Physics Today
Mermin habitually answers opinions, real and abstract
A. Burov
Published Sep 1, 2009• 0 citations
Abstract
David Mermin seems to advocate the view of theoretical paradoxes and controversies of quantum mechanics and field theory as problems of “tools” of a linguistic or otherwise technical nature. His advice is not to “make life harder than it needs to be.” First, philosophical reduction of a fundamental science to a human tool goes against the main quest of science – the quest for objective truth about the universe. Second, the suggested advice seems more conducive to peace of mind than to scientific inquiry. Paradoxes and contradictions have always been a rich source of inspiration and contemplation for those who are seeking new knowledge.© 2009 American Institute of Physics.
- DOI
- 10.1063/1.4797207
Related papers
Mermin habitually answers opinions, real and abstract
Mark Alford
David Mermin criticizes the “reification” of magnetic fields, but he allows that spark chamber trajectories and atomic spectra are real, so why not also accept magnetic fields, ionic lattices, the cosmic microwave background, and so on? And is reification such a bad habit? Intuitive flashes of insight come as much from immersing yourself in the reality of the physics as from holding your nose and manipulating formal symbols. Often, reification leads us in the right direction: I assume Mermin has no plans to revive Mach’s crusade against the reality of the atom.I sympathize with Mermin’s desire to distinguish between mathematical abstractions like quantum field operators and solid realities like metals, but by any reasonable standard, magnetic fields are just as real as equally invisible variations in air pressure. Mermin worries that quantum mechanics describes fields—and atoms and everything else—in weird abstract terms, but allowing the weirdness of quantum mechanics to undermine the normal concept of what is real seems like a case of taking a successful theory too seriously, which is just what he was warning us not to do.© 2009 American Institute of Physics.
Physics Today•Sep 1, 2009•0 citations
Mermin habitually answers opinions, real and abstract
Philip Pearle
David Mermin cautions against taking our “most successful abstractions to be real properties of our world.” I think he has set up a straw man. To me, the tenable realist position is not that our concepts are real but rather that they have a correspondence to reality: There can be many such correspondences, each with its utility, none capturing reality—whatever that is.I am not surprised he uses that argument to bolster the position “that quantum states are calculational devices.” In the vein of the disagreement about reality he cites, between Bishop Berkeley and Samuel Johnson, I recall a similar disagreement, between Mermin and John Bell, concerning the foundations of quantum theory. It took place at a meeting in Erice, Italy, in August 1989. Bell had finished his now famous talk “Against ‘Measurement,’ “ in which he argued that there is something wrong with quantum theory, that its rules of application are ill-defined. 1 1. J. Bell, Sixty-Two Years of Uncertainty, A. Miller, ed., Plenum, New York (1990), p. 17, https://doi.org/10.1007/978-1-4684-8771-8_3 reproduced in Phys. World 3, 33 (August 1990). He introduced the acronym FAPP, meaning that quantum theory is good “for all practical purposes” but insufficient for a truly fundamental theory. In the question-and-answer session, Mermin gave an argument not unlike the one in his Reference Frame. When he was done, Bell replied, “FAPPtrap,” and that was that.Mermin says that if one takes his view, it “can diminish the motivation for theoretical or experimental searches for a ‘mechanism’ underlying … the ‘collapse of the wavefunction’—searches that make life harder than it needs to be.” But why would one want to diminish such motivation? Might not the deficiencies of quantum theory elucidated by Bell be a clue to some deeper theory? And is that not good for physics? Certainly, in this generation, in which we did not predict the acceleration of the universe nor know the nature of dark energy or dark matter, we should have the humility to think that perhaps we do not yet have the “final” quantum theory. For example, in standard quantum theory, how or why an event occurs is a complete mystery. Nature determines an outcome, but we are told it is impossible for us to understand that in terms of anything deeper. Things happen for no reason at all. Why should we follow Mermin’s advice and not try to do better?In my own work and that of Gian-Carlo Ghirardi, Alberto Rimini, and Tullio Weber, we have developed what is called a dynamical theory of wave-function collapse (continuous spontaneous localization, or CSL). 2 2. Two reviews are P. Pearle in Open Systems and Measurement in Relativistic Quantum Field Theory, H. P. Breuer, F. Petruccionne, eds., Springer, Berlin (1999), p. 195 and A. Bassi, G. C. Ghirardi, Phys. Rep. 379, 257 (2003). https://doi.org/10.1016/S0370-1573(03)00103-0 To Schrödinger’s equation, a term is added that describes the interaction of matter with a randomly fluctuating field, so that a state vector in a superposition of macroscopically different states rapidly evolves to one of them. The final state describes the world as we see it. Therefore, the state vector can be said to correspond to reality and not be merely a computational device. Bell regarded CSL as an example of a well-defined theory, which overcomes his objections to standard quantum theory. Moreover, it provides a mechanism, a description, for the occurrence of events. And it makes some predictions that differ from those of standard quantum theory, so it is experimentally testable. Experiments so far have shown that the coupling of random field to matter must be mass proportional, but otherwise they have neither confirmed CSL nor denied it. This is a good thing, and that such attempts should not be discouraged, as Mermin’s article does, was underlined by Richard Feynman, who said in 1964,We have to find a new view of the world that has to agree with everything that is known, but disagree in its predictions somewhere, otherwise it is not interesting. And in that disagreement it must agree with nature. If you can find any other view of the world which agrees over the entire range where things have already been observed, but disagrees somewhere else, you have made a great discovery. It is very nearly impossible, but not quite, to find any theory which agrees with experiments over the entire range in which all theories have been checked, and yet gives different consequences in some other range, even a theory whose different consequences do not turn out to agree with nature. 3 3. R. Feynman, in The Character of Physical Law, MIT Press, Cambridge, MA (1970), p. 171. REFERENCESSection:ChooseTop of pageREFERENCES <<1. J. Bell, Sixty-Two Years of Uncertainty, A. Miller, ed., Plenum, New York (1990), p. 17, https://doi.org/10.1007/978-1-4684-8771-8_3 , Google ScholarCrossrefreproduced in Phys. World 3, 33 (August 1990). , Google Scholar2. Two reviews are P. Pearle in Open Systems and Measurement in Relativistic Quantum Field Theory, H. P. Breuer, F. Petruccionne, eds., Springer, Berlin (1999), p. 195 and , Google ScholarCrossref A. Bassi, G. C. Ghirardi, Phys. Rep. 379, 257 (2003). https://doi.org/10.1016/S0370-1573(03)00103-0 , , Google ScholarCrossref, ISI3. R. Feynman, in The Character of Physical Law, MIT Press, Cambridge, MA (1970), p. 171. Google Scholar© 2009 American Institute of Physics.
Physics Today•Sep 1, 2009•0 citations
Mermin habitually answers opinions, real and abstract
Fred Kuttner, Bruce Rosenblum
David Mermin tells us that our “bad habit” of reifying the quantum state “induces people to write books and organize conferences about ‘the quantum measurement problem.’ “ However, a quantum measurement problem does not arise only from an unfortunate perspective on quantum theory. A quantum measurement problem, as close to magic as anything in science, is displayed in quantum-theory-neutral experimental observations that assume only the free choice of the experimenters. In the two-slit experiment, one can choose to demonstrate each object concentrated at a single slit or perform the contradictory demonstration, that each object spread over both slits. Facing this dilemma, George Greenstein and Arthur Zajonc note that “even had quantum theory never been invented, these [two-slit] experiments could have been performed, and we would still find ourselves unable to understand them.” 1 1. G. Greenstein, A. Zajonc, The Quantum Challenge: Modern Research on the Foundations of Quantum Mechanics, 2nd ed., Jones and Bartlett, Sudbury, MA (2006), p. 124. Quantum weirdness is increasingly misappropriated as a way to buttress pseudoscience. It is a responsibility of physicists to combat such misappropriation. (See our letter in Physics Today, November 2006, page 14.)Presenting the intriguing strangeness of quantum mechanics honestly and interestingly by the use of books Mermin might seem to deplore can effectively combat the misuse of the quantum mysteries. Dismissing the measurement problem as merely a bad way of viewing quantum theory abandons a fascinating mystery in physics to the purveyors of pseudoscience.REFERENCESection:ChooseTop of pageREFERENCE <<1. G. Greenstein, A. Zajonc, The Quantum Challenge: Modern Research on the Foundations of Quantum Mechanics, 2nd ed., Jones and Bartlett, Sudbury, MA (2006), p. 124. Google Scholar© 2009 American Institute of Physics.
Physics Today•Sep 1, 2009•0 citations
Mermin habitually answers opinions, real and abstract
Rodney Brooks
I am that friend of David Mermin’s “who was enchanted by the revelation that quantum fields were the real stuff that makes up the world.” I plead guilty to reification and offer the following defense.I started out, as I think we all did, with the notion that there is a reality out there and that space and time are part of it—not just “an extremely effective way to represent relations between distinct events.” When I read Arthur Eddington’s The Nature of the Physical World (J. M. Dent & Sons, 1942) in high school, I learned that reality was not what it seemed—that Eddington’s solid writing desk, for example, was mostly empty space. The next step in my understanding of reality came in college when I found that the electromagnetic field offered a more satisfying picture of the world than action at a distance, which even Isaac Newton derided. 1 1. H. Boorse, L. Motz, eds., The World of the Atom, Basic Books, New York (1966), p. 319. When I encountered quantum mechanics, of course, everything became confusion. However, along with David, I was fortunate to attend Julian Schwinger’s courses at Harvard University just after he had perfected his treatment of quantum field theory. 2 2. J. Schwinger, Ann. Phys. 2, 407 (1957). https://doi.org/10.1016/0003-4916(57)90015-5 I sat enthralled throughout the three-year series (1956–59), in which Schwinger developed QFT as a seemingly inevitable consequence of the most basic assumptions.However, I came away with a different understanding of QFT than David’s. I understood that the fields are physical properties of space that are described by field strengths—just as in classical physics, except that in QFT the state of the field at each point is represented by a vector in Hilbert space rather than by a pure number. That use of Hilbert space, which followed naturally from Schwinger’s “measurement algebra,” allows superpositions of values. The operators in Hilbert space, as I understood it, are mathematical tools that describe the evolution of the state vectors, and they are not to be reified.When I saw how QFT resolves the paradoxes of modern physics, it became irresistible. The special relativity paradoxes—for example, Lorentz contraction and time dilation—are a natural result of the way fields behave. 3 3. J. Schwinger wrote a six-part series on the theory of quantized fields: Phys. Rev. 82, 914 (1951); 91, 713 (1953); https://doi.org/10.1103/PhysRev.82.914 91, 728 (1953); 92, 1283 (1953); 93, 615 (1954); 94, 1362 (1954). The spacetime curvature of general relativity, which I could never really visualize, does not exist in QFT; the gravitational field equations are equivalent to spacetime curvature for those who can visualize it, but equivalent is not the same as identical. 4 4. S. Weinberg, Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity, Wiley, New York (1972), pp. vii–147. Finally, the mysterious wave–particle duality of quantum mechanics vanishes; in QFT, reality consists of fields and only fields.Because QFT is so neglected by the public (and by many physicists), I am writing a book that presents it without equations. A draft copy of the work, The Theory That Escaped Einstein, can be found through an internet search. Feedback is appreciated.For those who can’t kick the reification habit, QFT is the way to go. It is the only theory that offers a consistent and visualizable picture of reality. Reifiers of the world, unite! You have nothing to lose but your abstractions.REFERENCESSection:ChooseTop of pageREFERENCES <<1. H. Boorse, L. Motz, eds., The World of the Atom, Basic Books, New York (1966), p. 319. Google Scholar2. J. Schwinger, Ann. Phys. 2, 407 (1957). https://doi.org/10.1016/0003-4916(57)90015-5 , Google ScholarCrossref, ISI3. J. Schwinger wrote a six-part series on the theory of quantized fields: Phys. Rev. 82, 914 (1951); 91, 713 (1953); https://doi.org/10.1103/PhysRev.82.914 , Google ScholarCrossref, ISI 91, 728 (1953); , Google Scholar 92, 1283 (1953); Google Scholar 93, 615 (1954); Google Scholar 94, 1362 (1954). Google Scholar4. S. Weinberg, Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity, Wiley, New York (1972), pp. vii–147. Google Scholar© 2009 American Institute of Physics.
Physics Today•Sep 1, 2009•0 citations
Mermin habitually answers opinions, real and abstract
D. Walton
I thoroughly enjoyed David Mermin’s May 2009 Reference Frame. However, definitions of the terms “abstraction” and “reality” are necessary. Unfortunately, that is an extraordinarily difficult task. I offer here the admittedly naive concepts I employed in attempting to understand his essay.Reality is that which can be observed; this is, presumably, what Bertrand Russell meant when he stated that the proof of a concept lies in its comparison with reality. Observations, though, don’t always lead to unique interpretations: Entanglement can be fancifully interpreted as action at a distance, when it is really the result of two particles being produced by a single quantum state that requires that they obey the conservation laws applicable to the particular state.If anything is ever detected, or is prevented from passing between two entangled particles, action at a distance would be confirmed. In the absence of such evidence, I prefer the less exotic explanations.We humans are attracted to fanciful models that are often more exciting than reality; so I agree with Mermin’s basic premise. But I cannot always be confident of distinguishing a real property from a fanciful abstraction. In fact, if pushed, I would have to admit I’m not sure what a real property really is. Possibly Mermin can enlighten me.© 2009 American Institute of Physics.
Physics Today•Sep 1, 2009•0 citations
David Mermin seems to advocate the view of theoretical paradoxes and controversies of quantum mechanics and field theory as problems of “tools” of a linguistic or otherwise technical nature. His advice is not to “make life harder than it needs to be.” First, philosophical reduction of a fundamental science to a human tool goes against the main quest of science – the quest for objective truth about the universe. Second, the suggested advice seems more conducive to peace of mind than to scientific inquiry. Paradoxes and contradictions have always been a rich source of inspiration and contemplation for those who are seeking new knowledge.© 2009 American Institute of Physics.
David Mermin criticizes the “reification” of magnetic fields, but he allows that spark chamber trajectories and atomic spectra are real, so why not also accept magnetic fields, ionic lattices, the cosmic microwave background, and so on? And is reification such a bad habit? Intuitive flashes of insight come as much from immersing yourself in the reality of the physics as from holding your nose and manipulating formal symbols. Often, reification leads us in the right direction: I assume Mermin has no plans to revive Mach’s crusade against the reality of the atom.I sympathize with Mermin’s desire to distinguish between mathematical abstractions like quantum field operators and solid realities like metals, but by any reasonable standard, magnetic fields are just as real as equally invisible variations in air pressure. Mermin worries that quantum mechanics describes fields—and atoms and everything else—in weird abstract terms, but allowing the weirdness of quantum mechanics to undermine the normal concept of what is real seems like a case of taking a successful theory too seriously, which is just what he was warning us not to do.© 2009 American Institute of Physics.
I am curious to hear David Mermin’s view, in light of his May 2009 Reference Frame, of Galileo’s condemnation by the church.That episode is still considered a scandal by most scientists. For example, several physicists cited the Galileo affair as their reason for opposing the visit of Pope Benedict XVI to the University of Rome I (“La Sapienza”) last year.Could we perhaps say that Mermin would agree with those who refuse to recognize any objective truth in physical theories yet support them as useful descriptions of successions of events, thus condemning Galileo’s quest for ontologically realistic theories?Is the proposition that Earth travels around the Sun ultimately a mere calculational device?© 2009 American Institute of Physics.
David Mermin cautions against taking our “most successful abstractions to be real properties of our world.” I think he has set up a straw man. To me, the tenable realist position is not that our concepts are real but rather that they have a correspondence to reality: There can be many such correspondences, each with its utility, none capturing reality—whatever that is.I am not surprised he uses that argument to bolster the position “that quantum states are calculational devices.” In the vein of the disagreement about reality he cites, between Bishop Berkeley and Samuel Johnson, I recall a similar disagreement, between Mermin and John Bell, concerning the foundations of quantum theory. It took place at a meeting in Erice, Italy, in August 1989. Bell had finished his now famous talk “Against ‘Measurement,’ “ in which he argued that there is something wrong with quantum theory, that its rules of application are ill-defined. 1 1. J. Bell, Sixty-Two Years of Uncertainty, A. Miller, ed., Plenum, New York (1990), p. 17, https://doi.org/10.1007/978-1-4684-8771-8_3 reproduced in Phys. World 3, 33 (August 1990). He introduced the acronym FAPP, meaning that quantum theory is good “for all practical purposes” but insufficient for a truly fundamental theory. In the question-and-answer session, Mermin gave an argument not unlike the one in his Reference Frame. When he was done, Bell replied, “FAPPtrap,” and that was that.Mermin says that if one takes his view, it “can diminish the motivation for theoretical or experimental searches for a ‘mechanism’ underlying … the ‘collapse of the wavefunction’—searches that make life harder than it needs to be.” But why would one want to diminish such motivation? Might not the deficiencies of quantum theory elucidated by Bell be a clue to some deeper theory? And is that not good for physics? Certainly, in this generation, in which we did not predict the acceleration of the universe nor know the nature of dark energy or dark matter, we should have the humility to think that perhaps we do not yet have the “final” quantum theory. For example, in standard quantum theory, how or why an event occurs is a complete mystery. Nature determines an outcome, but we are told it is impossible for us to understand that in terms of anything deeper. Things happen for no reason at all. Why should we follow Mermin’s advice and not try to do better?In my own work and that of Gian-Carlo Ghirardi, Alberto Rimini, and Tullio Weber, we have developed what is called a dynamical theory of wave-function collapse (continuous spontaneous localization, or CSL). 2 2. Two reviews are P. Pearle in Open Systems and Measurement in Relativistic Quantum Field Theory, H. P. Breuer, F. Petruccionne, eds., Springer, Berlin (1999), p. 195 and A. Bassi, G. C. Ghirardi, Phys. Rep. 379, 257 (2003). https://doi.org/10.1016/S0370-1573(03)00103-0 To Schrödinger’s equation, a term is added that describes the interaction of matter with a randomly fluctuating field, so that a state vector in a superposition of macroscopically different states rapidly evolves to one of them. The final state describes the world as we see it. Therefore, the state vector can be said to correspond to reality and not be merely a computational device. Bell regarded CSL as an example of a well-defined theory, which overcomes his objections to standard quantum theory. Moreover, it provides a mechanism, a description, for the occurrence of events. And it makes some predictions that differ from those of standard quantum theory, so it is experimentally testable. Experiments so far have shown that the coupling of random field to matter must be mass proportional, but otherwise they have neither confirmed CSL nor denied it. This is a good thing, and that such attempts should not be discouraged, as Mermin’s article does, was underlined by Richard Feynman, who said in 1964,We have to find a new view of the world that has to agree with everything that is known, but disagree in its predictions somewhere, otherwise it is not interesting. And in that disagreement it must agree with nature. If you can find any other view of the world which agrees over the entire range where things have already been observed, but disagrees somewhere else, you have made a great discovery. It is very nearly impossible, but not quite, to find any theory which agrees with experiments over the entire range in which all theories have been checked, and yet gives different consequences in some other range, even a theory whose different consequences do not turn out to agree with nature. 3 3. R. Feynman, in The Character of Physical Law, MIT Press, Cambridge, MA (1970), p. 171. REFERENCESSection:ChooseTop of pageREFERENCES <<1. J. Bell, Sixty-Two Years of Uncertainty, A. Miller, ed., Plenum, New York (1990), p. 17, https://doi.org/10.1007/978-1-4684-8771-8_3 , Google ScholarCrossrefreproduced in Phys. World 3, 33 (August 1990). , Google Scholar2. Two reviews are P. Pearle in Open Systems and Measurement in Relativistic Quantum Field Theory, H. P. Breuer, F. Petruccionne, eds., Springer, Berlin (1999), p. 195 and , Google ScholarCrossref A. Bassi, G. C. Ghirardi, Phys. Rep. 379, 257 (2003). https://doi.org/10.1016/S0370-1573(03)00103-0 , , Google ScholarCrossref, ISI3. R. Feynman, in The Character of Physical Law, MIT Press, Cambridge, MA (1970), p. 171. Google Scholar© 2009 American Institute of Physics.
David Mermin tells us that our “bad habit” of reifying the quantum state “induces people to write books and organize conferences about ‘the quantum measurement problem.’ “ However, a quantum measurement problem does not arise only from an unfortunate perspective on quantum theory. A quantum measurement problem, as close to magic as anything in science, is displayed in quantum-theory-neutral experimental observations that assume only the free choice of the experimenters. In the two-slit experiment, one can choose to demonstrate each object concentrated at a single slit or perform the contradictory demonstration, that each object spread over both slits. Facing this dilemma, George Greenstein and Arthur Zajonc note that “even had quantum theory never been invented, these [two-slit] experiments could have been performed, and we would still find ourselves unable to understand them.” 1 1. G. Greenstein, A. Zajonc, The Quantum Challenge: Modern Research on the Foundations of Quantum Mechanics, 2nd ed., Jones and Bartlett, Sudbury, MA (2006), p. 124. Quantum weirdness is increasingly misappropriated as a way to buttress pseudoscience. It is a responsibility of physicists to combat such misappropriation. (See our letter in Physics Today, November 2006, page 14.)Presenting the intriguing strangeness of quantum mechanics honestly and interestingly by the use of books Mermin might seem to deplore can effectively combat the misuse of the quantum mysteries. Dismissing the measurement problem as merely a bad way of viewing quantum theory abandons a fascinating mystery in physics to the purveyors of pseudoscience.REFERENCESection:ChooseTop of pageREFERENCE <<1. G. Greenstein, A. Zajonc, The Quantum Challenge: Modern Research on the Foundations of Quantum Mechanics, 2nd ed., Jones and Bartlett, Sudbury, MA (2006), p. 124. Google Scholar© 2009 American Institute of Physics.
I am that friend of David Mermin’s “who was enchanted by the revelation that quantum fields were the real stuff that makes up the world.” I plead guilty to reification and offer the following defense.I started out, as I think we all did, with the notion that there is a reality out there and that space and time are part of it—not just “an extremely effective way to represent relations between distinct events.” When I read Arthur Eddington’s The Nature of the Physical World (J. M. Dent & Sons, 1942) in high school, I learned that reality was not what it seemed—that Eddington’s solid writing desk, for example, was mostly empty space. The next step in my understanding of reality came in college when I found that the electromagnetic field offered a more satisfying picture of the world than action at a distance, which even Isaac Newton derided. 1 1. H. Boorse, L. Motz, eds., The World of the Atom, Basic Books, New York (1966), p. 319. When I encountered quantum mechanics, of course, everything became confusion. However, along with David, I was fortunate to attend Julian Schwinger’s courses at Harvard University just after he had perfected his treatment of quantum field theory. 2 2. J. Schwinger, Ann. Phys. 2, 407 (1957). https://doi.org/10.1016/0003-4916(57)90015-5 I sat enthralled throughout the three-year series (1956–59), in which Schwinger developed QFT as a seemingly inevitable consequence of the most basic assumptions.However, I came away with a different understanding of QFT than David’s. I understood that the fields are physical properties of space that are described by field strengths—just as in classical physics, except that in QFT the state of the field at each point is represented by a vector in Hilbert space rather than by a pure number. That use of Hilbert space, which followed naturally from Schwinger’s “measurement algebra,” allows superpositions of values. The operators in Hilbert space, as I understood it, are mathematical tools that describe the evolution of the state vectors, and they are not to be reified.When I saw how QFT resolves the paradoxes of modern physics, it became irresistible. The special relativity paradoxes—for example, Lorentz contraction and time dilation—are a natural result of the way fields behave. 3 3. J. Schwinger wrote a six-part series on the theory of quantized fields: Phys. Rev. 82, 914 (1951); 91, 713 (1953); https://doi.org/10.1103/PhysRev.82.914 91, 728 (1953); 92, 1283 (1953); 93, 615 (1954); 94, 1362 (1954). The spacetime curvature of general relativity, which I could never really visualize, does not exist in QFT; the gravitational field equations are equivalent to spacetime curvature for those who can visualize it, but equivalent is not the same as identical. 4 4. S. Weinberg, Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity, Wiley, New York (1972), pp. vii–147. Finally, the mysterious wave–particle duality of quantum mechanics vanishes; in QFT, reality consists of fields and only fields.Because QFT is so neglected by the public (and by many physicists), I am writing a book that presents it without equations. A draft copy of the work, The Theory That Escaped Einstein, can be found through an internet search. Feedback is appreciated.For those who can’t kick the reification habit, QFT is the way to go. It is the only theory that offers a consistent and visualizable picture of reality. Reifiers of the world, unite! You have nothing to lose but your abstractions.REFERENCESSection:ChooseTop of pageREFERENCES <<1. H. Boorse, L. Motz, eds., The World of the Atom, Basic Books, New York (1966), p. 319. Google Scholar2. J. Schwinger, Ann. Phys. 2, 407 (1957). https://doi.org/10.1016/0003-4916(57)90015-5 , Google ScholarCrossref, ISI3. J. Schwinger wrote a six-part series on the theory of quantized fields: Phys. Rev. 82, 914 (1951); 91, 713 (1953); https://doi.org/10.1103/PhysRev.82.914 , Google ScholarCrossref, ISI 91, 728 (1953); , Google Scholar 92, 1283 (1953); Google Scholar 93, 615 (1954); Google Scholar 94, 1362 (1954). Google Scholar4. S. Weinberg, Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity, Wiley, New York (1972), pp. vii–147. Google Scholar© 2009 American Institute of Physics.
I thoroughly enjoyed David Mermin’s May 2009 Reference Frame. However, definitions of the terms “abstraction” and “reality” are necessary. Unfortunately, that is an extraordinarily difficult task. I offer here the admittedly naive concepts I employed in attempting to understand his essay.Reality is that which can be observed; this is, presumably, what Bertrand Russell meant when he stated that the proof of a concept lies in its comparison with reality. Observations, though, don’t always lead to unique interpretations: Entanglement can be fancifully interpreted as action at a distance, when it is really the result of two particles being produced by a single quantum state that requires that they obey the conservation laws applicable to the particular state.If anything is ever detected, or is prevented from passing between two entangled particles, action at a distance would be confirmed. In the absence of such evidence, I prefer the less exotic explanations.We humans are attracted to fanciful models that are often more exciting than reality; so I agree with Mermin’s basic premise. But I cannot always be confident of distinguishing a real property from a fanciful abstraction. In fact, if pushed, I would have to admit I’m not sure what a real property really is. Possibly Mermin can enlighten me.© 2009 American Institute of Physics.