Il Saggiatore, Passages in the History of Physics

The laws of physics

2011-12-06T07:48:00.000-08:00

''The concept of physical law, as it is used in modern natural science, does not contain any ideas of command and obedience. Yet it obviously originates in a juridical metaphor. In a well governed state there will be laws which are for the most part observed by the citizens. Lawbreaking will occur comparatively seldom, and will be punished when detected. The more powerful the government and the cleverer the police is, the rarer it will be. Let us suppose now the government to be omnipotent and the police to be omniscient. In this ideal case the behavior of the citizens would completely conform to the demands of the lawgiver and laws would be always observed. With such an ideal state nature was compared in the seventeenth century. The observable recurrent associations of physical events, in which the philosophers and scientists of the period began to be interested, were interpreted as divine commands and were called natural laws. Thus the concept of natural law originated in theological ideas. Later these non-empirical components fell gradually into oblivion. Our historical investigation, therefore, will have to trace the idea of God as a lawgiver to nature and the influence of this idea on the rising natural sciences. Since one is, generally speaking, inclined to consider contemporary ideas as a matter of course and to ascribe them uncritically to thinkers of the past, we shall bring into prominence the differences from modern thinking before the seventeenth century. Finally we shall try to explain sociologically why the concept of physical law was lacking then and why it developed in the period of Descartes, Hooke, Boyle, and Newton.''

In Zilsel, ''The Genesis of the Concept of Physical Law''.
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Deep thinking

2011-11-17T06:22:00.000-08:00

''On matters of physics, I always regarded Stephen [Hawking] as an oracle and just a few words from him could yield insights which would have taken weeks of work on my own. I was therefore particularly lucky to share an office with him since this gave me privileged access to there insights. However, Stephen is only human and not all encounters led to illumination. Once, while sharing an office with him at Caltech, I asked him a question about something which was puzzling me. He thought about it silently for several minutes and I was quite impressed with myself for asking something which Stephen couldn't answer immediately. His eyes then closed and I was even more impressed with myself because Stephen was clearly having to think about it very deeply. Only after ten minutes did it become clear that he had fallen asleep!''

Carr, ''Primordial Black Holes'', in Gibbons et al. (eds), The Future of Theoretical Physics and Cosmology: Celebrating Stephen Hawking's 60th Birthday, p. 258.
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ポール・ディラック

2011-11-03T04:39:00.000-07:00

''Dirac deeply influenced Tomonaga, and through Tomonaga he had a pervasive influence on an entire generation of Japanese physicists. During the summer of 1935, Nishina, Kobayasi, Tamaki, and Tomonaga – the theoretical group of the Nishina Laboratory – 'devoted' themselves to translating Dirac's 'famous textbook of the quantum theory' into Japanese.

We three rented a small villa at Karuizawa, a famous summer resort of Japan where Nishina stayed with his family. As soon as we started work, we found how difficult it was to translate English into Japanese which has a completely different sentence structure. The work of translation was really heavy labour, and sometimes we became so tired that we all became bad humoured and disputes often arose over trifling matters. But we made it a rule to take a rest on Sundays and on finishing every chapter, to make excursions to neighboring hills and meadows. The beautiful landscapes and refreshing air were so effective that we all recovered our good humour and we were able to continue our hard work. We believe that the Japanese edition of Dirac's book has been and will continue to be appreciated by many physics students of our country. (Tomonaga 1976, pp. 466-467.)''

In Schweber, QED and The Men Who Made It: Dyson, Feynman, Schwinger, and Tomonaga, pp. 255-256.
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Making profit from physics

2011-10-16T23:42:00.000-07:00

''Thompson [Lord Kelvin] too was deeply attached to the notion of scientific knowledge or capital which generated compound interest available for reinvestment in intellectual capital or for exploitation in industrial application. Patented inventions represented the latter component in the capitalism of intellectual property, that is, the marketing of the 'materially embodied' products of scientific research to commercial interests.''

In Norton & Wise, Energy and Empire: A Biographical Study of Lord Kelvin, p. 707.
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The mathematization of physics

2011-10-03T00:33:00.000-07:00

''Our starting point will be the publication of Newton's Principia which marks, conceptually, a radical departure from the then dominant tradition of mechanical philosophy. We defend the thesis that by taking the mathematical route to natural philosophy Newton initiated, or at least accelerated, a series of social, epistemological and even ontological consequences which over the course of a century, redefined the legitimate practice of physics. As we will see, these consequences were indirect and often only confusedly perceived by the actors involved but led finally to the state of affairs we now generally take for granted: that physics is mathematical in its formulation. Far from being obvious, this idea was long debated over the 18th and even the first half of the 19th century as more and more domains of physics lent themselves to mathematical formulations.''

In Gringas, ''What Did Mathematics Do to Physics'', p. 8.
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Zel'dovich and Pope John Paul II

2011-09-13T21:13:00.000-07:00

''After approaching Pope John Paul II with an unidentified object concealed beneath his jacket, Zel'dovich produced a book of his collected papers, which he donated to the Pope. 'Thanks' the Pope replied, to which Zel'dovich loudly responded 'Not just 'thanks'! These are fifty years of my work!'. The Pope kept Zel'dovich's collected papers (Zel'dovich, 1985) under his arm during the entire rest of the audience.''

Ruffini, ''The Ergosphere and Dyadosphere of the Kerr Black Hole'', in Wiltshire et al. (eds), The Kerr Spacetime, p. 79.
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The electric force, the very basic

2011-08-27T00:06:00.000-07:00

''Now in order clearly to understand how such attraction takes place, and what those substances may be that so attract other bodies (and in the case of many of these electrical substances, though the bodies influenced by them lean toward them, yet because of the feebleness of the attraction they are not drawn clean up to them, but are easily mode to rise), make yourself a rotating‐needle (electroscope ‐ versorium) of any sort of metal, three or four fingers long, pretty light, and poised on a sharp point after the manner of a magnetic pointer. Bring near to one end of it a piece of amber or a gem, lightly rubbed, polished and shining: at once the instrument revolves. Several objects are seen to attract not only natural objects, but things artificially prepared, or manufactured, or form by mixture. Nor is this a rare property possessed by one object or two (as is commonly supposed), but evidently belongs to a multitude of objects, both simple and compound, e.g., sealing‐wax and other unctuous mixtures.''

In Gilbert, De Magnete, p. 79.
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The magic numbers of the quantum

2011-08-13T23:39:00.000-07:00

''It was in the course of similar investigations that Liveing and Dewar discovered in the spectra of sodium and potasium the existence of two series of lines, one of sharp and one of diffuse lines, and established the existence of homologous series, that is, series of lines of the same type in chemically analogous elements. [...].
Three years later, such an empirical formula, the first to comprise correctly all lines of a spectral series, was published by Johan Jakob Balmer, a schoolteacher in Basel. [...]. He therefore expressed the wavelengths of these lines by the formula [in millimeters]

lambda=h m^2/(m^2-2^2) mm

where h=3645.6 x 10^-7 and m=3, 4, 5, 6. Balmer also predicted the existence of a fifth line with wavelength 3969.65 x 10^-7 mm. Informed by von Hagenbach that this line and other additional lines had indeed been discovered by Huggins, Balmer showed in a second paper that this formula applied to all twelve then known hydrogen lines. He also predicted correctly that in the series which subsequently carried his name, no lines of wavelength longer that 6562 x 10^-7 mm would ever be discovered and that the series could converge at 3645.6 x 10^-7 mm. The agreement between the calculated and the observed values of the wavelength was extremely close in the visible region, but for shorter wavelengths slight systematic discrepancies were evident. In view of these discrepancies Balmer expressed some doubts whether the fault lay with the formula or with the data.''

In Jammer, The Conceptual Development of Quantum Mechanics, pp. 65-66.
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Faraday as mathematician

2010-12-23T05:54:00.000-08:00

''I ought to say that I accept Amperes theory as the best present representation of facts, but that still I hold it with little reserve. This reserve is more a general feeling than any thing founded on distinct objections to it. Remember I am no Mathematician. If I were one and could go into a closer examination of the theory than is at present possible for me I might have no doubts left; but all my mathematics consists in that rough natural portion of geometry which every body has more or less. Hence the reason why I have never put my facts into terms of Amperes theory; and why I cling to the relations of Magnetic & Electric forces as the simplest I can perceive; these again are readily distinguished in practise and hence the most convenient if not the best for an experimentalist to refer to. I wish most sincerely some mathematician would think it worth his while to do that for the facts which I can not do for them.''

In a letter of Faraday to William Whewell (19 September 1835), in James (ed.), The Correspondence of Michael Faraday, Vol. 2, 1832-1840, p. 278.
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Laplace and Bonaparte

2010-12-13T20:26:00.000-08:00

''Laplace and Bonaparte were then serving on a commission together with Lacroix to report on an early mathematical memoir of Biot. Bonaparte never made the personal favorite of Laplace that he did of Monge and Berthollet, but in 1807 and 1808 his sister, Elisa, having been elevated to the rank of princess, took up Madame de Laplace and attached her as lady-in-waiting to her court in Lucca. Their correspondence offers glimpse into the Napoleonic world of fashion. On seizing power, Napoleon named Laplace Minister of the Interior. That ministry had responsibility for most aspects of domestic administration other than finance and police. Laplace lasted six weeks in the government, to be replaced by Bonaparte's brother, Lucien. Napoleon's reminiscence at St. Helena is also famous. Laplace, he said, could never 'get a grasp on any question in its true significance; he sought everywhere for subtleties, had only problematic ideas, and in short carried the spirit of the infinitesimal into administration.''

In Gillespie, Pierre-Simon Laplace 1749-1827: A Life in Exact Science, p. 176.
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The Einstein-Hilbert priority dispute

2010-12-05T05:19:00.000-08:00

''According to the commmonly accepted view, David Hilbert completed the general theory of relativity at least 5 days before Albert Einstein submitted his conclusive paper on this theory on 25 November 1915. Hilbert's article, bearing the date of submission 20 November 1915 but published only on 31 March 1916, presents a generally covariant theory of gravitation, including field equations essentially equivalent to those in Einstein's paper. A close analysis of archival material reveals that Hilbert did not anticipate Einstein. The first set of proofs of Hilbert's paper shows that the theory he originally submitted is not generally covariant and does not include the explicit form of the field equations of general relativity.''

In Corry, Renn, and Stachel, “Belated Decisions in the Einstein-Hilbert Dispute”.

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The birth of astrophysics

2010-11-23T21:23:00.000-08:00

''The latter part of the nineteenth century ushered in two new technologies – photography and spectroscopy. For the first time since humans began to observe the heavens, astronomers could study the motions and physics of stars. The spectroscope allowed astronomers to study the stars' chemical composition and their velocities in the line of sight. Photography provided permanent recording of images that astronomers could measure and analyze in detail. These dramatic changes marked the beginnings of a shift away from the older tradition of positional astronomy toward study of the physics of celestial objects. A new field of research – astrophysics – was born.''

In Crelinstein, Einstein's Jury, pp. 9-10.
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Planck and the Quantum

2010-11-13T06:25:00.000-08:00

''What did Planck do in 1900? Conventional wisdom holds that he quantized harmonic oscillators (or resonators, to use his term) in equilibrium with electromagnetic radiation in a cavity, at some fixed temperature. But physicists interested in the history of their discipline have learned to beware of such conventional wisdom, with good reason. If we turn to the historians for guidance, however, we find little consensus. To be sure, most would agree that the unqualified statement that ‘Planck quantized the oscillators’ can be misleading; on any interpretation, Planck’s understanding of this phrase would have been quite different from our own. Nevertheless, many historians, following the lead of Martin J. Klein, do assert that, however tentatively and uncertainly, Planck – with his finite ‘energy elements’ – did introduce something very new into physics in 1900, and almost certainly knew that he had done so. This situation changed in 1978 with the publication of Thomas S. Kuhn’s Black‐Body Theory and the Quantum Discontinuity. Kuhn gave a highly detailed account of Planck’s work and the initial reaction to it. But in the process, he argued that Planck could not possibly have intended such a far‐reaching step. In Kuhn’s words: My point is not that Planck doubted the reality of quantization or that he regarded it as a formality to be eliminated during the further development of his theory. Rather, I am claiming that the concept of restricted resonator energy played no role in his thought .

[…]

In Kuhn's scenario, the prospect of discontinuous energies did not appear until 1905 and 1906, in the work of the young and little‐known physicists Paul Ehrenfest and Albert Einstein. And even then, according to Kuhn, Planck did not take the idea seriously until 1908. Another historian of physics, Olivier Darrigol, has reached similar conclusions, though in part for different reasons, on the basis of his own detailed analysis of Planck’s work. Others have maintained the older view. And from the standpoint of Allan Needell, who also has written extensively on Planck, even to put the issue in these terms is to ask the wrong question: Our goal should be to understand Planck on his own terms, rather than focus too exclusively on a question that would have had little meaning in 1900.

All of these works have led to a much more detailed understanding of Planck, and even to a considerable measure of agreement. Nevertheless, on the central question – how did Planck think about his derivation in 1900? – no consensus has emerged.''

In Gearhart, “Planck, the Quantum, and the Historians,” pp. 171-173.
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The fifth dimension

2010-11-03T07:26:00.000-07:00

''At the end of the summer we went to Sweden to visit my mother before going back to Denmark, where Bohr had obtained a fellowship permitting me to stay in Copenhagen during a leave of absence from Michigan. However, due to my getting seriously ill — an infectious hepatitis — we had to stay in Sweden for a year, arriving in Copenhagen only at the beginning of March 1926. During that half year, when so much happened in physics (Heisenberg’s breakthrough in quantum mechanics, Goudsmit’s and Uhlenbeck’s paper on electron spin, Pauli’s matrix theory of the hydrogen atom, to mention the most important ones), I had hardly done any work on reading. But a few weeks before we went to Copenhagen, during a recreation trip, I had written out the summer’s work on five‐dimensional theory, leaving my quantal speculations for work in Copenhagen. As already mentioned, I started there with the simplest kind of wave equations and tried to work out the stationary states of the harmonic oscillator, when Schrodinger’s first wave mechanical paper appeared.

When Pauli came to Copenhagen some weeks later, I showed him my manuscript on five‐dimensional theory and after reading it he told me that Kaluza some years before had published a similar idea in a paper I had missed. So I looked it up but — as with de Broglie’s thesis, which Bohr had shown me in the summer of 1925 — I read it rather carelessly but quoted both, of course, in the paper I then wrote in a spirit of resignation.''

In Klein, “From My Life of Physics,” in Bethe et al., From a Life of Physics, pp. 77-78.
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The curious history of Stokes' theorem

2010-10-29T01:44:00.000-07:00

''The first statement of the Theorem appears as a postscript to a letter, dated July 2, 1850, from Sir William Thomson (Lord Kelvin) to Stokes. It appeared publicly as question 8 on the Smith's Prize Examination for 1854. This competitive examination, which was taken annually by the best mathematics students at Cambridge University, was set from 1849 to 1882 by Professor Stokes; by the time of his death the result was known universally as Stokes' Theorem. At least three proofs were given by his contemporaries: Thomson published one, another appeared in Thomson and Tait's Treatise on Natural Philosophy, and Maxwell provided another in Electricity and Magnetism. Since this time the name of Stokes has been applied to much more general results, which have figured so prominently in the development of certain parts of mathematics that Stokes' Theorem may be considered a case study in the value of generalization.''

In Spivak, Calculus on Manifolds, p. viii.
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Boltzmann’s physics textbooks

2010-10-23T06:41:00.000-07:00

''Experimental physicists, Boltzmann explained, also had their methods of research, but these were simpler than the theorists', simpler because of the 'continously progressive' nature of experimental work. Theorists, unlike experimentalists, never seemed to settle their disputes, especially as their methods developed discontinously, similarly to styles in art and literature. They viewed their preferred methods 'very subjectively,' through their 'own spectacles.' But theorists, in their disputes, had recourse that experiemntalists did not have, or did not need; it was to publish books, which were generally based upon lectures, that covered the whole of their science, illuminating it from the perspective of their preferred methods. Boltzmann's published lectures on theoretical physics--covering his favorite parts of it, Maxwell's electromagnetic theory, gas theory, and analytical mechanics--were not syntheses of authoritative writings in the field but his version of theoretical physics.''

In McCormmach and Jungnickel, Intellectual Mastery of Nature 2, p. 189.
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Full concentration

2010-10-23T06:33:00.000-07:00

''By the end of 1676, as absorbed in theology and alchemy as he was distracted by correspondence and criticism on optics and mathematics, Newton had virtually cut himself off from the scientific community. Oldenburg died in September 1677, not having heard from Newton for more than half a year. Newton terminated his exchange with Collins by the blunt expedient for not writing. It took him another year to conclude the correspondence on optics, but by the middle of 1678, he succeeded. As nearly as he could, he had reversed the policy of public communication that he began with his letter to Collins in 1670 and retreat to the quiet of his academic sanctuary. He did not emerge for nearly a decade.''

In Westfall, The Life of Isaac Newton, p. 133.
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Ortega y Gasset meets Sr. Einstein

2010-10-23T06:14:00.000-07:00

''On an excursion to Todelo in 1923, Einstein asked Ortega y Gasset how an abstract idea like relativity could be of interest to the masses. Ortega thought the mass appeal had to do with the conjunction of a new cosmological theory with the post-World War I loss of faith in European society: 'In such a circumstance there appeared your work, in which laws are promulgated for the stars, which obey them. The human masses have always perceived astronomical phenomena as religious. In them, science is conjoined with mythology and the scientific genius who masters them acquires a magical halo. You, Sr. Einstein, are the new magus, the confidant of the stars.'''

In Glick, ''Cultural Issues and Relativity,'' in The Comparative Reception of Relativity, pp. 392‐393.
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The dream of the physicist and the mathematician

2009-08-30T13:29:00.000-07:00

''Once upon a time a methodologist of science had a nightmare. He dreamt that some physicists, called 'quantum field theorists,' used an approximation scheme, some of the terms of which were infinite. But the quantum field theorists just threw out the infinite terms, kept the remaining finite expressions, and, to add methodological insult to mathematical injury, thereby obtained the best agreement between theory and experiment that existed anywhere in science. As the reader knows, the methodologist woke up to find that his dream was true.''

In Teller, “Infinite Renormalization,” p. 238.
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Maxwell and the experimental proof

2009-08-13T17:21:00.000-07:00

"After the publication of 'On physical lines of force,' Maxwell's agenda included the experimental verification of three predictions of his theory. He planned to renew his attempts at detecting gyromagnetic effects. He envisioned precise measurements of the inductive capacity ε of various transparent substances in order to verify the theoretical relation with the optical index (ε = n^2). Most importantly, he intended to verify the identity of the velocity of light with the ratio of absolute electromagnetic and electrostatic charge units by improving on Weber and Kohlrausch's measurement. His enrollment in the British project for electric standards eased this task. In 1864 he imagined an arrangement based on the direct comparison between an electrodynamic and an electrostatic force. Four year laters [sic] he published the results of a more sophisticated experiment based on the same principle.

Considering that the electromagnetic derivation of the velocity of light was his most important result, Maxwell tried to 'clear the electromagnetic theory of light of all unwarranted assumptions.' The velocity of light could not possibly depend on the shape of vortices or on their kind of elasticity. In 1864 Maxwell managed to reformulate his theory without any specific mechanism and to describe wave propagation in purely electromagnetic terms."

In Darrigol, Electrodynamics from Ampère to Einstein, pp. 154-155.
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Pauli's opinion of various physicists

2009-08-12T19:03:00.000-07:00

''I related to Feynman other anecdotes about physicists. Some of these were Pauli stories. I told him what I had learned from Pauli when I asked him about his opinion of various physicists. Feynman especially enjoyed the following remarks of Pauli. About Oppenheimer, Pauli had said: 'He always acts like the caricature of God in action!' About Hermann Weyl: 'One must first penetrate his façade [literally 'makeup', Schminke in German] in order to understand his thoughts.' About Leon Rosenfeld: 'He is the choirboy of the Pope [Niels Bohr]!' About Freeman Dyson, which I had heard from Telegdi: 'Everyone wants to learn something from me; no one wants to teach me anything. I had hoped Dyson would do it, but he's only a mathematician!' By now, Feynman was becoming quite eager: 'Did you ask Pauli about me?' I said, 'Yes.' 'Well, what did he say?' I replied, 'When I asked Pauli what he thought of you, he was amused, and replied, "Oh, Feynman, that Feynman, he talks like a gangster!"' This story made Feynman's day; nothing could have pleased him more.''

In Mehra, The Beat of a Different Drum, p. xxix.
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