21. Quantum Mechanics, 1925-1927: Triumph Of The Copenhagen Interpretation Part of exhibit on Werner Heisenberg and the uncertainty principle. http://www.aip.org/history/heisenberg/p09.htm

Heisenberg, standing front left, next to P.A.M. Dirac, in front of A.H. Compton, University of Chicago, 1929. We regard quantum mechanics as a complete theory for which the fundamental physical and mathematical hypotheses are no longer susceptible of modification. Heisenberg and Max Born, paper delivered to Solvay Congress of 1927 Niels Bohr's Institute for Theoretical Physics at the University of Copenhagen in the 1920s H eisenberg formulated the uncertainty principle in February 1927 while employed as a lecturer in Bohr's Institute for Theoretical Physics at the University of Copenhagen. Bohr, who had been on a skiing vacation, returned to the institute to find Heisenberg's paper already in draft. Forwarding the paper to Einstein at Heisenberg's request, Bohr complained to Einstein that Heisenberg's approach was too narrow and his gamma-ray microscope was flawed, although the result was correct. For Bohr, the uncertainty relations arose not merely from the quantum equations and the use of particles and discontinuity. Waves and particles had to be taken equally into account, and the scattering of light waves by the electron was also crucial. When Heisenberg corrected his thought experiment, it only confirmed the results. Niels Bohr, who articulated the Copenhagen interpretation of quantum mechanics and mentored a generation of quantum physicists

22. The Nobel Prize In Physics 1922 Nobelprize.org, The Official Web Site of the Nobel Prize http://nobelprize.org/nobel_prizes/physics/laureates/1922/

Home FAQ Press Contact Us ... Nobel Prize in Physics The Nobel Prize in Physics 1922 About the Nobel Prizes Facts and Lists Nobel Prize in Physics All Nobel Prizes in Physics ... Nobel Prize Award Ceremonies Sort and list Nobel Prizes and Nobel Laureates Create a List All Nobel Prizes Nobel Prize Awarded Organizations Women Nobel Laureates Nobel Laureates and Universities Prize category: Physics Chemistry Medicine Literature Peace Economics The Nobel Prize in Physics 1922 Niels Bohr The Nobel Prize in Physics 1922 Summary Presentation Speech Niels Bohr ... Other Resources Niels Henrik David Bohr The Nobel Prize in Physics 1922 was awarded to Niels Bohr "for his services in the investigation of the structure of atoms and of the radiation emanating from them" TO CITE THIS PAGE: MLA style: "The Nobel Prize in Physics 1922". Nobelprize.org. 1 Nov 2010 http://nobelprize.org/nobel_prizes/physics/laureates/1922/ About Nobelprize.org Technical Support Home FAQ ... Contact Us

23. Guide To Nobel Prize Early life. Bohr was the second of three children born into an upper middleclass Copenhagen family. His mother, Ellen (n e Adler), was the daughter of a prominent Jewish banker. http://www.britannica.com/nobelprize/article-280689

Home Nobel: The Man and the Prizes Britannica's Nobelists Nobelists by Prize ... Back To Britannica Bohr, Niels Early life Enrolling at the University of Copenhagen in 1903, Bohr was never in doubt that he would study physics. Research and teaching in this field took place in cramped quarters at the Polytechnic Institute, leased to the University for the purpose. Bohr obtained his doctorate in 1911 with a dissertation on the electron theory of metals. Aage N. Bohr , shared a third of the 1975 Nobel Prize for Physics in recognition of the collective model of the atomic nucleus proposed in the early 1950s. Back to top Previous Next Contents of this article: Introduction Early life Bohr atomic model Bohr's Institute for Theoretical Physics ... Additional Reading © 2010 Encyclopćdia Britannica, Inc.

24. The Nobel Prize In Physics 1922 For investigations of the structure of atoms and their radiation. Includes biography and presentation speech. http://nobelprize.org/physics/laureates/1922/

Home FAQ Press Contact Us ... Nobel Prize in Physics The Nobel Prize in Physics 1922 About the Nobel Prizes Facts and Lists Nobel Prize in Physics All Nobel Prizes in Physics ... Nobel Prize Award Ceremonies Sort and list Nobel Prizes and Nobel Laureates Create a List All Nobel Prizes Nobel Prize Awarded Organizations Women Nobel Laureates Nobel Laureates and Universities Prize category: Physics Chemistry Medicine Literature Peace Economics The Nobel Prize in Physics 1922 Niels Bohr The Nobel Prize in Physics 1922 Summary Presentation Speech Niels Bohr ... Other Resources Niels Henrik David Bohr The Nobel Prize in Physics 1922 was awarded to Niels Bohr "for his services in the investigation of the structure of atoms and of the radiation emanating from them" TO CITE THIS PAGE: MLA style: "The Nobel Prize in Physics 1922". Nobelprize.org. 1 Nov 2010 http://nobelprize.org/nobel_prizes/physics/laureates/1922/ About Nobelprize.org Technical Support Home FAQ ... Contact Us

25. Niels Bohr - Biography Of Niels Bohr Physics 101; History of Physics; Famous Physicists; Niels Bohr; Niels Bohr Biography of Niels Bohr http://physics.about.com/od/nielsbohr/p/bohr1.htm

zWASL=1;zGRH=1 zJs=10 zJs=11 zJs=12 zJs=13 zc(5,'jsc',zJs,9999999,'') zDO=0 Home Education Physics Physics Search Physics Basic Concepts Theories Experiments ... Share w(x2+zWl+'?p=1" zT="18/1[N" rel="nofollow">Print') Free Physics Newsletter! Sign Up Discuss in my Forum By Andrew Zimmerman Jones , About.com Guide See More About: niels bohr atomic model quantum physics famous physicists ... nobel prize A photograph of Niels Bohr Public Domain zSB(3,3) Basic Information: Fullname: Niels Henrik David Bohr Nationality: Danish Birth: Oct. 7, 1885 Death: Nov. 18, 1962 Spouse: Margrethe Norlund 1922 Nobel Prize for Physics: "for his services in the investigation of the structure of atoms and of the radiation emanating from them." Early Years: Bohr was born in Copenhagen, Denmark. He received a doctorate from Copenhagen University in 1911. In 1913, he developed the Bohr model of atomic structure, which introduced the theory of electrons orbiting around the atomic nucleus. His model involved the electrons being contained in quantized energy states so that when they drop from one state to another, energy is emitted. This work became central to quantum physics and it for this which he was awarded the 1922 Nobel Prize. Copenhagen: In 1916, Bohr became a professor at Copenhagen University. In 1920, he was appointed director of the new "Institute of Theoretical Physics." In this position, he was in a position to be instrumental in building the theoretical framework of quantum physics. The standard model of quantum physics throughout the first half of the century became known as the "Copenhagen interpretation," although several other interpretations now exist. Bohr's careful, thoughtful manner of approaching was colored with a playful personality, as clear in some famous

26. ESVA Bohr Mini-Exhibit Pictures from Emilio Segr Visual Archives. http://photos.aip.org/exhibits/bohr.jsp

27. Niels Bohr Niels Bohr. Niels Henrik David Bohr was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the http://www.crystalinks.com/bohr.html

Niels Bohr Niels Henrik David Bohr was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. Bohr mentored and collaborated with many of the top physicists of the century at his institute in Copenhagen. He was also part of the team of physicists working on the Manhattan Project. Bohr married Margrethe Nřrlund in 1912, and one of their sons, Aage Niels Bohr, grew up to be an important physicist who, like his father, received the Nobel prize, in 1975. Bohr has been described as one of the most influential physicists of the 20th century. Bohr was born in Copenhagen, Denmark in 1885. His father, Christian Bohr, a devout Lutheran, was professor of physiology at the University of Copenhagen (it is his name which is given to the Bohr shift or Bohr effect), while his mother, Ellen Adler Bohr, came from a wealthy Jewish family prominent in Danish banking and parliamentary circles. His brother was Harald Bohr, a mathematician and Olympic footballer who played on the Danish national team. Niels Bohr was a passionate footballer as well, and the two brothers played a number of matches for the Copenhagen-based Akademisk Boldklub. In 1903 Bohr enrolled as an undergraduate at Copenhagen University, initially studying philosophy and mathematics. In 1905, prompted by a gold medal competition sponsored by the Danish Academy of Sciences and Letters, he conducted a series of experiments to examine the properties of surface tension, using his father's laboratory in the university, familiar to him from assisting there since childhood. His essay won the prize, and it was this success that decided Bohr to abandon philosophy and adopt physics.

28. Bohr, Niels (Henrik David) - Encyclopedia Britannica - On History Full Name Niels Bohr. Nationality Dane Activity Danish physicist. Born 0710-1885 Died 18-11-1962 http://www.history.co.uk/encyclopedia/bohr-niels-henrik-david-.html

29. Niels Bohr Address to the Physical Society of Copenhagen, published in Fysisk Tidsskrift. http://webserver.lemoyne.edu/faculty/giunta/bohr.html

Niels Bohr (1885-1962) On the Spectrum of Hydrogen address to the Physical Society of Copenhagen, December 20, 1913 [ Fysisk Tidsskrift , 97 (1914) translated by A. D. Udden ("The Theory of Spectra and Atomic ConstitutionThree Essays", 1922) from Forest Ray Moulton and Justus J. Schifferes, Eds., Autobiography of Science (New York: Doubleday, 1950)] Hydrogen possesses not only the smallest atomic weight of all the elements, but it also occupies a peculiar position both with regard to its physical and its chemical properties. One of the points where this becomes particularly apparent is the hydrogen line spectrum. The spectrum of hydrogen observed in an ordinary Geissler tube consists of a series of lines, the strongest of which lies at the red end of the spectrum, while the others extend out into the ultra-violet, the distance between the various lines, as well as their intensities, constantly decreasing. In the ultraviolet the series converges to a limit. ... Let us now assume that a hydrogen atom simply consists of an electron revolving around a nucleus of equal and opposite charge, and of a mass which is very large in comparison with that of the electron. It is evident that this assumption may explain the peculiar position already referred to which hydrogen occupies among the elements, but it appears at the outset completely hopeless to attempt to explain anything at all of the special properties of hydrogen, still less its line spectrum, on the basis of considerations relating to such a simple system.

30. Niels Bohr Published by Fysisk Tidsskrift 19, 153. http://webserver.lemoyne.edu/faculty/giunta/bohr2.html

Niels Bohr (1885-1962) The Structure of the Atom and the Physical and Chemical Properties of the Elements Fysisk Tidsskrift , 153 (1921) translated by A. D. Udden, "The Theory of Spectra and Atomic ConstitutionThree Essays" (Cambridge, 1922) [from Forest Ray Moulton and Justus J. Schifferes, Eds., Autobiography of Science (New York: Doubleday, 1950)] So far as the principles of the quantum theory are concerned, the point which has been emphasized hitherto is the radical departure of these principles from our usual conceptions of mechanical and electrodynamical phenomena. As I have attempted to show in recent years, it appears possible, however, to adopt a point of view which suggests that the quantum theory may, nevertheless, be regarded as a rational generalization of our ordinary conceptions. As may be seen from the postulates of the quantum theory, and particularly the frequency relation, a direct connection between the spectra and the motion of the kind required by the classical dynamics is excluded, but at the same time the form of these postulates leads us to another relation of a remarkable nature. Let us consider an electrodynamic system and inquire into the nature of the radiation which would result from the motion of the system on the basis of the ordinary conceptions. We imagine the motion to be decomposed into purely harmonic oscillations, and the radiation is assumed to consist of the simultaneous emission of series of electromagnetic waves possessing the same frequency as these harmonic components and intensities which depend upon the amplitudes of the components.

31. Open Letter To The United Nations Copenhagen, June 9th, 1950 Bohrs attempt to avoid the nuclear arms race. http://www.nba.nbi.dk/files/gym/leth.htm

Niels Bohr OPEN LETTER TO THE UNITED NATIONS June 9 th J. H. SCHULTZ FORLAG COPENHAGEN · DENMARK I address myself to the organization, founded for the purpose to further co-operation between nations on all problems of common concern, with some considerations regarding the adjustment of international relations required by modern development of science and technology. At the same time as this development holds out such great promises for the improvement of human welfare it has, in placing formidable means of destruction in the hands of man, presented our whole civilization with a most serious challenge. My association with the American-British atomic energy project during the war gave me the opportunity of submitting to the governments concerned views regarding the hopes and the dangers which the accomplishment of the project might imply as to the mutual relations between nations. While possibilities still existed of immediate results of the negotiations within the United Nations on an arrangement of the use of atomic energy guaranteeing common security, I have been reluctant in taking part in the public debate on this question. In the present critical situation, however, I have felt that an account of my views and experiences may perhaps contribute to renewed discussion about these matters so deeply influencing international relationship. In presenting here views which on an early stage impressed themselves on a scientist who had the opportunity to follow developments on close hand I am acting entirely on my own responsibility and without consultation with the government of any country. The aim of the present account and considerations is to point to the unique opportunities for furthering understanding and co-operation between nations which have been created by the revolution of human resources brought about by the advance of science, and to stress that despite previous disappointments these opportunities still remain and that all hopes and all efforts must be centered on their realization.

32. Bohr On The Liquid Drop Model Of Fission Bohr on the liquid drop model of fission. Published in Nature. http://www.chemteam.info/Chem-History/Bohr-Fission-1939.html

Disintegration of Heavy Nuclei Niels Bohr Nature vol. 143, p. 330 February 25, 1939 Through the kindness of the authors I have been informed of the content of the letters recently sent to the editor of Nature by Professor Meitner and Dr. Frisch. In the first letter, these authors propose an interpretation of the remarkable findings of Hahn and Strassmann as indication for a new type of disintegration of heavy nuclei, consisting in a fission of the nucleus into two parts of approximately equal masses and charges with release of enormous energy. In the second letter, Dr. Frisch describes experiments in which these parts are directly detected by the very large ionization they produce. Due to the extreme importance of this discovery, I should be glad to add a few comments on the mechanism of the fission process from the point of view of the general ideas, developed in recent years, to account for the main features of the nuclear reactions hitherto observed. In both cases, the course of the disintegration may thus be said to result from a fluctuation in the statistical distribution of the energy between the various degrees of freedom of the system, the probability of occurrence of which is essentially determined by the amount of energy to be concentrated on the particular type of motion considered, and by the "temperature" corresponding to the nuclear excitation. Since the effective cross-sections for the fission phenomena seem to be about the same order of magnitude as the cross-sections for ordinary nuclear reactions, we may therefore conclude that for the heaviest nuclei the deformation energy sufficient for the fission is of the same order of magnitude as the energy necessary for the escape of a single nuclear particle. For somewhat lighter nuclei, however, where only evaporation-like disintegrations have so far been observed, the former energy should be considerably larger than the binding energy of a particle.

33. Bohr, Niels Introduction One of the foremost scientists of the 20th century, Niels Henrik David Bohr was the first to apply the quantum theory, which restricts the energy of a system to http://dwb.unl.edu/Teacher/NSF/C06/C06Links/207.138.35.143/nobel/macro/5000_79.h

Bohr, Niels Bohr By courtesy of the Nobelstiftelsen, Stockholm Introduction One of the foremost scientists of the 20th century, Niels Henrik David Bohr was the first to apply the quantum theory, which restricts the energy of a system to certain discrete values, to the problem of atomic and molecular structure. He was a guiding spirit and major contributor to the development of quantum mechanics and atomic physics . His work on atomic theory was recognized by the Nobel Prize for Physics in 1922. Early life. Bohr was born in Copenhagen on Oct. 7, 1885. His father, Christian Bohr, professor of physiology at the University of Copenhagen, was known for his work on the physical and chemical aspects of respiration. His mother, Ellen Adler Bohr, came from a wealthy Jewish family prominent in Danish banking and parliamentary circles. Bohr's scientific interests and abilities were evident early, and they were encouraged and fostered in a warm, intellectual family atmosphere. Niels's younger brother, Harald, became a brilliant mathematician. Bohr distinguished himself at the University of Copenhagen, winning a gold medal from the Royal Danish Academy of Sciences and Letters for his theoretical analysis of and precise experiments on the vibrations of water jets as a way of determining surface tension. In 1911 he received his doctorate for a thesis on the electron theory of metals that stressed the inadequacies of

34. Bohr On Electronic Structure Of Periodic Table Bohr on electronic structure of the periodic table. Article from Nature. http://www.chemteam.info/Chem-History/Bohr-Nature-1921.html

Atomic Structure Niels Bohr Nature, March 24, 1921 a priori Helium (2 Krypton (2 Neon (2 Xenon (2 Argon (2 Niton (2 where the large figures denote the number of electrons in the groups starting from the innermost one, and the small figures the total number of quanta characterizing the orbits' of electrons with each group. In a fuller account which will be published soon the questions here are discussed will be treated in greater detail. In this letter it is my intention only to direct attention to the possibilities which the elaboration of the principles underlying the spectral applications of the quantum theory seems to open for the interpretation of other properties of the elements. In this connection I should also like to mention that it seems possible, from the examination of the change of the spectra of the elements in the presence of magnetic fields, to develop an argument which promises to throw light on the difficulties which have hitherto been involved in the explanation of the characteristic magnetic properties of the elements, and have been discussed in various letters in NATURE. N. BOHR.

35. Niels Bohr Archive A repository of primary material for the history of modern physics, pertaining in particular to the early development of quantum mechanics and the life and career of Niels Bohr. News, collections, library, publications and seminars. http://www.nba.nbi.dk/

Practical Information People Annual Reports: Previous Collections Photograph Reproduction ... Publications Niels Bohr Archive Topical pages on this site: One hundred years of the Bohr atom, 1913-2013 Call for history of science conference contributions, 2013 Niels Bohr - 125 years, 7th October 2010 George de Hevesy - 125 years, 1st August 2010 Seminars 27 October 2010 Elsevier announces a new complete edition of the Niels Bohr Collected Works. Regarding access to the e-book version see here Niels Bohr Collected Works Completed - with the publication of Volume 12. NBI History Pages: The Institute Niels Bohr Topical photograph Historical Sites of Physical Science in Copenhagen ... Vil du vide noget om Niels Bohr materiale, der omhandler Niels Bohrs liv og arbejde Niels Bohr biography for young people, in Danish In Memoriam Mail address: nba at nbi.dk Web address: www.nba.nbi.dk Last updated: 2010

36. Bohr, Niels Niels (Henrik David) Bohr (October 7, 1885 – November 18, 1962) was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum http://www.newworldencyclopedia.org/entry/Niels_Bohr

Bohr, Niels From New World Encyclopedia Jump to: navigation search Previous (Nicotiana) Next (Niflheim) Niels Bohr Niels Henrik David Bohr Born October 7, 1885 Copenhagen Denmark Died Copenhagen Denmark Nationality Danish Field Physics Institutions University of Copenhagen University of Cambridge University of Copenhagen Christian Christiansen Copenhagen interpretation Complementarity Bohr model Nobel Prize Niels (Henrik David) Bohr (October 7, 1885 – November 18, 1962) was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in 1922. He was also part of the team of physicists working on the Manhattan Project . Bohr married Margrethe Nørlund in 1912, and one of their sons, Aage Niels Bohr, grew up to be an important physicist, who like his father received the Nobel prize. Niels Bohr is widely considered one of the greatest physicists of the twentieth century. Niels Bohr is one of the most important scientists from Denmark; he is depicted on the front of the 500 Danish Kroner banknote and the Institute of Physics, founded by Bohr himself, at the University of Copenhagen is named after him. Contents Key legacy Contributions to physics Biography Kierkegaard's influence on Bohr ... Credits Key legacy In the classical view of how two charged particles behave, an electron and a proton should stick together tightly. A hydrogen atom should be 100,000 times smaller than it actually is. Science, at the start of the twentieth century was in the embarrassing position of not having the least idea of just why matter was stable, as it clearly is.

37. Bohr Model Of The Atom Paper published in the Philosophical Magazine in 1913. http://www.chemteam.info/Chem-History/Bohr/Bohr-1913a.html

On the Constitution of Atoms and Molecules Niels Bohr* Philosophical Magazine Series 6, Volume 26 July 1913, p. 1-25 In order to explain the results of experiments on scattering of a rays by matter Prof. Rutherford** has given a theory of the structure of atoms. According to this theory, the atoms consist of a positively charged nucleus surrounded by a system of electrons kept together by attractive forces from the nucleus; the total negative charge of the electrons is equal to the positive charge of the nucleus. Further, the nucleus is assumed to be the seat of the essential part of the mass of the atom, and to have linear dimensions exceedingly small compared with the linear dimensions of the whole atom. The number of electrons in an atom is deduced to be approximately equal to half the atomic weight. Great interest is to be attributed to this atom-model; for, as Rutherford has shown, the assumption of the existence of nuclei, as those in question, seems to be necessary in order to account for the results of the experiments on large angle scattering of the a rays***.

38. Bohr, Niels Summary | BookRags.com Bohr, Niels. Bohr, Niels summary with encyclopedia entries, research information, and more. http://www.bookrags.com/eb/bohr-niels-eb/

39. Niels Bohr - Wikipédia Dossier interactif sur le physicien dans l encyclop die libre. http://fr.wikipedia.org/wiki/Niels_Bohr

Niels Bohr Un article de Wikipédia, l'encyclopédie libre. Aller à : Navigation rechercher Pour les articles homonymes , voir Bohr Niels Bohr Naissance octobre Copenhague Danemark Décès novembre (à 77 ans) Copenhague Danemark Nationalité Danois Champs Physique mécanique quantique Institution Université de Cambridge Université de Manchester Université de Copenhague Diplômé Université de Copenhague Célèbre pour Modèle de Bohr Principe de complémentarité Interprétation de Copenhague Distinctions Prix Nobel de physique Signature modifier Niels Henrik David Bohr octobre Copenhague Danemark novembre à Copenhague) est un physicien danois . Il est surtout connu pour son apport à l'édification de la mécanique quantique , pour lequel il a reçu de nombreux honneurs. Il est notamment lauréat du prix Nobel de physique de 1922 Sommaire Biographie Distinctions et récompenses Citations Notes et références ... modifier Biographie Né de Christian Bohr professeur de médecine et recteur d'université, de confession luthérienne, et Ellen Adler, d'origine juive, Niels Bohr a un frère cadet, Harald Bohr , mathématicien et sportif de haut niveau (il joua dans l'équipe nationale de football et participa aux Jeux olympiques d'été de 1908 tenus à Londres), ainsi qu'une sœur ainée, Jenny.

40. Bohr, Niels: Encyclopedia Of Science And Religion For the first half of the twentieth century, as both physicist and natural philosopher, Niels Bohr was at the epicenter of the quantum revolution that gave physicists their http://www.enotes.com/science-religion-encyclopedia/bohr-niels

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