We address the phenomenon of reflection in concave spherical mirror in two contrasting approaches... more We address the phenomenon of reflection in concave spherical mirror in two contrasting approaches to optics. In his Optics (ca.165) Ptolemy applied the cathetus principle as a regulative means for explaining qualitatively effects related to visual perception in concave spherical mirror. By contrast, Della Porta's study of reflection in concave spherical mirror in Bk. 17, Ch. 4 of his Magia naturalis (1589) and De refractione (1593), was based on the assumption that there is a reciprocal relation between reflection in concave spherical mirror and refraction in glass sphere. We juxtapose these two studies and draw several philosophical lessons from the comparison between these two practices with a view to throwing into relief the fundamental differences in their respective conceptions of optics.
In Borrelli A., Hon G., and Zik Y., (editors). Giambattista Della Porta (1535–1615): A Reassessment. Archimedes, Vol. 44, 2017
In Bk. 17, Ch. 4 of Magia Naturalis (1589) Giambattista Della Porta (ca.
1535–1615) reported his... more In Bk. 17, Ch. 4 of Magia Naturalis (1589) Giambattista Della Porta (ca.
1535–1615) reported his experiments on concave spherical mirrors arranged in various setups. Della Porta identified two critical points: (1) the point of inversion (punctum inversionis) in reference to the place where the magnified image is turned upside down and seen blurred, and (2) the point of burning (punctum incensionis) in reference to the place where the reflected rays concentrate and ignite fire. Opticians and practitioners of the time distinguished between the two points but considered them to occupy the same spatial location.
Della Porta inferred from his studies of concave spherical mirrors that the position of the point of inversion and that of the point of burning occupy different spatial locations. He associated the point of inversion with a locus where the image is seen magnified, turned upside down and blurred—a matter of visual perception. He defined the point of burning as a physical, optical position associated with a geometrical point in which the converging rays ignite fire. Consequently, throughout Bk. 17, Della Porta discarded the point of inversion from his optical nomenclature and referred only to the point of burning, the real—so to speak—optical point. In so doing, Della Porta contributed fundamentally towards the technological management of sets of optical elements.
In this paper we follow the experimental practice of Della Porta as presented by the optical demonstrations in Bk. 17, Ch. 4. We discuss the theoretical principles Della Porta developed to clarify whether his claim concerning concave spherical mirror is hypothetical or was it based on an inference from experience. We offer novel insights into the development of the theory of reflection in concave spherical mirrors as it was pursued by Della Porta. He eliminated perceptual considerations from his optics and considered only geometrical-physical aspects. This approach was most useful in the development of the telescope where the critical aspect is not perception but rather ratio of spatial angles.
ABSTRACT The year 2009 marks the 400th anniversary of the publication of one of the most revoluti... more ABSTRACT The year 2009 marks the 400th anniversary of the publication of one of the most revolutionary scientiªc texts ever written. In this book, appropriately entitled, Astronomia nova, Johannes Kepler (1571–1630) developed an astronomical theory which departs fundamentally from the systems of Ptolemy and Copernicus. One of the great innovations of this theory is its dependence on the science of optics. The declared goal of Kepler in his earlier publication, Paralipomena to Witelo whereby The Optical Part of Astronomy is Treated (Ad Vitellionem Paralipomena, quibus astronomiae pars optica traditvr, 1604), was to solve difªculties and expose illusions astronomers face when conducting astronomical observations with optical instruments. To avoid observational errors that had plagued the antiquated mea- suring techniques for calculating the apparent diameter and angular position of the luminaries, Kepler designed a novel device: the ecliptic instrument. In this paper we seek to shed light on the role optical instruments play in Kepler’s scheme: they impose constraints on theory, but at the same time render astronomical knowledge secure. To get a comprehensive grasp of Kepler’s astonishing achievements it is required to widen the approach to his writings and study Kepler not only as a mathematico-physical astronomer, but also as a designer of instruments and a practicing observer.
The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrume... more The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrument has never been disputed and is considered a historical fact. However, the question what was the procedure which Galileo followed is moot, for he did not disclose his research method. On the traditional view, Galileo was guided by experience, more precisely, systematized experience, which was current among northern Italian artisans and men of science. In other words, it was a trial and error procedure—no theory was involved. A scientific analysis of the optical properties of Galileo's first improved spyglass shows that his procedure could not have been an informed extension of the traditional optics of spectacles. We argue that most likely Galileo realized that the objective and the eyepiece form a system and proceeded accordingly.
Scientific knowledge is in constant flux: sometimes the change is fundamental, sometimes it is in... more Scientific knowledge is in constant flux: sometimes the change is fundamental, sometimes it is incremental; despite the important differences between these two kinds of changes, we find consistent features in the way the new knowledge relates to the antecedent state of a discipline. Logically, generating knowledge requires a fixed set of presuppositions, anchored in a given conceptual framework. The practitioner may or may not be aware of all the elements that are involved in the process of generating knowledge but, whether the elements are assumed explicitly or implicitly, they have to be fixed for the production of knowledge to be coherent. In other words, the scientist determines the relevant background and keeps it fixed throughout the episode during which he or she seeks to contribute to some aspect of scientific knowledge. There is thus a variety of background knowledge and, generally, we distinguish between two sets of elements of knowledge, which we call a “baseline” and a “snapshot”. A baseline captures scientific knowledge at a certain time and it is relatively stable for some given duration. The baseline represents the sum of what is, in principle, available to the community of practitioners in the field. Hence, this kind of background knowledge has no nuances and exhibits no preferences, for it is just an inventory of elements. In contrast, a snapshot is personal, that is, it is the result of applying some rules of selection to the baseline, separating the wheat from the chaff as seen in the context of a specific conceptual framework and metaphysical outlook. A snapshot is directly related to a baseline but it is not simply a subset since it includes, in addition to the selected elements, individual assessments of the elements; such assessments may not be found in the standard works of the relevant field in the public domain, for they reflect the idiosyncratic view of a practitioner. Evaluations, which are personal to a large extent, create a tension, or a problem, which the scientist then seeks to address. In sum, the baseline is public and more or less explicit: what all practitioners are expected to know in a given domain. By contrast, the snapshot is unique to the individual scientist and often it is not fully articulated by the practitioner; rather, it is frequently the case that the historian (or philosopher) identifies implicit elements of the snapshot that were taken for granted by the scientist.
It has long been conventional to associate the scientific revolution with Copernicus’s De revolut... more It has long been conventional to associate the scientific revolution with Copernicus’s De revolutionibus (1543). This essay argues in contrast that Kepler’s Astronomia nova (1609) marks the transformation of science, and especially astronomy, from the ancient and medieval heritage to the modern era. However, Kepler’s extraordinary accomplishment has been lost in contradictory historiographies that do not appreciate Kepler’s unifying theological approach to astronomy.
Symmetry is commonly perceived as a concept that expresses bilateral or radial relations, which e... more Symmetry is commonly perceived as a concept that expresses bilateral or radial relations, which effectively describes spatial arrangements that most people think is in some sense innate to the human mind. So, does the concept have a history? Has it evolved? Was there a revolution? The long history of the concept of symmetry began in classical Antiquity as a single concept with a range of applications, expressing proportionality with a specific constraint. In fact, symmetry was used in two different contexts: in mathematics it had the technical meaning of commensurable, while generally it meant suitable or well proportioned. The latter usage involves an aesthetic judgment arrived at by comparison with an ideal in the relevant domain, in an attempt to establish a certain property of the object, e.g., that it is beautiful or that it functions efficiently. We offer historical evidence that, despite the variety of usages in many different domains, there is a conceptual unity underlying the invocation of symmetry in the period from Antiquity to the 1790s which is distinct from the scientific usages of this term that first emerged in France at the end of the 18th century. We examine the trajectory of the concept in the mathematical and scientific disciplines as well as its trajectory in art and architecture. The changes in the meaning of symmetry from Antiquity to the eighteenth century can be explained by appealing to evolution—nobody in that period claimed to be doing anything new. The philosopher Immanuel Kant is probably the first thinker to indicate that something is fundamentally missing in the traditional account. In 1768 he introduced the concept of incongruent counterparts to indicate a reversal of ordering in entities that are equal and similar but cannot be superposed. However, the key figure in revolutionizing the concept of symmetry was the mathematician Adrien-Marie Legendre who, in 1794, claimed to be doing something new. Indeed, by introducing a principle of ordering he revolutionized the concept, and laid the groundwork for its modern usages.
Bacon discussed three different types of laws of nature: (1) particular laws governing one elemen... more Bacon discussed three different types of laws of nature: (1) particular laws governing one element or phenomenon (such as the law of the gravity of water); (2) the laws of the multiplication of species; and, (3) the universal law of nature. Each set of laws has its own explanatory function: (1) the particular laws account for the unique features of individuals and species; (2) the laws of multiplication explain the common features of matter and how individuals affect one another physically; and (3) the law of universal nature regulates these interactions and keep them in balance. Bacon's laws share common features with early modern conception of laws. For example, they can be restated as if/then sentences and cover future events; some support counterfactuals; and all are endowed with explanatory power and free from space-time limitations. When considered together, they form a system, ordered in hierarchical relations. The different levels of laws cover three aspects of Aristotelian causality: formal, efficient, and final. The law of universal nature is a metaphysical axiom, necessary for upholding the very idea of a nature governed by laws. This indicates that Bacon conceived of nature as orderly and predictable; he presented a conception of a lawful nature and showed an understanding of what it takes to be lawful to a degree that had not been seen before.
Given the belief in the universality of Newtonian mechanics, it is hardly surprising that atomic ... more Given the belief in the universality of Newtonian mechanics, it is hardly surprising that atomic structure was compared to that of a planetary system, taken as a model for it. However, Heisenberg eliminated all pictures and models from his new theory. While Sommerfeld, the theoretical physicist, stressed the didactic importance of the defunct theory, Reichenbach, the philosopher of science, argued that a researcher cannot do without visualization, although this visualization is the " outer clothing " of the theory and does not represent its conceptual " skeleton ". The problem underlying Reichenbach's statement may stem from what Born considered the naive assumption that the laws governing the macrocosm and the microcosm are the same. But even Born continued to present the defunct theory as a preliminary step for understanding quantum mechanics, not as a theory of historical interest. The force of the model and its accompanied imagery were apparently too strong to resist.
Dada a crença na universalidade da mecânica newtoniana, não surpreende que a estrutura atómica tenha sido comparada à de um sistema planetário, tomada como seu modelo. Contudo, Heisenberg eliminou qualquer imagem ou modelo da sua nova teoria. Ao passo que Sommerfeld, o físico teórico, salientou a importância didáctica da defunta teoria, Reichenbach, o filósofo da ciência, argumentou que um investigador não pode trabalhar sem visualização, apesar de esta visualização ser a " roupagem " da teoria e não representar o seu " esqueleto " conceptual. O problema subjacente à posição de Reichenbach pode provir do que Born considerava como a suposição ingénua de que as leis que governam o macrocosmo e o microcosmo são as mesmas. Mas mesmo Born continuou a apresentar a defunta teoria como um passo preliminar para compreender a mecânica quântica, e não como uma teoria com interesse histórico. A força do modelo e a imagética associada eram aparentemente irresistíveis.
Contemporary scholars set the Greek conception of an immanent natural order in opposition to the ... more Contemporary scholars set the Greek conception of an immanent natural order in opposition to the seventeenth century mechanistic conception of extrinsic laws imposed upon nature from without. By contrast, we argue that in the process of making the concept of law of nature, forms and laws were coherently used in theories of natural causation. We submit that such a combination can be found in the thirteenth century. The heroes of our claim are Robert Grosseteste who turned the idea of corporeal form into the common feature of matter, and Roger Bacon who described the effects of that common feature. Bacon detached the explanatory principle from matter and rendered it independent and therefore external to natural substances. Our plausibility argument, anchored in close reading of the relevant texts, facilitates a coherent conception of both 'natures' and 'laws'.
The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrume... more The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrument has never been disputed and is considered a historical fact. However, the question what was the procedure which Galileo followed is moot, for he did not disclose his research method. On the traditional view, Galileo was guided by experience, more precisely, systematized experience, which was current among northern Italian artisans and men of science. In other words, it was a trial-and-error procedure—no theory was involved. A scientific analysis of the optical properties of Galileo's first improved spyglass shows that his procedure could not have been an informed extension of the traditional optics of spectacles. We argue that most likely Galileo realized that the objective and the eyepiece form a system and proceeded accordingly.
... National Technical University of Athens Anthony Grafton, Princeton University Trevor Levere, ... more ... National Technical University of Athens Anthony Grafton, Princeton University Trevor Levere, University of Toronto Jesper Lützen, Copenhagen University William Newman, Jürgen Renn, Max-Planck-Institut für Wissenschaftsgeschichte Alex Roland, Duke University Indian ...
The British Journal for the History of Science, 1989
... Studies (1968), 88, pp. 78-81; APD Mourelatos, 'Plato's "Real Astronomy":... more ... Studies (1968), 88, pp. 78-81; APD Mourelatos, 'Plato's "Real Astronomy": Republic 527D-53ID', in JP Anton (ed.) Science and the Sciences In Plato, with an Introduction by JP Anton, New York, 1980, pp. 33-73; I. Mueller, 'Ascending ...
We address the phenomenon of reflection in concave spherical mirror in two contrasting approaches... more We address the phenomenon of reflection in concave spherical mirror in two contrasting approaches to optics. In his Optics (ca.165) Ptolemy applied the cathetus principle as a regulative means for explaining qualitatively effects related to visual perception in concave spherical mirror. By contrast, Della Porta's study of reflection in concave spherical mirror in Bk. 17, Ch. 4 of his Magia naturalis (1589) and De refractione (1593), was based on the assumption that there is a reciprocal relation between reflection in concave spherical mirror and refraction in glass sphere. We juxtapose these two studies and draw several philosophical lessons from the comparison between these two practices with a view to throwing into relief the fundamental differences in their respective conceptions of optics.
In Borrelli A., Hon G., and Zik Y., (editors). Giambattista Della Porta (1535–1615): A Reassessment. Archimedes, Vol. 44, 2017
In Bk. 17, Ch. 4 of Magia Naturalis (1589) Giambattista Della Porta (ca.
1535–1615) reported his... more In Bk. 17, Ch. 4 of Magia Naturalis (1589) Giambattista Della Porta (ca.
1535–1615) reported his experiments on concave spherical mirrors arranged in various setups. Della Porta identified two critical points: (1) the point of inversion (punctum inversionis) in reference to the place where the magnified image is turned upside down and seen blurred, and (2) the point of burning (punctum incensionis) in reference to the place where the reflected rays concentrate and ignite fire. Opticians and practitioners of the time distinguished between the two points but considered them to occupy the same spatial location.
Della Porta inferred from his studies of concave spherical mirrors that the position of the point of inversion and that of the point of burning occupy different spatial locations. He associated the point of inversion with a locus where the image is seen magnified, turned upside down and blurred—a matter of visual perception. He defined the point of burning as a physical, optical position associated with a geometrical point in which the converging rays ignite fire. Consequently, throughout Bk. 17, Della Porta discarded the point of inversion from his optical nomenclature and referred only to the point of burning, the real—so to speak—optical point. In so doing, Della Porta contributed fundamentally towards the technological management of sets of optical elements.
In this paper we follow the experimental practice of Della Porta as presented by the optical demonstrations in Bk. 17, Ch. 4. We discuss the theoretical principles Della Porta developed to clarify whether his claim concerning concave spherical mirror is hypothetical or was it based on an inference from experience. We offer novel insights into the development of the theory of reflection in concave spherical mirrors as it was pursued by Della Porta. He eliminated perceptual considerations from his optics and considered only geometrical-physical aspects. This approach was most useful in the development of the telescope where the critical aspect is not perception but rather ratio of spatial angles.
ABSTRACT The year 2009 marks the 400th anniversary of the publication of one of the most revoluti... more ABSTRACT The year 2009 marks the 400th anniversary of the publication of one of the most revolutionary scientiªc texts ever written. In this book, appropriately entitled, Astronomia nova, Johannes Kepler (1571–1630) developed an astronomical theory which departs fundamentally from the systems of Ptolemy and Copernicus. One of the great innovations of this theory is its dependence on the science of optics. The declared goal of Kepler in his earlier publication, Paralipomena to Witelo whereby The Optical Part of Astronomy is Treated (Ad Vitellionem Paralipomena, quibus astronomiae pars optica traditvr, 1604), was to solve difªculties and expose illusions astronomers face when conducting astronomical observations with optical instruments. To avoid observational errors that had plagued the antiquated mea- suring techniques for calculating the apparent diameter and angular position of the luminaries, Kepler designed a novel device: the ecliptic instrument. In this paper we seek to shed light on the role optical instruments play in Kepler’s scheme: they impose constraints on theory, but at the same time render astronomical knowledge secure. To get a comprehensive grasp of Kepler’s astonishing achievements it is required to widen the approach to his writings and study Kepler not only as a mathematico-physical astronomer, but also as a designer of instruments and a practicing observer.
The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrume... more The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrument has never been disputed and is considered a historical fact. However, the question what was the procedure which Galileo followed is moot, for he did not disclose his research method. On the traditional view, Galileo was guided by experience, more precisely, systematized experience, which was current among northern Italian artisans and men of science. In other words, it was a trial and error procedure—no theory was involved. A scientific analysis of the optical properties of Galileo's first improved spyglass shows that his procedure could not have been an informed extension of the traditional optics of spectacles. We argue that most likely Galileo realized that the objective and the eyepiece form a system and proceeded accordingly.
Scientific knowledge is in constant flux: sometimes the change is fundamental, sometimes it is in... more Scientific knowledge is in constant flux: sometimes the change is fundamental, sometimes it is incremental; despite the important differences between these two kinds of changes, we find consistent features in the way the new knowledge relates to the antecedent state of a discipline. Logically, generating knowledge requires a fixed set of presuppositions, anchored in a given conceptual framework. The practitioner may or may not be aware of all the elements that are involved in the process of generating knowledge but, whether the elements are assumed explicitly or implicitly, they have to be fixed for the production of knowledge to be coherent. In other words, the scientist determines the relevant background and keeps it fixed throughout the episode during which he or she seeks to contribute to some aspect of scientific knowledge. There is thus a variety of background knowledge and, generally, we distinguish between two sets of elements of knowledge, which we call a “baseline” and a “snapshot”. A baseline captures scientific knowledge at a certain time and it is relatively stable for some given duration. The baseline represents the sum of what is, in principle, available to the community of practitioners in the field. Hence, this kind of background knowledge has no nuances and exhibits no preferences, for it is just an inventory of elements. In contrast, a snapshot is personal, that is, it is the result of applying some rules of selection to the baseline, separating the wheat from the chaff as seen in the context of a specific conceptual framework and metaphysical outlook. A snapshot is directly related to a baseline but it is not simply a subset since it includes, in addition to the selected elements, individual assessments of the elements; such assessments may not be found in the standard works of the relevant field in the public domain, for they reflect the idiosyncratic view of a practitioner. Evaluations, which are personal to a large extent, create a tension, or a problem, which the scientist then seeks to address. In sum, the baseline is public and more or less explicit: what all practitioners are expected to know in a given domain. By contrast, the snapshot is unique to the individual scientist and often it is not fully articulated by the practitioner; rather, it is frequently the case that the historian (or philosopher) identifies implicit elements of the snapshot that were taken for granted by the scientist.
It has long been conventional to associate the scientific revolution with Copernicus’s De revolut... more It has long been conventional to associate the scientific revolution with Copernicus’s De revolutionibus (1543). This essay argues in contrast that Kepler’s Astronomia nova (1609) marks the transformation of science, and especially astronomy, from the ancient and medieval heritage to the modern era. However, Kepler’s extraordinary accomplishment has been lost in contradictory historiographies that do not appreciate Kepler’s unifying theological approach to astronomy.
Symmetry is commonly perceived as a concept that expresses bilateral or radial relations, which e... more Symmetry is commonly perceived as a concept that expresses bilateral or radial relations, which effectively describes spatial arrangements that most people think is in some sense innate to the human mind. So, does the concept have a history? Has it evolved? Was there a revolution? The long history of the concept of symmetry began in classical Antiquity as a single concept with a range of applications, expressing proportionality with a specific constraint. In fact, symmetry was used in two different contexts: in mathematics it had the technical meaning of commensurable, while generally it meant suitable or well proportioned. The latter usage involves an aesthetic judgment arrived at by comparison with an ideal in the relevant domain, in an attempt to establish a certain property of the object, e.g., that it is beautiful or that it functions efficiently. We offer historical evidence that, despite the variety of usages in many different domains, there is a conceptual unity underlying the invocation of symmetry in the period from Antiquity to the 1790s which is distinct from the scientific usages of this term that first emerged in France at the end of the 18th century. We examine the trajectory of the concept in the mathematical and scientific disciplines as well as its trajectory in art and architecture. The changes in the meaning of symmetry from Antiquity to the eighteenth century can be explained by appealing to evolution—nobody in that period claimed to be doing anything new. The philosopher Immanuel Kant is probably the first thinker to indicate that something is fundamentally missing in the traditional account. In 1768 he introduced the concept of incongruent counterparts to indicate a reversal of ordering in entities that are equal and similar but cannot be superposed. However, the key figure in revolutionizing the concept of symmetry was the mathematician Adrien-Marie Legendre who, in 1794, claimed to be doing something new. Indeed, by introducing a principle of ordering he revolutionized the concept, and laid the groundwork for its modern usages.
Bacon discussed three different types of laws of nature: (1) particular laws governing one elemen... more Bacon discussed three different types of laws of nature: (1) particular laws governing one element or phenomenon (such as the law of the gravity of water); (2) the laws of the multiplication of species; and, (3) the universal law of nature. Each set of laws has its own explanatory function: (1) the particular laws account for the unique features of individuals and species; (2) the laws of multiplication explain the common features of matter and how individuals affect one another physically; and (3) the law of universal nature regulates these interactions and keep them in balance. Bacon's laws share common features with early modern conception of laws. For example, they can be restated as if/then sentences and cover future events; some support counterfactuals; and all are endowed with explanatory power and free from space-time limitations. When considered together, they form a system, ordered in hierarchical relations. The different levels of laws cover three aspects of Aristotelian causality: formal, efficient, and final. The law of universal nature is a metaphysical axiom, necessary for upholding the very idea of a nature governed by laws. This indicates that Bacon conceived of nature as orderly and predictable; he presented a conception of a lawful nature and showed an understanding of what it takes to be lawful to a degree that had not been seen before.
Given the belief in the universality of Newtonian mechanics, it is hardly surprising that atomic ... more Given the belief in the universality of Newtonian mechanics, it is hardly surprising that atomic structure was compared to that of a planetary system, taken as a model for it. However, Heisenberg eliminated all pictures and models from his new theory. While Sommerfeld, the theoretical physicist, stressed the didactic importance of the defunct theory, Reichenbach, the philosopher of science, argued that a researcher cannot do without visualization, although this visualization is the " outer clothing " of the theory and does not represent its conceptual " skeleton ". The problem underlying Reichenbach's statement may stem from what Born considered the naive assumption that the laws governing the macrocosm and the microcosm are the same. But even Born continued to present the defunct theory as a preliminary step for understanding quantum mechanics, not as a theory of historical interest. The force of the model and its accompanied imagery were apparently too strong to resist.
Dada a crença na universalidade da mecânica newtoniana, não surpreende que a estrutura atómica tenha sido comparada à de um sistema planetário, tomada como seu modelo. Contudo, Heisenberg eliminou qualquer imagem ou modelo da sua nova teoria. Ao passo que Sommerfeld, o físico teórico, salientou a importância didáctica da defunta teoria, Reichenbach, o filósofo da ciência, argumentou que um investigador não pode trabalhar sem visualização, apesar de esta visualização ser a " roupagem " da teoria e não representar o seu " esqueleto " conceptual. O problema subjacente à posição de Reichenbach pode provir do que Born considerava como a suposição ingénua de que as leis que governam o macrocosmo e o microcosmo são as mesmas. Mas mesmo Born continuou a apresentar a defunta teoria como um passo preliminar para compreender a mecânica quântica, e não como uma teoria com interesse histórico. A força do modelo e a imagética associada eram aparentemente irresistíveis.
Contemporary scholars set the Greek conception of an immanent natural order in opposition to the ... more Contemporary scholars set the Greek conception of an immanent natural order in opposition to the seventeenth century mechanistic conception of extrinsic laws imposed upon nature from without. By contrast, we argue that in the process of making the concept of law of nature, forms and laws were coherently used in theories of natural causation. We submit that such a combination can be found in the thirteenth century. The heroes of our claim are Robert Grosseteste who turned the idea of corporeal form into the common feature of matter, and Roger Bacon who described the effects of that common feature. Bacon detached the explanatory principle from matter and rendered it independent and therefore external to natural substances. Our plausibility argument, anchored in close reading of the relevant texts, facilitates a coherent conception of both 'natures' and 'laws'.
The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrume... more The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrument has never been disputed and is considered a historical fact. However, the question what was the procedure which Galileo followed is moot, for he did not disclose his research method. On the traditional view, Galileo was guided by experience, more precisely, systematized experience, which was current among northern Italian artisans and men of science. In other words, it was a trial-and-error procedure—no theory was involved. A scientific analysis of the optical properties of Galileo's first improved spyglass shows that his procedure could not have been an informed extension of the traditional optics of spectacles. We argue that most likely Galileo realized that the objective and the eyepiece form a system and proceeded accordingly.
... National Technical University of Athens Anthony Grafton, Princeton University Trevor Levere, ... more ... National Technical University of Athens Anthony Grafton, Princeton University Trevor Levere, University of Toronto Jesper Lützen, Copenhagen University William Newman, Jürgen Renn, Max-Planck-Institut für Wissenschaftsgeschichte Alex Roland, Duke University Indian ...
The British Journal for the History of Science, 1989
... Studies (1968), 88, pp. 78-81; APD Mourelatos, 'Plato's "Real Astronomy":... more ... Studies (1968), 88, pp. 78-81; APD Mourelatos, 'Plato's "Real Astronomy": Republic 527D-53ID', in JP Anton (ed.) Science and the Sciences In Plato, with an Introduction by JP Anton, New York, 1980, pp. 33-73; I. Mueller, 'Ascending ...
Proceedings of the International Symposium in Hamburg, October 8-12, 2007., 2008
"With contributions by Gregor Schiemann, Claus Peter Ortlieb, John Preston, Giora Hon, Bernard R.... more "With contributions by Gregor Schiemann, Claus Peter Ortlieb, John Preston, Giora Hon, Bernard R. Goldstein, Rudolf Seising, Peter Heering, Karl Heinrich Wiederkehr, Martin Henke, Martin Wegener, Frank Dittmann, Roland Wittje, Jesper Lützen, Alfred Nordmann, Peter Klein, Stefan L. Wolff, Joachim Pelkowski, Frank Linhard, James G. O'Hara, Vitaly G. Gorokhov, Aleksandar Marincic, Zorica Civric, Richard Strom, Wolfgang König, Horst A. Wessel, Oliver Rump, Albrecht Sauer, Zoltán Kolláth, Hans-Joachim Braun, Peter Donhauser, Joachim Goerth, Renate Tobies, Erika Linz.
First of all I would like to thank for the generous support of the Hertz-Symposium by the Deutsche Forschungsgemeinschaft (DFG) and by the Behörde für Wissenschaft und Forschung (BWF) Hamburg. Then I appreciate the help and advice of Roger Stuewer in organising and planning the symposium, which should bring together different scholars interested in Hertz, in his philosophy of science, his achievements in physics and the impact of his discovery of electromagnetic waves, the development of communication technology (beginnings of radio, radar, radio astronomy, electronic music and mobile phone). I am glad that nearly all, who participated during the symposium, have contributed to the book.1 In Hamburg there are some places connected with the life and social impact of Heinrich Hertz: The birthplace (Poststraße 20, D-20354 Hamburg), where a memorial tablet of the „Patriotische Gesellschaft” was fixed October 8, 2007, the house, where he lived during his youth (Magdalenenstraße 3, Hamburg-Rotherbaum), the family grave (Ohlsdorf Cemetery Q25, 1–6), a portrait medaillon in the entrance hall of Hamburg’s Town Hall, a sculpture “airwave” in Eichenpark near Alster shore, made by the jewish artist
Friedrich Wield (1880–1940) in 1931/33. Apart from a Heinrich Hertz street there are three buildings named after Hertz: the Heinrich-Hertz TV tower, the former Heinrich-Hertz-School (“Reform-Realgymnasium”): Architect Albert Erbe, 1908 (Bundesstr. 58,D-20146 Hamburg), and the Heinrich-Hertz-Schule (Grasweg 72–76, D-22303 Hamburg). There were more activities in connection with Hertz’ 150th birthday, especially an
exhibition with the title “Von Hertz zum Handy – Entwicklung der Kommunikationstechnik” was shown in five different places in Hamburg and Wittenberg;2 in addition a catalogue was published in 2007.3 Another event, organised by Gudrun Wolfschmidt,
was meeting of the Arbeitskreis Astronomiegeschichte (Working Group for History of Astronomy) in the Astronomische Gesellschaft, held in the Institute for Theoretical Physics and Astrophysics, Würzburg University, September 23 to 24, 2007, with the topic: “Astronomy in new wavelengths – historical studies”.4
1 In addition a DVD about the symposium is published: Handwerk, Agnes und Harrie Willems: Allein mit der Natur. Heinrich Hertz – Experiment und Theorie. Hamburg 2008. A biography of
Heinrich Hertz is prepared for the IWF Wissen und Medien gGmbH in Göttingen.
2 http://www.hs.uni-hamburg.de/DE/GNT/events/hertz-exh.htm.
3 Wolfschmidt, Gudrun (ed.): Von Hertz zum Handy – Entwicklung der Kommunikationstechnik. Katalog zur Ausstellung zum 150. Geburtstag von Heinrich Hertz (1857–1894). Norderstedt: Books on Demand (Nuncius Hamburgensis, Beiträge zur Geschichte der Naturwissenschaften, Bd. 6) 2007 (360 pages).
4 Short Contributions are published in Astronomische Nachrichten 328 (2007), No. 7.
http://www.hs.uni-hamburg.de/DE/GNT/events/wuerzburg07.htm A book about the meeting, edited by Gudrun Wolfschmidt is in preparation.
http://www.hs.uni-hamburg.de/DE/GNT/research/nuncius.htm#12."
Uploads
Papers by Giora Hon
between reflection in concave spherical mirror and refraction in glass sphere. We juxtapose these two studies and draw several philosophical lessons from the comparison between these two practices with a view to throwing into relief the fundamental differences in their respective conceptions of optics.
1535–1615) reported his experiments on concave spherical mirrors arranged in various setups. Della Porta identified two critical points: (1) the point of inversion (punctum inversionis) in reference to the place where the magnified image is turned upside down and seen blurred, and (2) the point of burning (punctum incensionis) in reference to the place where the reflected rays concentrate and ignite fire. Opticians and practitioners of the time distinguished between the two points but considered them to occupy the same spatial location.
Della Porta inferred from his studies of concave spherical mirrors that the position of the point of inversion and that of the point of burning occupy different spatial locations. He associated the point of inversion with a locus where the image is seen magnified, turned upside down and blurred—a matter of visual perception. He defined the point of burning as a physical, optical position associated with a geometrical point in which the converging rays ignite fire. Consequently, throughout Bk. 17, Della Porta discarded the point of inversion from his optical nomenclature and referred only to the point of burning, the real—so to speak—optical point. In so doing, Della Porta contributed fundamentally towards the technological management of sets of optical elements.
In this paper we follow the experimental practice of Della Porta as presented by the optical demonstrations in Bk. 17, Ch. 4. We discuss the theoretical principles Della Porta developed to clarify whether his claim concerning concave spherical mirror is hypothetical or was it based on an inference from experience. We offer novel insights into the development of the theory of reflection in concave spherical mirrors as it was pursued by Della Porta. He eliminated perceptual considerations from his optics and considered only geometrical-physical aspects. This approach was most useful in the development of the telescope where the critical aspect is not perception but rather ratio of spatial angles.
There is thus a variety of background knowledge and, generally, we distinguish between two sets of elements of knowledge, which we call a “baseline” and a “snapshot”. A baseline captures scientific knowledge at a certain time and it is relatively stable for some given duration. The baseline represents the sum of what is, in principle, available to the community of practitioners in the field. Hence, this kind of background knowledge has no nuances and exhibits no preferences, for it is just an inventory of elements. In contrast, a snapshot is personal, that is, it is the result of applying some rules of selection to the baseline, separating the wheat from the chaff as seen in the context of a specific conceptual framework and metaphysical outlook. A snapshot is directly related to a baseline but it is not simply a subset since it includes, in addition to the selected elements, individual assessments of the elements; such assessments may not be found in the standard works of the relevant field in the public domain, for they reflect the idiosyncratic view of a practitioner. Evaluations, which are personal to a large extent, create a tension, or a problem, which the scientist then seeks to address. In sum, the baseline is public and more or less explicit: what all practitioners are expected to know in a given domain. By contrast, the snapshot is unique to the individual scientist and often it is not fully articulated by the practitioner; rather, it is frequently the case that the historian (or philosopher) identifies implicit elements of the snapshot that were taken for granted by the scientist.
Dada a crença na universalidade da mecânica newtoniana, não surpreende que a estrutura atómica tenha sido comparada à de um sistema planetário, tomada como seu modelo. Contudo, Heisenberg eliminou qualquer imagem ou modelo da sua nova teoria. Ao passo que Sommerfeld, o físico teórico, salientou a importância didáctica da defunta teoria, Reichenbach, o filósofo da ciência, argumentou que um investigador não pode trabalhar sem visualização, apesar de esta visualização ser a " roupagem " da teoria e não representar o seu " esqueleto " conceptual. O problema subjacente à posição de Reichenbach pode provir do que Born considerava como a suposição ingénua de que as leis que governam o macrocosmo e o microcosmo são as mesmas. Mas mesmo Born continuou a apresentar a defunta teoria como um passo preliminar para compreender a mecânica quântica, e não como uma teoria com interesse histórico. A força do modelo e a imagética associada eram aparentemente irresistíveis.
between reflection in concave spherical mirror and refraction in glass sphere. We juxtapose these two studies and draw several philosophical lessons from the comparison between these two practices with a view to throwing into relief the fundamental differences in their respective conceptions of optics.
1535–1615) reported his experiments on concave spherical mirrors arranged in various setups. Della Porta identified two critical points: (1) the point of inversion (punctum inversionis) in reference to the place where the magnified image is turned upside down and seen blurred, and (2) the point of burning (punctum incensionis) in reference to the place where the reflected rays concentrate and ignite fire. Opticians and practitioners of the time distinguished between the two points but considered them to occupy the same spatial location.
Della Porta inferred from his studies of concave spherical mirrors that the position of the point of inversion and that of the point of burning occupy different spatial locations. He associated the point of inversion with a locus where the image is seen magnified, turned upside down and blurred—a matter of visual perception. He defined the point of burning as a physical, optical position associated with a geometrical point in which the converging rays ignite fire. Consequently, throughout Bk. 17, Della Porta discarded the point of inversion from his optical nomenclature and referred only to the point of burning, the real—so to speak—optical point. In so doing, Della Porta contributed fundamentally towards the technological management of sets of optical elements.
In this paper we follow the experimental practice of Della Porta as presented by the optical demonstrations in Bk. 17, Ch. 4. We discuss the theoretical principles Della Porta developed to clarify whether his claim concerning concave spherical mirror is hypothetical or was it based on an inference from experience. We offer novel insights into the development of the theory of reflection in concave spherical mirrors as it was pursued by Della Porta. He eliminated perceptual considerations from his optics and considered only geometrical-physical aspects. This approach was most useful in the development of the telescope where the critical aspect is not perception but rather ratio of spatial angles.
There is thus a variety of background knowledge and, generally, we distinguish between two sets of elements of knowledge, which we call a “baseline” and a “snapshot”. A baseline captures scientific knowledge at a certain time and it is relatively stable for some given duration. The baseline represents the sum of what is, in principle, available to the community of practitioners in the field. Hence, this kind of background knowledge has no nuances and exhibits no preferences, for it is just an inventory of elements. In contrast, a snapshot is personal, that is, it is the result of applying some rules of selection to the baseline, separating the wheat from the chaff as seen in the context of a specific conceptual framework and metaphysical outlook. A snapshot is directly related to a baseline but it is not simply a subset since it includes, in addition to the selected elements, individual assessments of the elements; such assessments may not be found in the standard works of the relevant field in the public domain, for they reflect the idiosyncratic view of a practitioner. Evaluations, which are personal to a large extent, create a tension, or a problem, which the scientist then seeks to address. In sum, the baseline is public and more or less explicit: what all practitioners are expected to know in a given domain. By contrast, the snapshot is unique to the individual scientist and often it is not fully articulated by the practitioner; rather, it is frequently the case that the historian (or philosopher) identifies implicit elements of the snapshot that were taken for granted by the scientist.
Dada a crença na universalidade da mecânica newtoniana, não surpreende que a estrutura atómica tenha sido comparada à de um sistema planetário, tomada como seu modelo. Contudo, Heisenberg eliminou qualquer imagem ou modelo da sua nova teoria. Ao passo que Sommerfeld, o físico teórico, salientou a importância didáctica da defunta teoria, Reichenbach, o filósofo da ciência, argumentou que um investigador não pode trabalhar sem visualização, apesar de esta visualização ser a " roupagem " da teoria e não representar o seu " esqueleto " conceptual. O problema subjacente à posição de Reichenbach pode provir do que Born considerava como a suposição ingénua de que as leis que governam o macrocosmo e o microcosmo são as mesmas. Mas mesmo Born continuou a apresentar a defunta teoria como um passo preliminar para compreender a mecânica quântica, e não como uma teoria com interesse histórico. A força do modelo e a imagética associada eram aparentemente irresistíveis.
First of all I would like to thank for the generous support of the Hertz-Symposium by the Deutsche Forschungsgemeinschaft (DFG) and by the Behörde für Wissenschaft und Forschung (BWF) Hamburg. Then I appreciate the help and advice of Roger Stuewer in organising and planning the symposium, which should bring together different scholars interested in Hertz, in his philosophy of science, his achievements in physics and the impact of his discovery of electromagnetic waves, the development of communication technology (beginnings of radio, radar, radio astronomy, electronic music and mobile phone). I am glad that nearly all, who participated during the symposium, have contributed to the book.1 In Hamburg there are some places connected with the life and social impact of Heinrich Hertz: The birthplace (Poststraße 20, D-20354 Hamburg), where a memorial tablet of the „Patriotische Gesellschaft” was fixed October 8, 2007, the house, where he lived during his youth (Magdalenenstraße 3, Hamburg-Rotherbaum), the family grave (Ohlsdorf Cemetery Q25, 1–6), a portrait medaillon in the entrance hall of Hamburg’s Town Hall, a sculpture “airwave” in Eichenpark near Alster shore, made by the jewish artist
Friedrich Wield (1880–1940) in 1931/33. Apart from a Heinrich Hertz street there are three buildings named after Hertz: the Heinrich-Hertz TV tower, the former Heinrich-Hertz-School (“Reform-Realgymnasium”): Architect Albert Erbe, 1908 (Bundesstr. 58,D-20146 Hamburg), and the Heinrich-Hertz-Schule (Grasweg 72–76, D-22303 Hamburg). There were more activities in connection with Hertz’ 150th birthday, especially an
exhibition with the title “Von Hertz zum Handy – Entwicklung der Kommunikationstechnik” was shown in five different places in Hamburg and Wittenberg;2 in addition a catalogue was published in 2007.3 Another event, organised by Gudrun Wolfschmidt,
was meeting of the Arbeitskreis Astronomiegeschichte (Working Group for History of Astronomy) in the Astronomische Gesellschaft, held in the Institute for Theoretical Physics and Astrophysics, Würzburg University, September 23 to 24, 2007, with the topic: “Astronomy in new wavelengths – historical studies”.4
1 In addition a DVD about the symposium is published: Handwerk, Agnes und Harrie Willems: Allein mit der Natur. Heinrich Hertz – Experiment und Theorie. Hamburg 2008. A biography of
Heinrich Hertz is prepared for the IWF Wissen und Medien gGmbH in Göttingen.
2 http://www.hs.uni-hamburg.de/DE/GNT/events/hertz-exh.htm.
3 Wolfschmidt, Gudrun (ed.): Von Hertz zum Handy – Entwicklung der Kommunikationstechnik. Katalog zur Ausstellung zum 150. Geburtstag von Heinrich Hertz (1857–1894). Norderstedt: Books on Demand (Nuncius Hamburgensis, Beiträge zur Geschichte der Naturwissenschaften, Bd. 6) 2007 (360 pages).
4 Short Contributions are published in Astronomische Nachrichten 328 (2007), No. 7.
http://www.hs.uni-hamburg.de/DE/GNT/events/wuerzburg07.htm
A book about the meeting, edited by Gudrun Wolfschmidt is in preparation.
http://www.hs.uni-hamburg.de/DE/GNT/research/nuncius.htm#12."