly ability,[30] even though its two most prominent supporters were the Nobel Laureates in Physics Philipp Lenard[31] and Johannes Stark.[32]

After Adolf Hitler came to power in 1933, Heisenberg was attacked in the press as a "White Jew"[33] by elements of the deutsche Physik (German Physics) movement for his insistence on teaching about the roles of Jewish scientists. As a result, he came under investigation by the SS. This was over an attempt to appoint Heisenberg as successor to Arnold Sommerfeld at the University of Munich. The issue was resolved in 1938 by Heinrich Himmler, head of the SS. While Heisenberg was not chosen as Sommerfeld's successor, he was rehabilitated to the physics community during the Third Reich. Nevertheless, supporters of deutsche Physik launched vicious attacks against leading theoretical physicists, including Arnold Sommerfeld and Heisenberg. On 29 June 1936, a National Socialist Party newspaper published a column attacking Heisenberg. On 15 July 1937, he was attacked in a journal of the SS. This was the beginning of what is called the Heisenberg Affair.[19]

In mid-1936, Heisenberg presented his theory of cosmic-ray showers in two papers.[34] Four more papers[35][36][37][38] appeared in the next two years.[19][39]

In June 1939, Heisenberg bought a summer home for his family in Urfeld, in southern Germany. He also traveled to the United States in June and July, visiting Samuel Abraham Goudsmit, at the University of Michigan in Ann Arbor. However, Heisenberg refused an invitation to emigrate to the United States. He did not see Goudsmit again until six years later, when Goudsmit was the chief scientific advisor to the American Operation Alsos at the close of World War II. Ironically, Heisenberg was arrested under Operation Alsos and detained in England under Operation Epsilon.[19][40][41]

Matrix mechanics and the Nobel Prize


Niels Bohr, Werner Heisenberg, and Wolfgang Pauli, ca. 1935

Heisenberg’s paper establishing quantum mechanics[42] has puzzled physicists and historians. His methods assume that the reader is familiar with Kramers-Heisenberg transition probability calculations. The main new idea, noncommuting matrices, is justified only by a rejection of unobservable quantities. It introduces the non-commutative multiplication of matrices by physical reasoning, based on the correspondence principle, despite the fact that Heisenberg was not then familiar with the mathematical theory of matrices. The path leading to these results has been reconstructed in MacKinnon, 1977,[43] and the detailed calculations are worked out in Aitchison et al.[44]

In Copenhagen, Heisenberg and Hans Kramers collaborated on a paper on dispersion, or the scattering from atoms of radiation whose wavelength is larger than the atoms. They showed that the successful formula Kramers had developed earlier could not be based on Bohr orbits, because the transition frequencies are based on level spacings which are not constant. The frequencies which occur in the Fourier transform of sharp classical orbits, by contrast, are equally spaced. But these results could be explained by a semi-classical Virtual State model: the incoming radiation excites the valence, or outer, electron to a virtual state from which it decays. In a subsequent paper Heisenberg showed that this virtual oscillator model could also explain the polarization of fluorescent radiation.

These two successes, and the continuing failure of the Bohr-Sommerfeld model to explain the outstanding problem of the anomalous Zeeman effect, led Heisenberg to use the virtual oscillator model to try to calculate spectral frequencies. The method proved too difficult to immediately apply to realistic problems, so Heisenberg turned to a simpler example, the anharmonic oscillator.

The dipole oscillator consists of a simple harmonic oscillator, which is thought of as a charged particle on a spring, perturbed by an external force, like an external charge. The motion of the oscillating charge can be expressed as a Fourier series in the frequency of the oscillator. Heisenberg solved for the quantum behavior by two different methods. First, he treated the system with the virtual oscillator method, calculating the transitions between the levels that would be produced by the external source.

He then solved the same problem by treating the anharmonic potential term as a perturbation to the harmonic oscillator and using the perturbation methods that he and Born had developed. Both methods led to the same results for the first and the very complicated second order correction terms. This suggested that behind the very complicated calculations lay a consistent scheme.

So Heisenberg set out to formulate these results without any explicit dependence on the virtual oscillator model. To do this, he replaced the Fourier expansions for the spatial coordinates by matrices, matrices which corresponded to the transition coefficients in the virtual oscillator method. He justified this replacement by an appeal to Bohr’s correspondence principle and the Pauli doctrine that quantum mechanics must be limited to observables.

On 9 July, Heisenberg gave Born this paper to review and submit for publication. When Born read the paper, he recognized the formulation as one which could be transcribed and extended to the systematic language of matrices,[45] which he had learned from his study under Jakob Rosanes[46] at Breslau University. Born, with the help of his assistant and former student Pascual Jordan, began immediately to make the transcription and extension, and they submitted their results for publication; the paper was received for publication just 60 days after Heisenberg's paper.[47] A follow-on paper was submitted for publication before the end of the year by all three authors.[48] (A brief review of Born's role in the development of the matrix mechanics formulation of quantum mechanics along with a discussion of the key formula involving the non-commutivity of the probability amplitudes can be found in an article by Jeremy Bernstein, Max Born and the Quantum Theory.[49] A detailed historical and technical account can be found in Mehra and Rechenberg's book The Historical Development of Quantum Theory. Volume 3. The Formulation of Matrix Mechanics and Its Modifications 1925–1926.[50])

Up until this time, matrices were seldom used by physicists; they were considered to belong to the realm of pure mathematics. Gustav Mie had used them in a paper on electrodynamics in 1912 and Born had used them in his work on the lattices theory of crystals in 1921. While matrices were used in these cases, the algebra of matrices with their multiplication did not enter the picture as they did in the matrix formulation of quantum mechanics.[51]

Born had learned matrix algebra from Rosanes, as already noted, but Born had also learned Hilbert's theory of integral equations and quadratic forms for an infinite number of variables as was apparent from a citation by Born of Hilbert's work Grundzüge einer allgemeinen Theorie der Linearen Integralgleichungen published in 1912.[52][53] Jordan, too was well equipped for the task. For a number of years, he had been an assistant to Richard Courant at Göttingen in the preparation of Courant and David Hilbert's book Methoden der mathematischen Physik I, which was published in 1924.[54] This book, fortuitously, contained a great many of the mathematical tools necessary for the continued development of quantum mechanics. In 1926, John von Neumann became assistant to David Hilbert, and he coined the term Hilbert space to describe the algebra and analysis which were used in the development of quantum mechanics.[55][56]

In 1928, Albert Einstein nominated Heisenberg, Born, and Jordan for the Nobel Prize in Physics,[57] but it was not to be. The announcement of the Nobel Prize in Physics for 1932 was delayed until November 1933.[58] It was at that time that it was announced Heisenberg had won the Prize for 1932 "for the creation of quantum mechanics, the application of which has, inter alia, led to the discovery of the allotropic forms of hydrogen"[59][60] and Erwin Schrödinger and Paul Adrien Maurice Dirac shared the 1933 Prize "for the discovery of new productive forms of atomic theory".[60] One can rightly ask why Born was not awarded the Prize in 1932 along with Heisenberg – Bernstein gives some speculations on this matter. One of them is related to Jordan joining the Nazi Party on 1 May 1933 and becoming a Storm Trooper.[61] Hence, Jordan's Party affiliations and Jordan's links to Born may have affected Born's chance at the Prize at that time. Bernstein also notes that when Born won the Prize in 1954, Jordan was still alive, and the Prize was awarded for the statistical interpretation of quantum mechanics, attributable alone to Born.[62]

Heisenberg's reaction to Born for Heisenberg receiving the Prize for 1932 and to Born for Born receiving the Prize in 1954 are also instructive in evaluating whether Born should have shared the Prize with Heisenberg. On 25 November 1933, Born received a letter from Heisenberg in which he said he had been delayed in writing due to a "bad conscience" that he alone had received the Prize "for work done in Göttingen in collaboration – you, Jordan and I." Heisenberg went on to say that Born and Jordan's contribution to quantum mechanics cannot be changed by "a wrong decision from the outside."[63] In 1954, Heisenberg wrote an article honoring Max Planck for his insight in 1900. In the article, Heisenberg credited Born and Jordan for the final mathematical formulation of matrix mechanics and Heisenberg went on to stress how great their contributions were to quantum mechanics, which were not "adequately acknowledged in the public eye."[64]

The Deutsche Physik movement

On 1 April 1935, the eminent theoretical physicist Arnold Sommerfeld, Heisenberg's doctoral advisor at the University of Munich, achieved emeritus status. However, Sommerfeld stayed in his chair during the selection process for his successor, which took until 1 December 1939. The process was lengthy due to academic and political differences between the Munich Faculty's selection and that of the Reichserziehungsministerium (REM, Reich Education Ministry) and the supporters of Deutsche Physik, which was anti-Semitic and had a bias against theoretical physics, especially quantum mechanics and the theory of relativity.

In 1935, the Munich Faculty drew up a list of candidates to replace Sommerfeld as ordinarius professor of theoretical physics and head of the Institute for Theoretical Physics at the University of Munich. There were three names on the list: Werner Heisenberg, who received the Nobel Prize in Physics for 1932, Peter Debye, who received the Nobel Prize in Chemistry in 1936, and Richard Becker – all former students of Sommerfeld. The Munich Faculty was firmly behind these candidates, with Heisenberg as their first choice. However, supporters of Deutsche Physik and elements in the REM had their own list of candidates, and the battle dragged on for over four years. During this time, Heisenberg came under vicious attack by the Deutsche Physik supporters. One attack was published in Das Schwarze Korps, the newspaper of the Schutzstaffel (SS), headed by Heinrich Himmler. In this, Heisenberg was called a "White Jew" (i.e. an Aryan who acts like a Jew) who should be made to "disappear".[65] These attacks were taken seriously, as Jews were violently attacked and incarcerated. Heisenberg fought back with an editorial and a letter to Himmler, in an attempt to resolve this matter and regain his honour.

At one point, Heisenberg's mother visited Himmler's mother. The two women knew each other, as Heisenberg's maternal grandfather and Himmler's father were rectors and members of a Bavarian hiking club. Eventually, Himmler settled the Heisenberg affair by sending two letters, one to SS Gruppenführer Reinhard Heydrich and one to Heisenberg, both on 21 July 1938. In the letter to Heydrich, Himmler said Germany could not afford to lose or silence Heisenberg, as he would be useful for teaching a generation of scientists. To Heisenberg, Himmler said the letter came on recommendation of his family and he cautioned Heisenberg to make a distinction between professional physics research results and the personal and political attitudes of the involved scientists. The letter to Heisenberg was signed under the closing "Mit freundlichem Gruß und, Heil Hitler!" (With friendly greetings, Heil Hitler!")[66] Overall, the Heisenberg affair was a victory for academic standards and professionalism. However, the appointment of Wilhelm Müller to replace Sommerfeld was a political victory over academic standards. Müller was not a theoretical physicist, had not published in a physics journal, and was not a member of the Deutsche Physikalische Gesellschaft; his appointment was considered a travesty and detrimental to educating theoretical physicists.[66][67][68][69][70]

During the SS investigation of Heisenberg, the three investigators had training in physics. Heisenberg had participated in the doctoral examination of one of them at the Universität Leipzig. The most influential of the three, however, was Johannes Juilfs. During their investigation, they had become supporters of Heisenberg as well as his position against the ideological policies of the deutsche Physik movement in theoretical physics and academia.[71]

World War II

In 1939, shortly after the discovery of nuclear fission, the German nuclear energy project, also known as the Uranverein (Uranium Club), had begun. Heisenberg was one of the principal scientists leading research and development in the project.[citation needed]

From 15 to 22 September 1941, Heisenberg traveled to German-occupied Copenhagen to lecture and discuss nuclear research and theoretical physics with Niels Bohr. The meeting, and specifically what it might reveal about Heisenberg's intentions concerning developing nuclear weapons for the Nazi regime, is the subject of the award-winning Michael Frayn play titled Copenhagen. A television film version of the play was made by the BBC in 2002, with Stephen Rea as Bohr, and Daniel Craig as Heisenberg. The same meeting had previously been dramatised by the BBC's Horizon science documentary series in 1992, with Anthony Bate as Bohr, and Philip Anthony as Heisenberg.[72] Documents relating to the Bohr-Heisenberg meeting were released in 2002 by the Niels Bohr Archive and by the Heisenberg family.[73][74]

On 26 February 1942, Heisenberg presented a lecture to Reich officials on energy acquisition from nuclear fission, after the Army withdrew most of its funding.[75] The Uranium Club was transferred to the Reich Research Council (RFR) in July 1942. On 4 June 1942, Heisenberg was summoned to report to Albert Speer, Germany's Minister of Armaments, on the prospects for converting the Uranium Club's research toward developing nuclear weapons. During the meeting, Heisenberg told Speer that a bomb could not be built before 1945, and would require significant monetary and manpower resources.[76][77] Five days later, on 9 June 1942, Adolf Hitler issued a decree for the reorganization of the RFR as a separate legal entity under the Reich Ministry for Armament and Ammunition; the decree appointed Reich Marshall Hermann Göring as the president.[78]

In September 1942, Heisenberg submitted his first paper of a three-part series on the scattering matrix, or S-matrix, in elementary particle physics. The first two papers were published in 1943[79][80] and the third in 1944.[81] The S-matrix described only observables, i.e., the states of incident particles in a collision process, the states of those emerging from the collision, and stable bound states; there would be no reference to the intervening states. This was the same precedent as he followed in 1925 in what turned out to be the foundation of the matrix formulation of quantum mechanics through only the use of observables.[19][39]

In February 1943, Heisenberg was appointed to the Chair for Theoretical Physics at the Friedrich-Wilhelms-Universität (today, the Humboldt-Universität zu Berlin). In April, his election to the Preußische Akademie der Wissenschaften (Prussian Academy of Sciences) was approved. That same month, he moved his family to their retreat in Urfeld as Allied bombing increased in Berlin. In the summer, he dispatched the first of his staff at the Kaiser-Wilhelm Institut für Physik to Hechingen and its neighboring town of Haigerloch, on the edge of the Black Forest, for the same reasons. From 18–26 October, he traveled to German-occupied Netherlands. In December 1943, Heisenberg visited German-occupied Poland.[19][82]

From 24 January to 4 February 1944, Heisenberg traveled to occupied Copenhagen, after the German Army confiscated Bohr's Institute of Theoretical Physics. He made a short return trip in April. In December, Heisenberg lectured in neutral Switzerland.[19] The United States Office of Strategic Services sent former major league baseball catcher and OSS agent Moe Berg to attend the lecture carrying a pistol, with orders to shoot Heisenberg if his lecture indicated that Germany was close to completing an atomic bomb. Heisenberg did not give such an indication, so Berg decided not to shoot him, a decision Berg later described as his own "uncertainty principle".[83]

In January 1945, Heisenberg, with most of the rest of his staff, moved from the Kaiser-Wilhelm Institut für Physik to the facilities in the Black Forest.[19]

Uranium Club

In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to Naturwissenschaften reporting they had detected the element barium after bombarding uranium with neutrons;[84] simultaneously, they communicated these results to Lise Meitner, who had in July of that year fled to the Netherlands and then went to Sweden.[85]

Meitner, and her nephew Otto Robert Frisch, correctly interpreted these results as being nuclear fission.[86] Frisch confirmed this experimentally on 13 January 1939.[87][88]

Paul Harteck was director of the physical chemistry department at the University of Hamburg and an advisor to the Heereswaffenamt (HWA, Army Ordnance Office). On 24 April 1939, along with his teaching assistant Wilhelm Groth, Harteck made contact with the Reichskriegsministerium (RKM, Reich Ministry of War) to alert them to the potential of military applications of nuclear chain reactions. Two days earlier, on 22 April 1939, after hearing a colloquium paper by Wilhelm Hanle on the use of uranium fission in a Uranmaschine (uranium machine, i.e., nuclear reactor), Georg Joos, along with Hanle, notified Wilhelm Dames, at the Reichserziehungsministerium (REM, Reich Ministry of Education), of potential military applications of nuclear energy. The communication was given to Abraham Esau, head of the physics section of the Reichsforschungsrat (RFR, Reich Research Council) at the REM. On 29 April, a group, organized by Esau, met at the REM to discuss the potential of a sustained nuclear chain reaction.

The group included the physicists Walther Bothe, Robert Döpel, Hans Geiger, Wolfgang Gentner (probably sent by Walther Bothe), Wilhelm Hanle, Gerhard Hoffmann and Georg Joos; Peter Debye was invited, but he did not attend. After this, informal work began at the Georg-August University of Göttingen by Joos, Hanle and their colleague Reinhold Mannfopff; the group of physicists was known informally as the first Uranverein (Uranium Club) and formally as Arbeitsgemeinschaft für Kernphysik. The group's work was discontinued in August 1939, when the three were called to military training.[89][90][91][92]

The second Uranverein began after the Heereswaffenamt (HWA, Army Ordnance Office) squeezed the Reichsforschungsrat (RFR, Reich Research Council) out of the Reichserziehungsministerium (REM, Reich Ministry of Education) and started the formal German nuclear energy project under military auspices. The second Uranverein was formed on 1 September 1939, the day World War II began, and it had its first meeting on 16 September 1939. The meeting was organized by Kurt Diebner, advisor to the HWA, and held in Berlin. The invitees included Walther Bothe, Siegfried Flügge, Hans Geiger, Otto Hahn, Paul Harteck, Gerhard Hoffmann, Josef Mattauch and Georg Stetter. A second meeting was held soon thereafter and included Klaus Clusius, Robert Döpel, Werner Heisenberg and Carl Friedrich von Weizsäcker. Also at this time, the Kaiser-Wilhelm Institut für Physik (KWIP, Kaiser Wilhelm Institute for Physics, after World War II the Max Planck Institute for Physics), in Berlin-Dahlem, was placed under HWA authority, with Diebner as the administrative director, and the military control of the nuclear research commenced.[91][92][93]

When it was apparent that the nuclear energy project would not make a decisive contribution to ending the war effort in the near term, control of the KWIP was returned in January 1942 to its umbrella organization, the Kaiser-Wilhelm Gesellschaft (KWG, Kaiser Wilhelm Society, after World War II the Max-Planck Gesellschaft), and HWA control of the project was relinquished to the RFR in July 1942. The nuclear energy project thereafter maintained its kriegswichtig (important for the war) designation and funding continued from the military. However, the German nuclear power project was then broken down into the following main areas: uranium and heavy water production, uranium isotope separation and the Uranmaschine (uranium machine, i.e., nuclear reactor). Also, the project was then essentially split up between a number of institutes, where the directors dominated the research and set their own research agendas.[91][94][95] The dominant personnel and facilities were the following:[96][97][98]
Heisenberg was appointed director-in-residence of the KWIP on 1 July 1942, as Peter Debye was still officially the director and on leave in the United States; Debye had gone on leave as he was a citizen of The Netherlands and had refused to become a German citizen when the HWA took administrative control of the KWIP. Heisenberg still also had his department of physics at the University of Leipzig where work was done for the Uranverein by Robert Döpel and his wife Klara Döpel. During the period Kurt Diebner administered the KWIP under the HWA program, considerable personal and professional animosity developed between Diebner and the Heisenberg inner circle – Heisenberg, Karl Wirtz, and Carl Friedrich von Weizsäcker.[19][99]

The point in 1942, when the army relinquished its control of the German nuclear energy project, was the zenith of the project relative to the number of personnel devoting time to the effort. There were only about 70 scientists working on the project, with about 40 devoting more than half their time to nuclear fission research. After this, the number of scientists working on applied nuclear fission diminished dramatically. Many of the scientists not working with the main institutes stopped working on nuclear fission and devoted their efforts to more pressing war related work.[100]

Over time, the HWA and then the RFR controlled the German nuclear energy project. The most influential people in the project were Kurt Diebner, Abraham Esau, Walther Gerlach and Erich Schumann. Schumann was one of the most powerful and influential physicists in Germany. Schumann was director of the Physics Department II at the Frederick William University (later, University of Berlin), which was commissioned and funded by the Oberkommando des Heeres (OKH, Army High Command) to conduct physics research projects. He was also head of the research department of the HWA, assistant secretary of the Science Department of the OKH and Bevollmächtiger (plenipotentiary) for high explosives. Diebner, throughout the life of the nuclear energy project, had more control over nuclear fission research than did Walther Bothe, Klaus Clusius, Otto Hahn, Paul Harteck or Werner Heisenberg.[101][102]

1945: Operation Alsos and Operation Epsilon

Operation Alsos was an Allied effort commanded by the Russian-American Colonel Boris T. Pash.
He reported directly to General Leslie Groves, commander of the Manhattan Engineer District, which was developing atomic weapons for the United States. The chief scientific advisor to Operation Alsos was the physicist Samuel Abraham Goudsmit. Goudsmit was selected for this task because of his knowledge of physics, he spoke German, and he personally knew a number of the German scientists working on the German nuclear energy project. He also knew little of the Manhattan Project, so, if he were captured, he would have little intelligence value to the Germans.

The objectives of Operation Alsos were to determine if the Germans had an atomic bomb program and to exploit German atomic related facilities, intellectual materials, materiel resources, and scientific personnel for the benefit of the US. Personnel on this operation generally swept into areas which had just come under control of the Allied military forces, but sometimes they operated in areas still under control by German forces.[103][104][105]

Berlin had been a location of many German scientific research facilities. To limit casualties and loss of equipment, many of these facilities were dispersed to other locations in the latter years of the war. The Kaiser-Wilhelm-Institut für Physik (KWIP, Kaiser Wilhelm Institute for Physics) had mostly been moved in 1943 and 1944 to Hechingen and its neighboring town of Haigerloch, on the edge of the Black Forest, which eventually became the French occupation zone. This move and a little luck allowed the Americans to take into custody a large number of German scientists associated with nuclear research. The only section of the institute which remained in Berlin was the low-temperature physics section, headed by Ludwig Bewilogua (1906–83), who was in charge of the exponential uranium pile.[106][107]

Nine of the prominent German scientists who published reports in Kernphysikalische Forschungsberichte as members of the Uranverein[108] were picked up by Operation Alsos and incarcerated in England under Operation Epsilon: Erich Bagge, Kurt Diebner, Walther Gerlach, Otto Hahn, Paul Harteck, Werner Heisenberg, Horst Korsching, Carl Friedrich von Weizsäcker and Karl Wirtz. Also, incarcerated was Max von Laue, although he had nothing to do with the nuclear energy project. Goudsmit, the chief scientific advisor to Operation Alsos, thought von Laue might be beneficial to the postwar rebuilding of Germany and would benefit from the high level contacts he would have in England.[109]

Heisenberg had been captured and arrested by Colonel Pash at Heisenberg's retreat in Urfeld, on 3 May 1945, in what was a true alpine-type operation in territory still under control by German forces. He was taken to Heidelberg, where, on 5 May, he met Goudsmit for the first time since the Ann Arbor visit in 1939. Germany surrendered just two days later. Heisenberg did not see his family again for eight months. Heisenberg was moved across France and Belgium and flown to England on 3 July 1945.[110][111][112]

The 10 German scientists were held at Farm Hall in England. The facility had been a safe house of the British foreign intelligence MI6. During their detention, their conversations were recorded. Conversations thought to be of intelligence value were transcribed and translated into English. The transcripts were released in 1992. Bernstein has published an annotated version of the transcripts in his book Hitler's Uranium Club: The Secret Recordings at Farm Hall, along with an introduction to put them in perspective. A complete, unedited publication of the British version of the reports appeared as Operation Epsilon: The Farm Hall Transcripts, which was published in 1993 by the Institute of Physics in Bristol and by the University of California Press in the US.[113][114][115]

Post 1945

On 3 January 1946, the 10 Operation Epsilon detainees were transported to Alswede in Germany, which was in the British occupation zone. Heisenberg settled in Göttingen, also in the British zone. In July, he was named director of the Kaiser-Wilhelm-Institut für Physik (KWIP, Kaiser Wilhelm Institute for Physics), then located in Göttingen. Shortly thereafter, it was renamed the Max-Planck-Institut für Physik, in honor of Max Planck and to assuage political objections to the continuation of the institute. Heisenberg was its director until 1958. In 1958, the institute was moved to Munich, expanded, and renamed Max-Planck-Institut für Physik und Astrophysik (MPIFA). Heisenberg was its director from 1960 to 1970; in the interim, Heisenberg and the astrophysicist Ludwig Biermann were co-directors. Heisenberg resigned his directorship of the MPIFA on 31 December 1970. Upon the move to Munich, Heisenberg also became an ordentlicher Professor (ordinarius professor) at the University of Munich.[4][19]

Just as the Americans did with Operation Alsos, the Soviets inserted special search teams into Germany and Austria in the wake of their troops. Their objective, under the Russian Alsos, was also the exploitation of German atomic related facilities, intellectual materials, materiel resources and scientific personnel for the benefit of the Soviet Union. One of the German scientists recruited under this Soviet operation was the nuclear physicist Heinz Pose, who was made head of Laboratory V in Obninsk. When he returned to Germany on a recruiting trip for his laboratory, Pose wrote a letter to Werner Heisenberg inviting him to work in the USSR. The letter lauded the working conditions in the USSR and the available resources, as well as the favorable attitude of the Soviets towards German scientists. A courier hand delivered the recruitment letter, dated 18 July 1946, to Heisenberg; Heisenberg politely declined in a return letter to Pose.[116][117]

In 1947, Heisenberg presented lectures in Cambridge, Edinburgh and Bristol. Heisenberg also contributed to the understanding of the phenomenon of superconductivity with a paper in 1947[118] and two papers in 1948,[119][120] one of them with Max von Laue.[19][121]

In the period shortly after World War II, Heisenberg briefly returned to the subject of his doctoral thesis, turbulence. Three papers were published in 1948[122][123][124] and one in 1950.[9][125]
In the post-war period, Heisenberg continued his interests in cosmic-ray showers with considerations on multiple production of mesons. He published three papers[126][127][128] in 1949, two[129][130] in 1952, and one[131] in 1955.[132]

On 9 March 1949, the Deutsche Forschungsrat (German Research Council) was established by the Max-Planck Gesellschaft (MPG, Max Planck Society, successor organization to the Kaiser-Wilhelm Gesellschaft). Heisenberg was appointed president of the Deutsche Forschungsrat. In 1951, the organization was fused with the Notgemeinschaft der Deutschen Wissenschaft (NG, Emergency Association of German Science) and that same year renamed the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). With the merger, Heisenberg was appointed to the presidium.[19][133][134]

In 1952, Heisenberg served as the chairman of the Commission for Atomic Physics of the DFG. Also that year, he headed the German delegation to the European Council for Nuclear Research.[3][19]
In 1953, Heisenberg was appointed president of the Alexander von Humboldt-Stiftung by Konrad Adenauer. Heisenberg served until 1975. Also, from 1953, Heisenberg's theoretical work concentrated on the unified field theory of elementary particles.[3][4][19]

In late 1955 to early 1956, Heisenberg gave the Gifford Lectures at St Andrews University, in Scotland, on the intellectual history of physics. The lectures were later published as Physics and Philosophy: The Revolution in Modern Science.[135]

During 1956 and 1957, Heisenberg was the chairman of the Arbeitskreis Kernphysik (Nuclear Physics Working Group) of the Fachkommission II "Forschung und Nachwuchs" (Commission II "Research and Growth") of the Deutschen Atomkommission (DAtK, German Atomic Energy Commission). Other members of the Nuclear Physics Working Group in both 1956 and 1957 were: Walther Bothe, Hans Kopfermann (vice-chairman), Fritz Bopp, Wolfgang Gentner, Otto Haxel, Willibald Jentschke, Heinz Maier-Liebnitz, Josef Mattauch, Wolfgang Riezler, Wilhelm Walcher and Carl Friedrich von Weizsäcker. Wolfgang Paul was also a member of the group during 1957.[136]

In 1957, Heisenberg was a signatory of the manifesto of the Göttinger Achtzehn (Göttingen Eighteen).[137]

From 1957, Heisenberg was interested in plasma physics and the process of nuclear fusion. He also collaborated with the International Institute of Atomic Physics in Geneva. He was a member of the Institute's Scientific Policy Committee, and for several years was the Committee's chairman.[3]

In 1973, Heisenberg gave a lecture at Harvard University on the historical development of the concepts of quantum theory.[138]

On 24 March 1973, Heisenberg gave a speech before the Catholic Academy of Bavaria, accepting the Romano Guardini Prize. An English translation of its title is "Scientific and Religious Truth." And its stated goal was "In what follows, then, we shall first of all deal with the unassailability and value of scientific truth, and then with the much wider field of religion, of which – so far as the Christian religion is concerned – Guardini himself has so persuasively written; finally – and this will be the hardest part to formulate – we shall speak of the relationship of the two truths."[139] A more detailed insight into Heisenberg's view on religion has been discussed by Wilfried Schröder in "Natural science and religion" (Bremen 1999, Science edition) and Wilfried Schröder "Naturerkenntnis und Religion" (Bremen, science edition 2008).

Personal life

In January 1937 Heisenberg met Elisabeth Schumacher (1914-1998) at a private music recital. Elisabeth was the daughter of a well-known Berlin economics professor, and her brother was the economist E. F. Schumacher, author of Small is Beautiful. Heisenberg married her on 29 April.
Fraternal twins Maria and Wolfgang were born in January 1938, whereupon Wolfgang Pauli congratulated Heisenberg on his "pair creation" – a word play on a process from elementary particle physics, pair production. They had five more children over the next 12 years: Barbara, Christine, Jochen, Martin and Verena. Jochen became a physics professor at the University of New Hampshire.[140][141]

Heisenberg enjoyed classical music and was an accomplished pianist.[3]

On his religious views, Heisenberg was raised and lived as a Lutheran Christian, publishing and giving several talks reconciling science with his faith.[142]

In his speech Scientific and Religious Truth (1974) while accepting the Romano Guardini Prize, Heisenberg affirmed:

“In the history of science, ever since the famous trial of Galileo, it has repeatedly been claimed that scientific truth cannot be reconciled with the religious interpretation of the world. Although I am now convinced that scientific truth is unassailable in its own field, I have never found it possible to dismiss the content of religious thinking as simply part of an outmoded phase in the consciousness of mankind, a part we shall have to give up from now on. Thus in the course of my life I have repeatedly been compelled to ponder on the relationship of these two regions of thought, for I have never been able to doubt the reality of that to which they point.” (Heisenberg 1974, 213)[143]

“Where no guiding ideals are left to point the way, the scale of values disappears and with it the meaning of our deeds and sufferings, and at the end can lie only negation and despair. Religion is therefore the foundation of ethics, and ethics the presupposition of life.” (Heisenberg 1974, 219).[144]

“The first gulp from the glass of natural sciences will turn you into an atheist, but at the bottom of the glass God is waiting for you.” -W.Heisenberg [145][146]

In his autobiographical article in the journal Truth, Henry Margenau (Professor Emeritus of Physics and Natural Philosophy at Yale University) pointed out: “I have said nothing about the years between 1936 and 1950. There were, however, a few experiences I cannot forget. One was my first meeting with Heisenberg, who came to America soon after the end of the Second World War. Our conversation was intimate and he impressed me by his deep religious conviction. He was a true Christian in every sense of that word.” [147]

Heisenberg also enjoyed mountaineering. In his autobiography, he included photographs from this activity.

Heisenberg died of cancer of the kidneys and gall bladder at his home, on 1 February 1976.[148] The next evening, his colleagues and friends walked in remembrance from the Institute of Physics to his home and each put a candle near the front door.[149] He is buried at Munich Waldfriedhof.

Honors and awards

Heisenberg was awarded a number of honors:[3]

Research Reports in Nuclear Physics

The following reports were published in Kernphysikalische Forschungsberichte (Research Reports in Nuclear Physics), an internal publication of the German Uranverein. The reports were classified Top Secret, they had very limited distribution, and the authors were not allowed to keep copies. The reports were confiscated under the Allied Operation Alsos and sent to the United States Atomic Energy Commission for evaluation. In 1971, the reports were declassified and returned to Germany.
The reports are available at the Karlsruhe Nuclear Research Center and the American Institute of Physics.[150][151]
  • Robert Döpel, K. Döpel, and Werner Heisenberg Bestimmung der Diffusionslänge thermischer Neutronen in Präparat 38[152] G-22 (5 December 1940)
  • Robert Döpel, K. Döpel, and Werner Heisenberg Bestimmung der Diffusionslänge thermischer Neutronen in schwerem Wasser G-23 (7 August 1940)
  • Werner Heisenberg Die Möglichkeit der technischer Energiegewinnung aus der Uranspaltung G-39 (6 December 1939)
  • Werner Heisenberg Bericht über die Möglichkeit technischer Energiegewinnung aus der Uranspaltung (II) G-40 (29 February 1940)
  • Robert Döpel, K. Döpel, and Werner Heisenberg Versuche mit Schichtenanordnungen von D2O und 38 G-75 (28 October 1941)
  • Werner Heisenberg Über die Möglichkeit der Energieerzeugung mit Hilfe des Isotops 238 G-92 (1941)
  • Werner Heisenberg Bericht über Versuche mit Schichtenanordnungen von Präparat 38 und Paraffin am Kaiser Wilhelm Institut für Physik in Berlin-Dahlem G-93 (May 1941)
  • Fritz Bopp, Erich Fischer, Werner Heisenberg, Carl-Friedrich von Weizsäcker, and Karl Wirtz Untersuchungen mit neuen Schichtenanordnungen aus U-metall und Paraffin G-127 (March 1942)
  • Robert Döpel Bericht über Unfälle beim Umgang mit Uranmetall G-135 (9 July 1942)
  • Werner Heisenberg Bemerkungen zu dem geplanten halbtechnischen Versuch mit 1,5 to D2O und 3 to 38-Metall G-161 (31 July 1942)
  • Werner Heisenberg, Fritz Bopp, Erich Fischer, Carl-Friedrich von Weizsäcker, and Karl Wirtz Messungen an Schichtenanordnungen aus 38-Metall und Paraffin G-162 (30 October 1942)
  • Robert Döpel, K. Döpel, and Werner Heisenberg Der experimentelle Nachweis der effektiven Neutronenvermehrung in einem Kugel-Schichten-System aus D2O und Uran-Metall G-136 (July 1942)
  • Werner Heisenberg Die Energiegewinnung aus der Atomkernspaltung G-217 (6 May 1943)
  • Fritz Bopp, Walther Bothe, Erich Fischer, Erwin Fünfer, Werner Heisenberg, O. Ritter, and Karl Wirtz Bericht über einen Versuch mit 1.5 to D2O und U und 40 cm Kohlerückstreumantel (B7) G-300 (3 January 1945)
  • Robert Döpel, K. Döpel, and Werner Heisenberg Die Neutronenvermehrung in einem D2O-38-Metallschichtensystem G-373 (March 1942)

Publications

Collected bibliographies
Selected articles

Books

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Alfred,Lord Tennyson : Ulysses

Alfred,Lord Tennyson : Ulysses


    It little profits that an idle king1,
    By this still hearth, among these barren crags,
    Matched with an agèd wife, I mete and dole
    Unequal laws unto a savage race,
    That hoard, and sleep, and feed, and know not me.

    I cannot rest from travel: I will drink
    Life to the lees: all times I have enjoyed
    Greatly, have suffered greatly, both with those
    That loved me, and alone; on shore, and when
    Through scudding drifts the rainy Hyades2
    Vexed the dim sea: I am become a name;
    For always roaming with a hungry heart
    Much have I seen and known; cities of men
    And manners, climates, councils, governments,
    Myself not least, but honoured of them all;
    And drunk delight of battle with my peers,
    Far on the ringing plains of windy Troy3.
    I am a part of all that I have met;
    Yet all experience is an arch wherethrough
    Gleams that untravelled world, whose margin fades
    For ever and for ever when I move.
    How dull it is to pause, to make an end,
    To rust unburnished, not to shine in use!
    As though to breathe were life. Life piled on life
    Were all too little, and of one to me
    Little remains: but every hour is saved
    From that eternal silence, something more,
    A bringer of new things; and vile it were
    For some three suns to store and hoard myself,
    And this grey spirit yearning in desire
    To follow knowledge like a sinking star,
    Beyond the utmost bound of human thought.

        This my son, mine own Telemachus,
    To whom I leave the sceptre and the isle—
    Well-loved of me, discerning to fulfil
    This labour, by slow prudence to make mild
    A rugged people, and through soft degrees
    Subdue them to the useful and the good.
    Most blameless is he, centred in the sphere
    Of common duties, decent not to fail
    In offices of tenderness, and pay
    Meet adoration to my household gods,
    When I am gone. He works his work, I mine.

        There lies the port; the vessel puffs her sail:
    There gloom the dark broad seas. My mariners,
    Souls that have toiled, and wrought, and thought
        with me—
    That ever with a frolic welcome took
    The thunder and the sunshine, and opposed
    Free hearts, free foreheads—you and I are old;
    Old age hath yet his honour and his toil;
    Death closes all: but something ere the end,
    Some work of noble note, may yet be done,
    Not unbecoming men that strove with Gods.
    The lights begin to twinkle from the rocks:
    The long day wanes: the slow moon climbs: the deep
    Moans round with many voices. Come, my friends,
    'Tis not too late to seek a newer world.
    Push off, and sitting well in order smite
    The sounding furrows; for my purpose holds
    To sail beyond the sunset, and the baths
    Of all the western stars, until I die.
    It may be that the gulfs will wash us down:
    It may be we shall touch the Happy Isles4,
    And see the great Achilles5, whom we knew
    Though much is taken, much abides; and though
    We are not now that strength which in old days
    Moved earth and heaven; that which we are, we are;
    One equal temper of heroic hearts,
    Made weak by time and fate, but strong in will
    To strive, to seek, to find, and not to yield.

Alfred,Lord Tennyson (1809-1892)    1833
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U.S. wind energy industry is doing quite well too (It’s not all about solar)

U.S. wind energy industry is doing quite well too (It’s not all about solar)


1
Aug 22, 2014

Original link:  http://www.smartgridnews.com/artman/publish/Technologies_DG_Renewables/U-S-wind-energy-industry-is-doing-quite-well-too-It-s-not-all-about-solar-6712.html/#.VAdaIWNdx5-
 
The U.S. wind energy industry generally gets overlooked as the solar industry grabs the biggest share of the spotlight in the renewables world. Solar is getting cheaper almost by the day. Many expect rooftop solar coupled with energy storage to be the next big thing, and the net metering debate continues.
 
But two new Energy Department reports say U.S. wind energy is quite healthy, thank you. DOE considers wind power to be a “key component” of the strategy to cut carbon pollution, diversify the  country’s energy economy and more. Scan the press release below for an overview and click on the links for more detail.
 
Energy Department Reports Highlight Strength of U.S. Wind Energy Industry
 
smart grid, modern grid, smart grid technology, renewable energy, wind power, U.S. wind power, Department of Energy







Washington, D.C. -- The U.S. continues to be a global leader in wind energy, ranking second in installed capacity in the world, according to two reports released today by the Department of Energy.
Wind power is a key component of the nation’s all-of-the-above strategy to reduce carbon pollution, diversify our energy economy, and bring innovative technologies on line. With increasing wind energy generation and decreasing prices of wind energy technologies, the U.S. wind energy market remains strong and the U.S. is moving closer to doubling renewable electricity generation from energy resources like wind power yet again by 2020.
 
“As a readily expandable, domestic source of clean, renewable energy, wind power is paving the way to a low-carbon future that protects our air and water while providing affordable, renewable electricity to American families and businesses,” said Energy Secretary Ernest Moniz. “However, the continued success of the U.S. wind industry highlights the importance of policies like the Production Tax Credit that provide a solid framework for America to lead the world in clean energy innovation while also keeping wind manufacturing and jobs in the U.S.”


Wind Technologies Market Report


After modest growth in 2013, total installed wind power capacity in the United States now stands at 61 gigawatts (GW), which meets nearly 4.5 percent of electricity demand in an average year, according to the 2013 Wind Technologies Market Report, released today by the Energy Department and its Lawrence Berkeley National Laboratory. The report also found that wind energy prices – particularly in the Interior region of the United States–are at an all-time low, with utilities selecting wind as a cost-saving option.

With utility-scale turbines installed in more than 39 states and territories, the success of the U.S. wind industry has had a ripple effect on the American economy, spurring more than $500 million in exports and supporting jobs related to development, siting, manufacturing, transportation and other industries.
 

Distributed Wind Market Report


In total, U.S. turbines in distributed applications, which accounted for more than 80 percent of all wind turbines installed in the U.S. last year, reached a cumulative installed capacity of more than 842 MW–enough to power 120,000 average American homes–according to the 2013 Distributed Wind Market Report, also released today by the Energy Department and its Pacific Northwest National Laboratory. This capacity is supplied by roughly 72,000 turbines across all 50 states, Puerto Rico, and the U.S. Virgin Islands. In fact, a total of 14 states, including Iowa, Nevada and California, among others, now each have more than 10 MW of distributed wind capacity.
 
Compared to traditional, centralized power plants, distributed wind energy installations supply power directly to the local grid near homes, farms, businesses and communities. Turbines used in these applications can range in size from a few hundred watts to multi-megawatts, and can help power remote, off-grid homes and farms as well as local schools and manufacturing facilities.
 
For more information on these two new reports – including infographics, video and updated interactive map – visit www.energy.gov/windreport.
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Chameleons and holograms: Dark energy hunt gets weird

Chameleons and holograms: Dark energy hunt gets weird

  • 03 September 2014 by Hal Hodson, Chicago
  • Original link:  http://www.newscientist.com/article/mg22329852.400-chameleons-and-holograms-dark-energy-hunt-gets-weird.html?utm_source=NSNS&utm_medium=SOC&utm_campaign=facebookgoogletwitter&cmpid=SOC|NSNS|2012-GLOBAL-facebookgoogletwitter#.VAdaA2Ndx58
Cosmologists have revealed intruiging new ways to probe the mystery of whether dark energy exists and how it might be accelerating the universe’s growth

A LIGHT in the darkness can come from unexpected places. Unusual experiments for probing dark energy seem set to revolutionise our understanding of this mysterious force.

In Chicago last week, the world's largest meeting of cosmologists debated two of the forces that could push the universe apart: inflation, the proposed period of exponential expansion that the universe went through immediately after the big bang; and dark energy, the present-day force thought to be responsible for pushing the cosmos outward at an ever increasing rate.

The announcement in March that gravitational waves had been seen should essentially prove that inflation happened. But the results are on ice. The BICEP2 telescope team, which did the work, may have underestimated the impact of galactic dust on the signal. If real, the pattern of the waves they saw in the cosmic microwave background – the earliest light emitted in the universe – is the fingerprint of the universe's rapid expansion.

Astronomers and cosmologists at the International Conference on Particle Physics and Cosmology (COSMO) duked it out over how their models for the universe would be affected in two futures: one in which the results hold, the other in which dust blows them away.

"Everyone wants BICEP2 to be right," Will Kinney of the University at Buffalo, New York, told a packed auditorium. "Because if it is, we are going to be doing incredibly precise physics on the inflationary model within the foreseeable future. And it's going to be really cool."


For now, physicists will have to wait. New data from the Planck satellite, which could clear up BICEP2's problems, is not due to be released until November, but rumours swirled at COSMO that at least one paper based on Planck data within BICEP2's field of view will be published any day.

In the calm before that storm, much of the attention is on dark energy, and some big steps have been made. Dark energy is a theoretical necessity, exerting a repulsive force that explains how the speed of our universe's expansion is accelerating. But we know almost nothing about it.

COSMO saw novel work for exploring dark energy in Earthly laboratories (see "Chameleon screen"), an experiment that could show that the expansion is a fundamental property of space-time itself (see "A quantum of space-time"), and new constraints on the most devastating model of dark energy, which would see our universe tear itself apart, atom for atom (see "Phantom menace").



"Everybody and their mother is constraining dark energy," says Dragan Huterer at the University of Michigan in Ann Arbor. "That's the name of the game: you're measuring the expansion history of the universe."

Chameleon screen

Many physicists think dark energy is shoving the universe apart by countering gravity. If that's true, why have experiments never seen it? One hypothesis is that the force adapts to its environment and is only active in a near vacuum, while the dense matter of the solar system "screens" it from view.

Now Clare Burrage at the University of Nottingham, UK, and her colleagues have begun work on a laboratory test to find these screened "chameleon" forces.

If dark energy's effects can be felt only across a space as empty as the universe, Burrage says, then the same effect may show up in a vacuum chamber containing only a small ball of stable material and a cloud of a mere 1000 atoms. The team plans to use a laser to move the atoms 1 millimetre across the chamber.

As they travel, the atoms will feel the gravitational pull of Earth as well as that of the confounding ball of material, and the experiment will measure which forces are affecting them. If the disguising force of the ball is acting on the atoms, they should take a slightly different path, which will be visible in their final quantum states.

The team has not yet done the experiment, but has requested a special laser from a quantum GPS system from the UK Ministry of Defence, which should arrive in the next few months.

Finding chameleon-like effects won't necessarily mean they've found dark energy, says Adrienne Erickcek of the University of North Carolina at Chapel Hill. But it will show that screening mechanisms are a plausible explanation for our failure to measure the effects of dark energy in the local universe.

"This is very exciting," Erickcek says. "I had always assumed that the chameleon force would be screened no matter what, but they showed really convincingly that it need not be. It's amazing."

A quantum of space-time

An experiment in a shed in the suburbs of Chicago could show that dark energy is simply an emergent property of space-time, much as fluid dynamics emerges from how water molecules interact.

The goal of the Holometer experiment is to find the fundamental units of space and time. These would be a hundred billion billion times smaller than a proton. Like matter and energy at the quantum scale, these bits of space-time would act more like waves than particles.

"The theory is that space is made of waves instead of points, that everything is a little jittery, and never sits still," says Craig Hogan at the University of Chicago, who runs the experiment. The Holometer is designed to measure this "jitter".

It directs two powerful laser beams through tubes 40 metres long. The lasers measure the positions of mirrors along their paths at two points in time. If space-time is smooth and shows no quantum behaviour, then the mirrors should remain perfectly still. But if both lasers measure an identical, small difference in the mirrors' position over time, after all other effects are ruled out, that could mean the mirrors are being jiggled by fluctuations in the fabric of space.

Taking this idea a step further, Hogan says the quantum states of space-time and matter could be entangled, so you can't measure one without affecting the other.

Our best current theories describe space-time in terms of geometry, and matter in terms of quantum fields, but struggle to unite the two. If the Holometer sees something, Hogan says, it could point to a way of unifying them. At the tiny scales at which the two properties are connected, the geometry of space-time alone should force the universe to expand.

Hogan told the COSMO meeting that initial results show that Holometer can measure quantum fluctuations, if they are there, and could collect enough data for an answer within a year.

Phantom menace

Most models of dark energy hold that the amount of it remains constant. But about 10 years ago, cosmologists realised that if the total density of dark energy is increasing, we could be headed for a nightmare scenario – the "big rip". As space-time expands faster and faster, matter will be torn apart, starting with galaxy clusters and ending with atomic nuclei. Cosmologists called it "phantom" energy.

To find out if this could be true, Dragan Huterer at the University of Michigan in Ann Arbor turned to type Ia supernovae. These stellar explosions are all of the same brightness, so they act as cosmic yardsticks for measuring distances. The first evidence that the universe's expansion is accelerating came from studies of type Ia supernovae in the late 1990s.

If supernovae accelerated away from each other more slowly in the past than they do now, then dark energy's density may be increasing and we could be in trouble. "If you even move a millimetre off the ledge, you fall into the abyss," Huterer says.

Huterer and colleague Daniel Shafer have compiled data from recent supernova surveys and found that, depending on which surveys you use, there could be slight evidence that the dark energy density has been increasing over the past 2 billion years, but it's not statistically significant yet (Physical Review D, doi.org/vf9).

Phantom energy is an underdog theory, but the consequences are so dramatic that it's worth testing, Huterer says. The weakness of the evidence is balanced by the fact that the implications are huge, he says. "We will have to completely revise even our current thinking of dark energy if phantom is really at work."
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Lepton

Lepton

From Wikipedia, the free encyclopedia

Lepton
Beta Negative Decay.svg
Leptons are involved in several processes such as beta decay.
Composition Elementary particle
Statistics Fermionic
Generation 1st, 2nd, 3rd
Interactions Electromagnetism, Gravitation, Weak
Symbol l
Antiparticle Antilepton (l)
Types 6 (electron, electron neutrino, muon, muon neutrino, tau, tau neutrino)
Electric charge +1 e, 0 e, −1 e
Color charge No
Spin 1⁄2

A lepton is an elementary, spin-1⁄2 particle that does not undergo strong interactions, but is subject to the Pauli exclusion principle.[1] The best known of all leptons is the electron, which governs nearly all of chemistry as it is found in atoms and is directly tied to all chemical properties. Two main classes of leptons exist: charged leptons (also known as the electron-like leptons), and neutral leptons (better known as neutrinos). Charged leptons can combine with other particles to form various composite particles such as atoms and positronium, while neutrinos rarely interact with anything, and are consequently rarely observed.

There are six types of leptons, known as flavours, forming three generations.[2] The first generation is the electronic leptons, comprising the electron (e−) and electron neutrino (ν
e); the second is the muonic leptons, comprising the muon (μ−) and muon neutrino (ν
μ); and the third is the tauonic leptons, comprising the tau (τ−) and the tau neutrino (ν
τ). Electrons have the least mass of all the charged leptons. The heavier muons and taus will rapidly change into electrons through a process of particle decay: the transformation from a higher mass state to a lower mass state. Thus electrons are stable and the most common charged lepton in the universe, whereas muons and taus can only be produced in high energy collisions (such as those involving cosmic rays and those carried out in particle accelerators).

Leptons have various intrinsic properties, including electric charge, spin, and mass. Unlike quarks however, leptons are not subject to the strong interaction, but they are subject to the other three fundamental interactions: gravitation, electromagnetism (excluding neutrinos, which are electrically neutral), and the weak interaction. For every lepton flavor there is a corresponding type of antiparticle, known as antilepton, that differs from the lepton only in that some of its properties have equal magnitude but opposite sign. However, according to certain theories, neutrinos may be their own antiparticle, but it is not currently known whether this is the case or not.

The first charged lepton, the electron, was theorized in the mid-19th century by several scientists[3][4][5] and was discovered in 1897 by J. J. Thomson.[6] The next lepton to be observed was the muon, discovered by Carl D. Anderson in 1936, but it was erroneously classified as a meson at the time.[7] After investigation, it was realized that the muon did not have the expected properties of a meson, but rather behaved like an electron, only with higher mass. It took until 1947 for the concept of "leptons" as a family of particle to be proposed.[8] The first neutrino, the electron neutrino, was proposed by Wolfgang Pauli in 1930 to explain certain characteristics of beta decay.[8] It was first observed in the Cowan–Reines neutrino experiment conducted by Clyde Cowan and Frederick Reines in 1956.[8][9] The muon neutrino was discovered in 1962 by Leon M. Lederman, Melvin Schwartz and Jack Steinberger,[10] and the tau discovered between 1974 and 1977 by Martin Lewis Perl and his colleagues from the Stanford Linear Accelerator Center and Lawrence Berkeley National Laboratory.[11] The tau neutrino remained elusive until July 2000, when the DONUT collaboration from Fermilab announced its discovery.[12][13]

Leptons are an important part of the Standard Model. Electrons are one of the components of atoms, alongside protons and neutrons. Exotic atoms with muons and taus instead of electrons can also be synthesized, as well as lepton–antilepton particles such as positronium.

Etymology

The name lepton comes from the Greek λεπτόν (leptón), neuter of λεπτός (leptós), "fine, small, thin";[14] the earliest attested form of the word is the Mycenaean Greek 𐀩𐀡𐀵, re-po-to, written in Linear B syllabic script.[15] Lepton was first used by physicist Léon Rosenfeld in 1948:[16]
Following a suggestion of Prof. C. Møller, I adopt — as a pendant to "nucleon" — the denomination "lepton" (from λεπτός, small, thin, delicate) to denote a particle of small mass.
The etymology incorrectly implies that all the leptons are of small mass. When Rosenfeld named them, the only known leptons were electrons and muons, which are in fact of small mass — the mass of an electron (0.511 MeV/c2)[17] and the mass of a muon (with a value of 105.7 MeV/c2)[18] are fractions of the mass of the "heavy" proton (938.3 MeV/c2).[19] However, the mass of the tau (discovered in the mid 1970s) (1777 MeV/c2)[20] is nearly twice that of the proton, and about 3,500 times that of the electron.

History

A muon transmutes into a muon neutrino by emitting a W− boson. The W− boson subsequently decays into an electron and an electron antineutrino.

The first lepton identified was the electron, discovered by J.J. Thomson and his team of British physicists in 1897.[21][22] Then in 1930 Wolfgang Pauli postulated the electron neutrino to preserve conservation of energy, conservation of momentum, and conservation of angular momentum in beta decay.[23] Pauli theorized that an undetected particle was carrying away the difference between the energy, momentum, and angular momentum of the initial and observed final particles. The electron neutrino was simply called the neutrino, as it was not yet known that neutrinos came in different flavours (or different "generations").

Nearly 40 years after the discovery of the electron, the muon was discovered by Carl D. Anderson in 1936. Due to its mass, it was initially categorized as a meson rather than a lepton.[24] It later became clear that the muon was much more similar to the electron than to mesons, as muons do not undergo the strong interaction, and thus the muon was reclassified: electrons, muons, and the (electron) neutrino were grouped into a new group of particles – the leptons. In 1962 Leon M. Lederman, Melvin Schwartz and Jack Steinberger showed that more than one type of neutrino exists by first detecting interactions of the muon neutrino, which earned them the 1988 Nobel Prize, although by then the different flavours of neutrino had already been theorized.[25]

The tau was first detected in a series of experiments between 1974 and 1977 by Martin Lewis Perl with his colleagues at the SLAC LBL group.[26] Like the electron and the muon, it too was expected to have an associated neutrino. The first evidence for tau neutrinos came from the observation of "missing" energy and momentum in tau decay, analogous to the "missing" energy and momentum in beta decay leading to the discovery of the electron neutrino. The first detection of tau neutrino interactions was announced in 2000 by the DONUT collaboration at Fermilab, making it the latest particle of the Standard Model to have been directly observed,[27] apart from the Higgs boson, which probably has been discovered in 2012.

Although all present data is consistent with three generations of leptons, some particle physicists are searching for a fourth generation. The current lower limit on the mass of such a fourth charged lepton is 100.8 GeV/c2,[28] while its associated neutrino would have a mass of at least 45.0 GeV/c2.[29]

Properties

Spin and chirality

Left-handed and right-handed helicities

Leptons are spin-1⁄2 particles. The spin-statistics theorem thus implies that they are fermions and thus that they are subject to the Pauli exclusion principle; no two leptons of the same species can be in exactly the same state at the same time. Furthermore, it means that a lepton can have only two possible spin states, namely up or down.

A closely related property is chirality, which in turn is closely related to a more easily visualized property called helicity. The helicity of a particle is the direction of its spin relative to its momentum; particles with spin in the same direction as their momentum are called right-handed and otherwise they are called left-handed. When a particle is mass-less, the direction of its momentum relative to its spin is frame independent, while for massive particles it is possible to 'overtake' the particle by a Lorentz transformation flipping the helicity. Chirality is a technical property (defined through the transformation behaviour under the Poincaré group) that agrees with helicity for (approximately) massless particles and is still well defined for massive particles.

In many quantum field theories—such as quantum electrodynamics and quantum chromodynamics—left and right-handed fermions are identical. However in the Standard Model left-handed and right-handed fermions are treated asymmetrically. Only left-handed fermions participate in the weak interaction, while there are no right-handed neutrinos. This is an example of parity violation. In the literature left-handed fields are often denoted by a capital L subscript (e.g. e−L) and right-handed fields are denoted by a capital R subscript.

Electromagnetic interaction

Lepton-photon interaction

One of the most prominent properties of leptons is their electric charge, Q. The electric charge determines the strength of their electromagnetic interactions. It determines the strength of the electric field generated by the particle (see Coulomb's law) and how strongly the particle reacts to an external electric or magnetic field (see Lorentz force). Each generation contains one lepton with Q = −1 (conventionally the charge of a particle is expressed in units of the elementary charge) and one lepton with zero electric charge. The lepton with electric charge is commonly simply referred to as a 'charged positive lepton' while the neutral lepton is called a neutrino. For example the first generation consists of the electron e− with a negative electric charge and the electrically neutral electron neutrino ν
e.

In the language of quantum field theory the electromagnetic interaction of the charged leptons is expressed by the fact that the particles interact with the quantum of the electromagnetic field, the photon. The Feynman diagram of the electron-photon interaction is shown on the right.

Because leptons possess an intrinsic rotation in the form of their spin, charged leptons generate a magnetic field. The size of their magnetic dipole moment μ is given by,
\mu = g \frac{ Q e \hbar}{4 m},
where m is the mass of the lepton and g is the so-called g-factor for the lepton. First order approximation quantum mechanics predicts that the g-factor is 2 for all leptons. However, higher order quantum effects caused by loops in Feynman diagrams introduce corrections to this value.
These corrections, referred to as the anomalous magnetic dipole moment, are very sensitive to the details of a quantum field theory model and thus provide the opportunity for precision tests of the standard model. The theoretical and measured values for the electron anomalous magnetic dipole moment are within agreement within eight significant figures.[30]

Weak Interaction

Lepton-interaction-vertex-evW.svg Lepton-interaction-vertex-pvW.svg Lepton-interaction-vertex-eeZ.svg
The weak interactions of the first generation leptons.
In the Standard Model the left-handed charged lepton and the left-handed neutrino are arranged in doublet (ν
eL, e−L) that transforms in the spinor representation (T = 1⁄2) of the weak isospin SU(2) gauge symmetry. This means that these particles are eigenstates of the isospin projection T3 with eigenvalues 1⁄2 and −1⁄2 respectively. In the meantime, the right-handed charged lepton transforms as a weak isospin scalar (T = 0) and thus does not participate in the weak interaction, while there is no right-handed neutrino at all.

The Higgs mechanism recombines the gauge fields of the weak isospin SU(2) and the weak hypercharge U(1) symmetries to three massive vector bosons (W+, W−, Z0) mediating the weak interaction, and one massless vector boson, the photon, responsible for the electromagnetic interaction. The electric charge Q can be calculated from the isospin projection T3 and weak hypercharge YW through the Gell-Mann–Nishijima formula,
Q = T3 + YW/2
To recover the observed electric charges for all particles the left-handed weak isospin doublet (ν
eL, e−L) must thus have YW = −1, while the right-handed isospin scalar e−
R must have YW = −2. The interaction of the leptons with the massive weak interaction vector bosons is shown in the figure on the left.

Mass

In the Standard Model each lepton starts out with no intrinsic mass. The charged leptons (i.e. the electron, muon, and tau) obtain an effective mass through interaction with the Higgs field, but the neutrinos remain massless. For technical reasons the masslessness of the neutrinos implies that there is no mixing of the different generations of charged leptons as there is for quarks. This is in close agreement with current experimental observations.[31]

However, it is known from experiments – most prominently from observed neutrino oscillations[32] – that neutrinos do in fact have some very small mass, probably less than 2 eV/c2.[33] This implies the existence of physics beyond the Standard Model. The currently most favoured extension is the so-called seesaw mechanism, which would explain both why the left-handed neutrinos are so light compared to the corresponding charged leptons, and why we have not yet seen any right-handed neutrinos.

Leptonic numbers

The members of each generation's weak isospin doublet are assigned leptonic numbers that are conserved under the Standard Model.[34] Electrons and electron neutrinos have an electronic number of Le = 1, while muons and muon neutrinos have a muonic number of Lμ = 1, while tau particles and tau neutrinos have a tauonic number of Lτ = 1. The antileptons have their respective generation's leptonic numbers of −1.
Conservation of the leptonic numbers means that the number of leptons of the same type remains the same, when particles interact. This implies that leptons and antileptons must be created in pairs of a single generation. For example, the following processes are allowed under conservation of leptonic numbers:
Each generation forms a weak isospin doublet.
e− + e+ → γ + γ,
τ− + τ+ → Z0 + Z0,
but not these:
γ → e− + μ+,
W− → e− + ν
τ,
Z0 → μ− + τ+.

However, neutrino oscillations are known to violate the conservation of the individual leptonic numbers. Such a violation is considered to be smoking gun evidence for physics beyond the Standard Model. A much stronger conservation law is the conservation of the total number of leptons (L), conserved even in the case of neutrino oscillations, but even it is still violated by a tiny amount by the chiral anomaly.

Universality

The coupling of the leptons to gauge bosons are flavour-independent (i.e., the interactions between leptons and gauge bosons are the same for all leptons).[34] This property is called lepton universality and has been tested in measurements of the tau and muon lifetimes and of Z boson partial decay widths, particularly at the Stanford Linear Collider (SLC) and Large Electron-Positron Collider (LEP) experiments.[35]:241–243[36]:138

The decay rate (Γ) of muons through the process μ− → e− + ν
e + ν
μ is approximately given by an expression of the form (see muon decay for more details)[34]
\Gamma \left ( \mu^- \rarr e^- + \bar{\nu_e} +\nu_\mu \right ) = K_1G_F^2m_\mu^5,
where K1 is some constant, and GF is the Fermi coupling constant. The decay rate of tau particles through the process τ− → e− + ν
e + ν
τ is given by an expression of the same form[34]
\Gamma \left ( \tau^- \rarr e^- + \bar{\nu_e} +\nu_\tau \right ) = K_2G_F^2m_\tau^5,
where K2 is some constant. Muon–Tauon universality implies that K1 = K2. On the other hand, electron–muon universality implies[34]
\Gamma \left ( \tau^- \rarr e^- + \bar{\nu_e} +\nu_\tau \right ) = \Gamma \left ( \tau^- \rarr \mu^- + \bar{\nu_\mu} +\nu_\tau \right ).
This explains why the branching ratios for the electronic mode (17.85%) and muonic (17.36%) mode of tau decay are equal (within error).[20]

Universality also accounts for the ratio of muon and tau lifetimes. The lifetime of a lepton (τl) is related to the decay rate by[34]
\tau_l=\frac{B \left ( l^- \rarr e^- + \bar{\nu_e} +\nu_l \right )}{\Gamma \left ( l^- \rarr e^- + \bar{\nu_e} +\nu_l \right )},
where B(x → y) and Γ(x → y) denotes the branching ratios and the resonance width of the process x → y.

The ratio of tau and muon lifetime is thus given by[34]
\frac{\tau_\tau}{\tau_\mu} = \frac{B \left ( \tau^- \rarr e^- + \bar{\nu_e} +\nu_\tau \right )}{B \left ( \mu^- \rarr e^- + \bar{\nu_e} +\nu_\mu \right )}\left (\frac{m_\mu}{m_\tau}\right )^5.

Using the values of the 2008 Review of Particle Physics for the branching ratios of muons[18] and tau[20] yields a lifetime ratio of ~1.29×10−7, comparable to the measured lifetime ratio of ~1.32×10−7. The difference is due to K1 and K2 not actually being constants; they depend on the mass of leptons.

Table of leptons

Properties of leptons
Particle/Antiparticle Name Symbol Q (e) S Le Lμ Lτ Mass (MeV/c2) Lifetime (s) Common decay
Electron / Positron[17] e−/e+ −1/+1 1⁄2 +1/−1 0 0 0.510998910(13) Stable Stable
Muon / Antimuon[18] μ−/μ+ −1/+1 1⁄2 0 +1/−1 0 105.6583668(38) 2.197019(21)×10−6 e− + ν
e + ν
μ
Tau / Antitau[20] τ−/τ+ −1/+1 1⁄2 0 0 +1/−1 1776.84(17) 2.906(10)×10−13 See τ− decay modes
Electron neutrino / Electron antineutrino[33] ν
e/ν
e		 0 1⁄2 +1/−1 0 0 < 2.2×10−6[37] Unknown
Muon neutrino / Muon antineutrino[33] ν
μ/ν
μ		 0 1⁄2 0 +1/−1 0 < 0.17[37] Unknown
Tau neutrino / Tau antineutrino[33] ν
τ/ν
τ		 0 1⁄2 0 0 +1/−1 < 15.5[37] Unknown

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