12 June 1999, “Interest in Pauli” I have come across a reference to a paper of yours that I have not been able to obtain. May I ask of you to send me a reprint of it? The paper is: C. P. Enz, “Wolfgang Pauli and the Role of the Observer in Modern Physics,” in Philosophy of the Natural Sciences: Proceedings of the 13th International Wittgenstein Symposium , edited by P. Weingartner and G. Schurz (Verlag Holder–Pichler–Temsky, Vienna, 1989), pp. 110–119. I have read several of your other papers on Pauli's thought and have been uniformly pleased with each. I am especially interested in his ideas concerning the demise of the “detached-observer” notion within quantum theory. (I would also be interested in any of your other works on the subject that may have been written since your 1992 article, “Wolfgang Pauli between Quantum Reality and the Royal Path of Dreams.” This is the latest one that I am aware of.) About myself, I am a theoretical physicist at Caltech who specializes in quantum information theory and quantum computing. I am well acquainted with your colleague Nicolas Gisin at the University of Geneva. 21 August 1999, “One More Article?” Upon my return from Cambridge a couple of weeks ago, I found in my mailbox your package full of wonderful papers! Thank you so much.
12 June 1999, “Interest in Pauli” I have come across a reference to a paper of yours that I have not been able to obtain. May I ask of you to send me a reprint of it? The paper is: C. P. Enz, “Wolfgang Pauli and the Role of the Observer in Modern Physics,” in Philosophy of the Natural Sciences: Proceedings of the 13th International Wittgenstein Symposium , edited by P. Weingartner and G. Schurz (Verlag Holder–Pichler–Temsky, Vienna, 1989), pp. 110–119. I have read several of your other papers on Pauli's thought and have been uniformly pleased with each. I am especially interested in his ideas concerning the demise of the “detached-observer” notion within quantum theory. (I would also be interested in any of your other works on the subject that may have been written since your 1992 article, “Wolfgang Pauli between Quantum Reality and the Royal Path of Dreams.” This is the latest one that I am aware of.) About myself, I am a theoretical physicist at Caltech who specializes in quantum information theory and quantum computing. I am well acquainted with your colleague Nicolas Gisin at the University of Geneva. 21 August 1999, “One More Article?” Upon my return from Cambridge a couple of weeks ago, I found in my mailbox your package full of wonderful papers! Thank you so much.
January 1999, “The (Un-)Detached Observer” Yesterday I ran across your paper “On the Interpretation and Philosophical Foundation of Quantum Mechanics” posted on the web, and was very much impressed with its depth. Most importantly, however, I am sad to say, it reminded me that I still owe you some papers. I have remedied that now by sending you a pile of things that I have written on the relation between information gain and quantum state disturbance. These are relevant to your request above, and, I think, even more relevant to the thoughts in your paper. I am in great agreement with the idea that there may be a deeper foundation to quantum mechanics, one along the lines that Pauli and Wheeler attempted to sketch. Quantum mechanics, it seems to me, is an expression of the best we can say in a world where the observer is not detached (to use Pauli's phrase). Recognizing and appreciating that lack of detachedness is the most exacting tool we have for peering into the greater future of quantum theory. This I think is the ultimate role of quantum information theory. (For the opposite point of view, however, you may be interested in having a look at John Preskill's paper “Quantum Information: Its Future Impact on Physics” at http://theory.caltech.edu/~preskill/.) I hope you will enjoy the things I have sent you; it is always my attempt to be as clear as I possibly can be when I write.
22 August 1999, “Your Article” I am writing to let you know that I enjoyed your article quant-ph/9812050, “Why Quantum Mechanics is Hard to Understand,” very much. I was in particular very pleased with your Section IV “Dynamics vs. History.” It may interest you to know that Markus Fierz expressed a similar point of view in his article: “Does a physical theory comprehend an ‘objective, real, single process’?” in Observation and Interpretation in the Philosophy of Physics , edited by S. Körner (Dover, NY, 1957), pp. 93–96. I will append the full text below for your enjoyment. [See note to Rüdiger Schack, dated 29 August 1999.] Most importantly, I would like to ask you for the final coordinates of your paper. Was it published somewhere? I would like to cite it in an upcoming paper. 28 August 1999, “Not Much” I don't have a good idea about where to send your paper. I think chances are that AJP will be tougher than FP . In any case, it had an impact on me. My old advisor used to say of our joint papers, “If three people read this paper, we'll be doing OK!” If you know of two others with yours, you're probably doing OK. I like this focus on the concept of “object.” I look forward to anything you might have to say about it. I have some slides that I use as a rallying cry to the idea that quantum information theory may have some impact on quantum foundations. The first is a list of axioms for quantum mechanics.
Open realism, B. d'Espagnat quantum mechanics and objectivity - an analysis of some paradoxes, A. Peres non-locality and wave-packet reduction in optical experiments - physical and philosophical issues in the Bohr-Einstein debate, A. Shimony actualization perception and reality - an epistemological approach based on psychological analysis - a draft, K. Rainio do we need an introvert physics?, E. Huhmar quantum theory of measurement - a review, P. Lahti the archetypal hypothesis of Wolfgang Pauli and C.G. Junge - origins, development and implications, C.R. Card Wolfgang Pauli between quantum reality and the royal path of dreams, C.P. Enz Einstein, Bohr, Pauli and the principle of individuation, H. van Erkelens the role of the Copenhagen interpretation today - quantum mechanics and realism, remarks on physics and the psyche, K.V. Laurikainen the Cartesian cut, the Heisenberg cut, dressed objects, and detached observers, H. Primas mind, matter, and Pauli, H. Stapp a possible explanation for the quantum structure, D. Aerts the observer in the age of man - from Laplace's demon to Wigner's friend, F. Borg universal gravitational interaction and the (non)-measurability of physical field quantities, on a new type of uncertainty relations in quantum general relativity, H-H. v. Borzeskowski non-detachability of language and the Pauli-Bohr dialogue, L. Lofgren quantum mechanics as a continuous theory of discrete processes, P. Sibelius.
February 2000, “The Quantum View” What a really nice article! I read it once this evening with dinner (at a place that served grilled chicken – not so easy to scroll through a computer screen under those conditions!). Now, with my jetlag in distinct control – its 3:30 AM for me – let me read it again and make a few comments here and there. (I just arrived in Haifa yesterday for a visit with Asher Peres; I'll be here a little over a week.) Why don't you write the following for your requested reference: C. A. Fuchs, “The Structure of Quantum Information,” available at […] [Of course, it is no longer available. Instead, see note to Carl Caves, dated 21 December 1997.] I like this view of physics as being like a jig-saw puzzle. Note a typo in this paragraph: you misspelled de Broglie. Ruskai-ism 1: As far as I am aware, there is no evidence that either Heisenberg or Schrödinger was motivated by political or social factors . Actually there is a pretty strong case that these two guys were indeed quite motivated by cultural factors to find an indeterministic element in physics. And that was long before quantum mechanics took a final form. Two important articles to read in this regard are: P. Forman, “Weimar Culture, Causality, and Quantum Theory, 1918–1927: Adaptation by German Physicists and Mathematicians to a Hostile Intellectual Environment,” in Historical Studies in the Physical Sciences, Vol. 3 , edited by R. McCormmach (U. Pennsylvania Press, Philadelphia, 1971), pp. 1–115. […]
Fifteen years ago, I mused in a Reference Frame column on how different generations of physicists differed in the degree to which they thought that the interpretation of quantum mechanics remains a serious problem. I declared myself to be among those who feel uncomfortable when asked to articulate what we really think about the quantum theory, adding that “If I were forced to sum up in one sentence what the Copenhagen interpretation says to me, it would be ‘Shut up and calculate!’” In the intervening years, I've come to hold a milder and more nuanced opinion of the Copenhagen view, but that should be the subject of another column. The subject of this one is the habit of misquotation or misattribution that afflicts our profession, a rather different example of which I pointed out a few months ago. Given my capacity for intellectual development (“inconsistency,” in the terminology deployed in the current American political season), it's fortunate that I've now reached an age at which I tend to forget about things I've written more than a few years ago. Indeed, I find it downright irritating when somebody asks me questions about papers I wrote a mere half dozen years ago, naively identifying me with the author of those ancient texts. Until quite recently, I had no memory of ever having written such a childishly brusque dismissal of such an exquisitely subtle point of view, much less of having published it in so widely read a venue. This amnesia, combined with the evolution in my thinking that had distanced me from my long-forgotten words, may explain why I was initially somewhat puzzled by the slight sensation of discomfort that passed over me when, browsing the e-print archive earlier this year, I read a characterization of Max Born's probability rule as “the favorite ingredient of what has been nicknamed, after Feynman's famous dictum, the shut up and calculate interpretation of quantum mechanics.” I yield to nobody in my admiration for Richard Feynman's aphorisms on the nature of quantum mechanics. Indeed, long ago I published a poem consisting of nothing more than a resetting as verse of a paragraph Feynman had written about his own attitude toward the quantum theory, in his now (but not then) famous article that launched the whole field of quantum computation. I like to think I have devoured everything Feynman ever wrote on the character of quantum mechanics.