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Drift 13, Rm. 003 Organized Session | Special Interest Group Physical Sciences
26 Jul 2019 09:00 AM - 11:45 AM (Europe/Amsterdam) Switch to local time
20190726T0900 20190726T1145 Europe/Amsterdam Cosmic Stories: Astrophysics and the Invention of Cosmology in the Early 20th-Century The papers in this session recall the intellectually-challenging context in astronomy and astrophysics at the turn of the 20th century, when a wealth of empirical data became available, giving rise to... Drift 13, Rm. 003 History of Science Society 2019 meeting@hssonline.org

The papers in this session recall the intellectually-challenging context in astronomy and astrophysics at the turn of the 20th century, when a wealth of empirical data became available, giving rise to a host of new, and quite puzzling statistical correlations, the reality of which was often deemed uncertain. Several theorists braved the uncertainties, drawing on the new correlations to elaborate models of stellar dynamics, and of the nature and structure of the universe. Inspired by kinetic gas theory, in 1901 William Thomson (Lord Kelvin) calculated the dimensions of the universe based on star velocities in the vicinity of the Solar System, giving rise to "stargas" models of the universe, pursued from various angles by J. C. Kapteyn, Henri Poincaré, Arthur Eddington, Karl Schwarzschild, James Jeans, C. V. L. Charlier, and Albert Einstein, from 1906 to 1924. Meanwhile, new theories of the electron and the atom enabled astronomers to investigate the physical properties of stars and explain many of the new correlations. Both Eddington and Anton Pannekoek took a pragmatic, inquisitive approach: Eddington, in his investigations on the internal constitution of stars, valued gaining physical insight over mathematical rigor, while Pannekoek focused on precision measurements and laborious numerical models to determine the physical conditions in the outer layers of stars. Together, these four talks, based largely on previously-unexploited archival sources, provide a richer picture of the ground-breaking developments in early 20th-century astrophysics and cosmology.

Organized by Scott Walter
Co-Sponsored by the HSS Physical Sciences Forum and the IUHPST/DHST Commission on the History of Physics

The Great Correlation Era in Astronomy
09:00 AM - 09:30 AM2019/07/26 07:00:00 UTC - 2019/07/26 07:30:00 UTC
Before astrophysics became truly physical in the 1920s, it was typically described as either "photographic" or "spectroscopic," where empirical mapping campaigns made it possible to intercompare the observed properties of the stars. From this effort, many correlations were established including the HR diagram, spectroscopic parallaxes, a mass-luminosity relation and a period-luminosity relation. But what did they mean?, some astronomers asked. Some speculated about what they implied about stellar development, or about the history of the structure and nature of the universe. But what did these correlations really mean, physically? And were they even real? We explore this question and explore how it resulted in the creation of modern astrophysical practice.
Stargas Models of the Universe and the Rise of Statistical Astronomy
09:30 AM - 10:00 AM2019/07/26 07:30:00 UTC - 2019/07/26 08:00:00 UTC
At the turn of the 20th century, William Thomson (Lord Kelvin), inspired by kinetic gas theory, calculated the dimensions of the universe based on stellar velocities in the vicinity of the Solar System, giving rise to "stargas" models of star clusters -- and of the universe -- pursued from 1904 to the early 1920s by J. C. Kapteyn, Henri Poincaré, Arthur Eddington, Karl Schwarzschild, James Jeans, C. V. L. Charlier and Albert Einstein. The attraction of stargas models, and subsequent formation of statistical astronomy as a subfield of astrophysics, is clarified by the correspondence of Kapteyn and Schwarzschild, in particular. Stargas models of the universe, including Kapteyn's island universe, did not stand up well against observations afforded by the big new North-American telescopes, as E. R. Paul pointed out in 1981. However, the demise of stargas cosmological models in the 1920s did not spell the end of stargas models of star and galaxy clusters. On the contrary, the theorems and methods introduced in this context served as the foundation for stellar dynamics in later decades.
Trial and Error in Astronomy: Arthur S. Eddington's Stellar Models
10:15 AM - 10:45 AM2019/07/26 08:15:00 UTC - 2019/07/26 08:45:00 UTC
Arthur S. Eddington (1882-1944) certainly was one of the world’s most famous astronomers during the interwar period. For thirty years he was the director of the Cambridge Observatory and taught astrophysics at Trinity College. From 1916 onwards, he endeavored to develop a series of stellar models and a decade later he published his influential Internal Constitution of the Stars that Henry Norris Russell dared call “a work of art”. Besides the different steps that led Eddington to his famous mass-luminosity relationship in 1924, enlightened by some unpublished correspondence, this paper addresses some original views in terms of methodology. Indeed, Eddington purposely used trial and error, which he considered “as scientific as any other method”, the important point being to obtain physical insight on the problem one intends to tackle, and to keep mathematics “as the tool and not the master in physical research”.
Precision and Exactitude in the Analysis of Stellar Spectra: How Conviction and Circumstance Shaped Anton Pannekoek’s Scientific Persona and Practice
10:45 AM - 11:15 AM2019/07/26 08:45:00 UTC - 2019/07/26 09:15:00 UTC
The astrophysical research of Anton Pannekoek (1873-1960) is characterized by epistemic virtues like precision, diligence, and exactitude, which he valued over expeditiousness or scope. In theoretical research these virtues were present in his development of laborious numerical methods for the fine analysis of stellar spectra, while in observation research, they were evident in the excruciating detail with which he and his students measured the spectra of only a small number of stars. In part, his approach to astrophysics was shaped by the fact that he was an isolated astronomer without an observatory. The early twentieth century saw the founding of large photographic observatories taking on massive broad-scope cataloguing projects. To establish his own niche, Pannekoek decided to focus on the precise measurement of stellar spectra, spending years measuring only a small number of borrowed photographic plates. While Pannekoek’s adherence to precision and exactitude complied with practical constraints, it also reflected his ideas on the role of science in society. A reputed astronomer, Pannekoek was also a noted and influential Marxist theorist. In his socialist and historical writings, he emphasized that science had above all to be beneficial for society – not only by providing technological advances, but especially by exemplifying a way of thinking. From this standpoint, Pannekoek’s projected self-image of an observational astronomer who focused on precision and work ethic over expeditiousness or scope coincided with the general role he envisioned for scientists in society.
Commentary: Cosmic Stories: Astrophysics and the Invention of Cosmology in the Early 20th-Century
11:15 AM - 11:45 AM2019/07/26 09:15:00 UTC - 2019/07/26 09:45:00 UTC