Editing Copenhagen interpretation (section)

==Origin and use of the term==
[[File:Niels Bohr Institute 1.jpg|thumb|The [[Niels Bohr Institute]] in Copenhagen]]
The 'Copenhagen' part of the term refers to the city of [[Copenhagen]] in [[Denmark]]. During the mid-1920s, Heisenberg had been an assistant to Bohr at [[Niels Bohr Institute|his institute]] in Copenhagen. Together they helped originate quantum mechanical theory.<ref>{{cite book|editor-first1=Lisa M. |editor-last1=Dolling |editor-first2=Arthur F. |editor-last2=Gianelli |editor-first3=Glenn N. |editor-last3=Statile |chapter=Introduction |title=The Tests of Time: Readings in the Development of Physical Theory |publisher=Princeton University Press |year=2003 |pages=359–370 |doi=10.2307/j.ctvcm4h07.52 |quote=The generally accepted interpretation of Quantum Theory was formulated by Niels Bohr, Werner Heisenberg, and Wolfgang Pauli during the early part of the twentieth century at Bohr's laboratory in Copenhagen, Denmark. This account, commonly referred to as the "Copenhagen Interpretation"...}}</ref><ref>{{cite journal|last=Brush |first=Stephen G. |title=The Chimerical Cat: Philosophy of Quantum Mechanics in Historical Perspective |journal=[[Social Studies of Science]] |volume=10 |number=4 |publisher=Sage Publications, Ltd. |year=1980 |pages=393–447 |doi=10.1177/030631278001000401 |jstor=284918 |s2cid=145727731 |quote=On the other side, Niels Bohr was the leading spokesman for the new movement in physics, and thus it acquired the name 'Copenhagen Interpretation.'}}</ref> At the 1927 [[Solvay Conference]], a dual talk by [[Max Born]] and Heisenberg declared "we consider quantum mechanics to be a closed theory, whose fundamental physical and mathematical assumptions are no longer susceptible of any modification."<ref>{{Cite book|last1=Bacciagaluppi|first1=Guido|url=https://books.google.com/books?id=EAPX3JfQAgIC|title=Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference|last2=Valentini|first2=Antony|date=2009-10-22|publisher=Cambridge University Press|isbn=978-0-521-81421-8|pages=408|language=en}} (This book contains a translation of the entire authorized proceedings of the 1927 Solvay conference from the original transcripts.)</ref><ref name=":5">{{Cite journal|last=Bokulich|first=Alisa|date=2006|title=Heisenberg Meets Kuhn: Closed Theories and Paradigms|url=https://www.jstor.org/stable/10.1086/510176|journal=[[Philosophy of Science (journal)|Philosophy of Science]] |volume=73|issue=1|pages=90–107|doi=10.1086/510176|jstor=10.1086/510176|s2cid=170902096|issn=0031-8248|url-access=subscription}}</ref> In 1929, Heisenberg gave a series of invited lectures at the [[University of Chicago]] explaining the new field of quantum mechanics. The lectures then served as the basis for his textbook, ''[[The Physical Principles of the Quantum Theory]]'', published in 1930.<ref>{{cite book|last1=Mehra|first1=J.|title=The Historical Development of Quantum Theory: Volume 4|last2=Rechenberg|first2=H.|publisher=Springer-Verlag|year=2001|isbn=9780387906423|page=266|oclc=928788723|author-link1=Jagdish Mehra|author-link2=Helmut Rechenberg}}</ref>  In the book's preface, Heisenberg wrote:

<blockquote>On the whole, the book contains nothing that is not to be found in previous publications, particularly in the investigations of Bohr.  The purpose of the book seems to me to be fulfilled if it contributes somewhat to the diffusion of that 'Kopenhagener Geist der Quantentheorie' [Copenhagen spirit of quantum theory] if I may so express myself, which has directed the entire development of modern atomic physics.</blockquote>

The term 'Copenhagen interpretation' suggests something more than just a spirit, such as some definite set of rules for interpreting the mathematical formalism of quantum mechanics, presumably dating back to the 1920s.<ref>See, for example:
*{{cite journal|last=Smith |first=Quentin |title=The Ontological Interpretation of the Wave Function of the Universe |journal=[[The Monist]] |volume=80 |number=1 |publisher=Oxford University Press |year=1997 |pages=160–185 |doi=10.5840/monist19978015 |jstor=27903516 |quote=Since the late 1920s, the orthodox interpretation was taken to be the Copenhagen Interpretation}}
*{{cite book|first=Steven |last=Weinberg |author-link=Steven Weinberg |chapter=The Trouble with Quantum Mechanics |title=Third Thoughts |publisher=Harvard University Press |year=2018 |pages=124–142 |doi=10.2307/j.ctvckq5b7.17 |jstor=j.ctvckq5b7.17 |isbn=9780674975323 |quote=One response to this puzzle was given in the 1920s by Niels Bohr, in what came to be called the Copenhagen interpretation of quantum mechanics.}}
*{{cite journal|last=Hanson |first=Norwood Russell |author-link=Norwood Russell Hanson |title=Five Cautions for the Copenhagen Interpretation's Critics |journal=[[Philosophy of Science (journal)|Philosophy of Science]] |volume=26 |number=4 |publisher=The University of Chicago Press, Philosophy of Science Association |year=1959 |pages=325–337 |doi=10.1086/287687 |jstor=185366 |s2cid=170786589 |quote=Feyerabend and Bohm are almost exclusively concerned with the inadequacies of the Bohr-Interpretation (which originates in Copenhagen). Both understress a much less incautious view, which ''I'' shall call 'the Copenhagen Interpretation' (which originates in Leipzig and presides at Göttingen, Munich, Cambridge, Princeton,―and almost everywhere else too).}}</ref> However, no such text exists, and the writings of Bohr and Heisenberg contradict each other on several important issues.<ref name="camilleri2015"/> It appears that the particular term, with its more definite sense, was coined by Heisenberg around 1955,<ref name="Howard 2004">{{cite journal |title=Who invented the Copenhagen Interpretation? A study in mythology |year=2004 |last1=Howard |first1=Don |journal=[[Philosophy of Science (journal)|Philosophy of Science]] |pages=669–682 | jstor=10.1086/425941 |volume=71 |issue=5 |doi=10.1086/425941|url=http://www.nd.edu/~dhoward1/Copenhagen%20Myth%20A.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://www.nd.edu/~dhoward1/Copenhagen%20Myth%20A.pdf |archive-date=2022-10-10 |url-status=live |citeseerx=10.1.1.164.9141 |s2cid=9454552 }}</ref> while criticizing alternative "interpretations" (e.g., [[David Bohm]]'s<ref>{{cite journal |title=A Suggested Interpretation of the Quantum Theory in Terms of 'Hidden' Variables. I & II|year=1952 |last1=Bohm |first1=David |journal=[[Physical Review]] |volume=85 |issue=2 |pages=166–193 |bibcode=1952PhRv...85..166B |doi=10.1103/PhysRev.85.166 }}</ref>) that had been developed.<ref>{{cite book|first=H. |last=Kragh |author-link=Helge Kragh |title=Quantum Generations: A History of Physics in the Twentieth Century |publisher=Princeton University Press |year=1999 |page=210 |isbn=978-0-691-01206-3 |oclc=450598985 |quote=In fact, the term 'Copenhagen interpretation' was not used in the 1930s but first entered the physicists' vocabulary in 1955 when Heisenberg used it in criticizing certain unorthodox interpretations of quantum mechanics.}}</ref><ref name="Camilleri 2009">{{Cite journal|last=Camilleri|first=Kristian|date=May 2009|title=Constructing the Myth of the Copenhagen Interpretation|url=http://www.mitpressjournals.org/doi/10.1162/posc.2009.17.1.26|journal=[[Perspectives on Science]] |language=en |volume=17 |issue=1 |pages=26–57 |doi=10.1162/posc.2009.17.1.26 |s2cid=57559199 |issn=1063-6145|url-access=subscription }}</ref>  Lectures with the titles 'The Copenhagen Interpretation of Quantum Theory' and 'Criticisms and Counterproposals to the Copenhagen Interpretation', that Heisenberg delivered in 1955, are reprinted in the collection ''Physics and Philosophy''.<ref name="Heisenberg 1958">{{cite book|first=Werner |last=Heisenberg |title=Physics and Philosophy |publisher=Harper |year=1958}}</ref>  Before the book was released for sale, Heisenberg privately expressed regret for having used the term, due to its suggestion of the existence of other interpretations, that he considered to be "nonsense".<ref>"I avow that the term ‘Copenhagen interpretation’ is not happy since it could suggest that there are other interpretations, like Bohm assumes. We agree, of course, that the other interpretations are nonsense, and I believe that this is clear in my book, and in previous papers. Anyway, I cannot now, unfortunately, change the book since the printing began enough time ago." Quoted in {{cite journal|first=Olival Jr. |last=Freire |title=Science and exile: David Bohm, the hot times of the Cold War, and his struggle for a new interpretation of quantum mechanics |journal=[[Historical Studies in the Natural Sciences|Historical Studies in the Physical and Biological Sciences]] |volume=36 |number=1 |year=2005 |pages=31–35|doi=10.1525/hsps.2005.36.1.1 }}</ref> In a 1960 review of Heisenberg's book, Bohr's close collaborator [[Léon Rosenfeld]] called the term an "ambiguous expression" and suggested it be discarded.<ref>{{cite journal|last=Rosenfeld |first=Léon |author-link=Léon Rosenfeld |year=1960 |title=Heisenberg, Physics and Philosophy |journal=[[Nature (journal)|Nature]] |volume=186 |issue=4728 |pages=830–831 |doi=10.1038/186830a0|bibcode=1960Natur.186..830R |s2cid=12979706 }}</ref> However, this did not come to pass, and the term entered widespread use.<ref name="Howard 2004"/><ref name="Camilleri 2009"/> Bohr's ideas in particular are distinct despite the use of his Copenhagen home in the name of the interpretation. <ref>{{cite book |last=Scheibe |first=Erhard |title=The Logical Analysis of Quantum Mechanics |publisher=Pergamon Press |year=1973 |isbn=978-0-08-017158-6 |oclc=799397091 |quote=[T]here is no point in looking for ''the'' Copenhagen interpretation as a unified and consistent logical structure. Terms such as "Copenhagen interpretation" or "Copenhagen school" are based on the history of the development of quantum mechanics; they form a simplified and often convenient way of referring to the ideas of a number of physicists who played an important role in the establishment of quantum mechanics, and who were collaborators of Bohr's at his Institute or took part in the discussions during the crucial years. On closer inspection, one sees quite easily that these ideas are divergent in detail and that in particular the views of Bohr, the spiritual leader of the school, form a separate entity which can now be understood only by a thorough study of as many as possible of the relevant publications by Bohr himself. |author-link=Erhard Scheibe}}</ref>