Tag Archives: History and Philosophy of Physics

Gravitational Machines [CL]

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http://arxiv.org/abs/2305.10470


A gravitational machine is defined as an arrangement of gravitating masses from which useful energy can be extracted. It is shown that such machines may exist if the masses are of normal astronomical size. A simple example of a gravitational machine, consisting of a double star with smaller masses orbiting around it, is described. It is shown that an efficient gravitational machine will also be an emitter of gravitational radiation. The emitted radiation sets a limit on the possible performance of gravitational machines, and also provides us with a possible means for detecting such machines if they exist.

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F. Dyson
Fri, 19 May 23
34/46

Comments: 4 pages, one figure

Abnormal light signals and the underdetermination of theory by evidence in astrophysics [CL]

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http://arxiv.org/abs/2305.08666


We investigate the propagation of certain non-plane wave solutions to Maxwell’s equations in both flat and curved spacetimes. We find that the effective signal velocity associated to such solutions need not be $c$ and that the signal need not propagate along null geodesics; indeed, more than this, we find that the information encoded in the signals associated with such solutions can be substantially non-local. Having established these results, we then turn to their conceptual-philosophical-foundational significance — which, in brief, we take to be the following: (i) one should not assume that all electromagnetic waves generated in the cosmos are localised plane wave packages; thus, (ii) one cannot assume that signals reaching us from the cosmos arrive with a particular velocity (namely, $c$), and that such signals encode local information regarding their sources; therefore (iii) astrophysicists and cosmologists should be wary about making such assumptions in their inferences from obtained data — for to do so may lead to incorrect inferences regarding the nature of our universe.

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F. Asenjo, S. Hojman, N. Linnemann, et. al.
Tue, 16 May 23
42/83

Comments: 16 pages, 4 figures, critical feedback welcome

DT fusion through the $^5$He $3/2+$ "Bretscher state" accounts for $\ge 25\%$ of our existence via nucleosynthesis and for the possibility of fusion energy [CL]

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http://arxiv.org/abs/2305.00647


In big bang nucleosynthesis (BBN), the deuterium-tritium (DT) fusion reaction, D(T,n)$\alpha$, enhanced by the 3/2$^+$ resonance, is responsible for 99% of primordial $^4$He. This has been known for decades and has been well documented in the scientific literature. However, following the tradition adopted by authors of learned articles, it was stated in a matter-of-fact manner and not emphasized; for most people, it has remained unknown. This helium became a source for the subsequent creation of $\geq$25\% of the carbon and other heavier elements and, thus, a substantial fraction of our human bodies. (To be more precise than $\geq$25\% will require future simulation studies on stellar nucleosynthesis.)
Also, without this resonance, controlled fusion energy would be beyond reach. For example, for inertial confinement fusion (ICF), laser energy delivery for the National Ignition Facility (NIF) would have to be approximately 70 times larger for ignition.
Because the resonance enhances the DT fusion cross section a hundredfold, we propose that the 3/2$^+$ $^5$He excited state be referred to as the “Bretscher state” in honor of the Manhattan Project scientist who discovered it, in analogy with the well-known 7.6 MeV “Hoyle state” in $^{12}$C that allows for the resonant 3$\alpha$ formation.

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M. Chadwick, M. Paris and B. Haines
Tue, 2 May 23
4/57

Comments: 4 pages, 4 figures

On Galileo's self-portrait Mentioned by Thomas Salusbury [IMA]

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http://arxiv.org/abs/2304.12320


An intriguing reference to the existence of a self-portrait by Galileo Galilei is contained in the biography of the scientist by Thomas Salusbury dated ca. 1665, of which only one incomplete and inaccessible copy exists. Galileo grew up in a Renaissance atmosphere, acquiring an artistic touch. He was a musician, a writer and also a painter, as reported by Viviani and documented by his watercolours of the Moon and drawings of solar spots. Recently a new portrait with a remarkable similarity to the portraits of Galileo Galilei by Santi di Tito (1601), Domenico Tintoretto (ca. 1604), and Furini (ca. 1612) has been found and examined using sophisticated face recognition techniques. If the identity could be confirmed, other elements, such as the young age of Galileo or the seam in the canvas revealed by infrared and X-ray analysis, may suggest a possible link with the self-portrait mentioned by Salusbury.

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P. Molaro
Wed, 26 Apr 23
29/62

Comments: 10 pages, 3 figures, Conference INSAP IX London

Annotated bibliography: Philosophy of Astrophysics [CL]

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http://arxiv.org/abs/2304.10067


The following annotated bibliography contains a reasonably complete survey of contemporary work in the philosophy of astrophysics. Spanning approximately forty years from the early 1980s to the present day, the bibliography should help researchers entering the field to acquaint themselves with its major texts, while providing an opportunity for philosophers already working on astrophysics to expand their knowledge base and engage with unfamiliar material.

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C. Yetman
Fri, 21 Apr 23
59/60

Comments: 28 pages, 79 entries, forthcoming 2023

The Next Generation Event Horizon Telescope Collaboration: History, Philosophy, and Culture [CL]

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http://arxiv.org/abs/2304.02463


This white paper outlines the plans of the History Philosophy Culture Working Group of the Next Generation Event Horizon Telescope Collaboration.

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P. Galison, J. Doboszewski, J. Elder, et. al.
Thu, 6 Apr 23
3/76

Comments: 23 pages, 1 figure

La inserción de la Astronomía Cultural en la educación formal: fundamentos y propósitos [CL]

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http://arxiv.org/abs/2304.01113


There are vast educational research works that highlight the serious difficulties that students present in learning astronomical subjects, as well as the prevalence of a traditional education distanced from the observational and experiential, thus accentuating the difficulties detected. We argue that progressive teaching with a topocentric and contextualized approach would favor the motivation of the students, the construction of a more real view of current science and a more active role in the learning process. Cultural Astronomy (CA) is an academic discipline that seeks to understand the multiple ways in which societies relate to celestial objects and phenomena. For this reason, we consider that it would be a powerful resource for teaching, since it provides tools for contextualization and allows working with sky experiences linked to “naked eye astronomy”, which requires little or no instruments. It should be noted that CA involves aspects of archaeoastronomy, ethnoastronomy and the history of astronomy, thus offering multiple dimensions to take into account. The present work seeks to base the incorporation of CA studies for astronomy teaching in secondary and tertiary education.

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J. Bastero, F. Karaseur, S. Garofalo, et. al.
Tue, 4 Apr 23
23/111

Comments: Article in Spanish. Published version available at this http URL

Nuevas estrategias de enseñanza: unidades didácticas basadas en temas de la Astronomía Cultural [CL]

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http://arxiv.org/abs/2304.01131


One of the main difficulties that students have in learning astronomy topics is that they fail to relate theoretical information with what they experience in the world around them. The construction by students of a conceptual framework in accordance with the astronomical scientific model demands changes in the current teaching approach. Within this framework, Cultural Astronomy (CA) is a discipline that we can use to rethink new didactic strategies. This paper presents two contextualized proposals from CA. In the first one, the teaching of space and time concepts is approached through traditional examples of orientation by the stars and the use of the calendar, using the case of historical ocean navigation without advanced instruments already highlighted in ethnoastronomical studies. In the second, these concepts are worked on from a case study, this time archaeoastronomical: the monumental horizon calendar of the Chankillo archaeological site, and then continue with the local identification of horizon markers that allow students to build their own calendars. The aim is to illustrate ways of introducing CA elements in didactic units that have as one of their main objectives that the students manage to establish correspondences between constructions of the micro to the mega-space that surrounds them.

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F. Karaseur, J. Bastero, S. Garofalo, et. al.
Tue, 4 Apr 23
86/111

Comments: Article in Spanish. Published version available at this http URL

Resurfaced 1964 VRT video interview of Georges Lemaître [CL]

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http://arxiv.org/abs/2301.07198


On December 31 2022, the Vlaamse Radio- en Televisieomroeporganisatie (VRT), the national public-service broadcaster for the Flemish Community of Belgium, recovered a video recording of a 1964 interview of Georges Lema\^itre. Up until now, that footage was thought to have been lost. This footage represents a unique insight into the views of the physicist often coined as the “father of the Big Bang”. The interview was conducted in French and is available online with Flemish subtitles. In an effort to make this treasure broadly available, we provide in this paper some brief context, an English translation of the interview as well as the French transcript for reference.

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S. Gontcho, J. Eluo and P. Gabor
Thu, 19 Jan 23
56/100

Comments: VRT article linking the recovered footage: this https URL

Roger of Hereford: the twelfth-century astronomer who put Hereford on the map, literally [CL]

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http://arxiv.org/abs/2301.06610


By the twelfth century, northern European scholars gradually embraced Arabic innovations in science and technology. England naturally developed into a significant centre of the new learning in western Europe. Hereford, and specifically its cathedral school, played a particularly important role in the transition of English scholarship to the new learning. Hereford cathedral developed into a focal point for high-level scholarship, attracting numerous scholars from across the continent. Roger of Hereford stands out among his peers as an enlightened scholar who made more practical use than most of the full astronomical and astrological knowledge base available in England at the time. A significant body of recent scholarship focuses on twelfth-century ecclesiastical developments, including those relating to Roger of Hereford’s Computus. However, much less scholarly emphasis is placed on Roger’s astronomical calculations, particularly those which allowed him to establish an important reference meridian at Hereford. Those aspects are the focus of this paper.

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R. Grijs
Wed, 18 Jan 23
79/133

Comments: 17 pages, 5 figures; The Local Historian, in press (April 2023 issue; note that the version of record will have B/W figures)

Swampland Revisited [CL]

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http://arxiv.org/abs/2301.03464


The transcendental expectation of string theory is that the nature of the fundamental forces, particle spectra and masses, together with coupling constants, is uniquely determined by mathematical and logical consistency, non-empirically, that is by pure reason. However pluralism triumphed with the explosive emergence of the multiverse. String theorists have extended a long-sought dream (their unique and final theory) to a landscape or a happy caparnaum. Proponents of string theory try to qualify their arguments via swampland conjectures while cosmologists retreat to their telescopes. We review the current status of the string theory swampland.

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M. Cass\e’ and J. Silk
Tue, 10 Jan 23
70/93

Comments: N/A

Beyond the Born rule in quantum gravity [CL]

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http://arxiv.org/abs/2212.12175


We have recently developed a new understanding of probability in quantum gravity. In this paper we provide an overview of this new approach and its implications. Adopting the de Broglie-Bohm pilot-wave formulation of quantum physics, we argue that there is no Born rule at the fundamental level of quantum gravity with a non-normalisable Wheeler-DeWitt wave functional $\Psi$. Instead the universe is in a perpetual state of quantum nonequilibrium with a probability density $P\neq\left\vert \Psi\right\vert ^{2}$. Dynamical relaxation to the Born rule can occur only after the early universe has emerged into a semiclassical or Schr\”{o}dinger approximation, with a time-dependent and normalisable wave functional $\psi$, for non-gravitational systems on a classical spacetime background. In that regime the probability density $\rho$ can relax towards $\left\vert \psi\right\vert ^{2}$ (on a coarse-grained level). Thus the pilot-wave theory of gravitation supports the hypothesis of primordial quantum nonequilibrium, with relaxation to the Born rule taking place soon after the big bang. We also show that quantum-gravitational corrections to the Schr\”{o}dinger approximation allow quantum nonequilibrium $\rho\neq\left\vert \psi\right\vert ^{2}$ to be created from a prior equilibrium ($\rho=\left\vert \psi\right\vert ^{2}$) state. Such effects are very tiny and difficult to observe in practice.

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A. Valentini
Mon, 26 Dec 22
12/39

Comments: 39 pages. For special issue of Foundations of Physics, ‘Pilot-wave and beyond: Louis de Broglie and David Bohm’s quest for a quantum ontology’, ed. A. Drezet

Neutron Star versus Neutral Star: On the 90th anniversary of Landau's publication in astrophysics [CL]

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http://arxiv.org/abs/2212.10887


In the late age of developing quantum mechanics, Lev Landau, one of the distinguished players, made great efforts to understand the nature of matter, even stellar matter, by applying the quantum theory. Ninety years ago, he published his idea of “neutron” star, which burst upon him during his visit over Europe in the previous year. The key point that motivated Landau to write the paper is to make a state with lower energy for “gigantic nucleus”, avoiding extremely high kinematic energy of electron gas due to the new Fermi-Dirac statistics focused hotly on at that time. Landau had no alternative but to neutronize/neutralize by “combining a proton and an electron”, as electron and proton were supposed to be elementary before the discovery of neutron. However, our understanding of the Nature has fundamentally improved today, and another way (i.e., strangeonization) could also embody neutralization and thus a low-energy state that Landau had in mind, which could further make unprecedented opportunities in this multi-messenger era of astronomy. Strangeon matter in “old” physics may impact dramatically on today’s physics, from compact stars initiated by Landau, to cosmic rays and dark matter. In this essay, we are making briefly the origin and development of neutron star concept to reform radically, to remember Landau’s substantial contribution in astrophysics and to recall those peculiar memories.

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R. Xu
Thu, 22 Dec 22
11/59

Comments: A contribition to IWARA2022

Contemporary Philosophical Perspectives on the Cosmological Constant [CL]

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http://arxiv.org/abs/2212.04335


The (re)introduction of $\Lambda$ into cosmology has spurred debates that touch on central questions in philosophy of science, as well as the foundations of general relativity and particle physics. We provide a systematic assessment of the often implicit philosophical assumptions guiding the methodology of precision cosmology in relation to dark energy. We start by briefly introducing a recent account of scientific progress in terms of risky and constrained lines of inquiry. This allows us to contrast aspects of $\Lambda$ that make it relevantly different from other theoretical entities in science, such as its remoteness from direct observation or manipulability. We lay out a classification for possible ways to explain apparent accelerated expansion but conclude that these conceptually clear distinctions may blur heavily in practice. Finally, we consider the important role played in cosmology by critical tests of background assumptions, approximation techniques, and core principles, arguing that the weak anthropic principle fits into this category. We argue that some core typicality assumptions — like the Copernican principle and the cosmological principle — are necessary though not provable, while others — like the strong anthropic principle and appeals to naturalness or probability in the multiverse — are not similarly justifiable.

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A. Koberinski, B. Falck and C. Smeenk
Fri, 9 Dec 22
23/75

Comments: Forthcoming in a special issue of Universe

Sunspot periodicity [SSA]

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http://arxiv.org/abs/2212.03249


The Schwabe (~11 yr) value for the annual sunspot number is sometimes uncritically applied to other measures of solar activity, direct and indirect, including the 10.7 cm radio flux, the inflow of galactic cosmic rays, solar flare frequency, terrestrial weather, and components of space climate, with the risk of a resulting loss of information. The ruling (Babcock) hypothesis and its derivatives link the sunspot cycle to dynamo processes mediated by differential solar rotation, but despite 60 years of observation and analysis the ~11 yr periodicity remains difficult to model; the possible contribution of planetary dynamics is undergoing a revival. The various solar sequences that genuinely display an ~11 yr cycle stand to benefit from an understanding of its periodicity that goes beyond statistical kinship. The outcome could ironically prompt the demotion of sunspots from their dominant historical role in favour of other possible indicators of solar cyclicity, such as the solar wind flux and its isotopic signatures, even if they are less accessible.

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C. Vita-Finzi
Thu, 8 Dec 22
10/63

Comments: 28 pages

Centenary of Alexander Friedmann's Prediction of the Universe Expansion and the Quantum Vacuum [CL]

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http://arxiv.org/abs/2211.17101


We review the main scientific pictures of the universe developed from ancient times to Albert Einstein and underline that all of them treated the universe as a stationary system with unchanged physical properties. In contrast to this, 100 years ago Alexander Friedmann predicted that the universe expands starting from the point of infinitely large energy density. We briefly discuss the physical meaning of this prediction and its experimental confirmation consisting of the discovery of redshift in the spectra of remote galaxies and relic radiation. After mentioning the horizon problem in the theory of the hot universe, the inflationary model is considered in connection with the concept of quantum vacuum as an alternative to the inflaton field. The accelerated expansion of the universe is discussed as powered by the cosmological constant originating from the quantum vacuum. The conclusion is made that since Alexander Friedmann’s prediction of the universe expansion radically altered our picture of the world in comparison with the previous epochs, his name should be put on a par with the names of Ptolemy and Copernicus.

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G. Klimchitskaya and V. Mostepanenko
Thu, 1 Dec 22
63/85

Comments: 16 pages, 1 figure

Archaeoastronomical study on the north-central coast of Peru [CL]

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http://arxiv.org/abs/2211.05901


The Caral civilization developed on the north-central coast of Peru and had an occupation period between 2870 and 1970 years BC. The first studies carried out in the field of archaeoastronomy showed evidence of possible astronomical orientations in some buildings of its capital city, the Ciudad Sagrada de Caral. However, methodological issues cast doubt on these conclusions. A recent study carried out a more general statistical analysis, which covered a total of 55 architectural structures distributed in ten urban settlements that were part of this civilization, thus managing to identify topographic and astronomical orientation patterns. Based on this evidence, we propose to carry out a new study focused on the capital city, with the objective of analyzing the orientation pattern of the city, placing emphasis on the analysis of the most important religious and administrative structures in order to determine their functionality and their possible links with relevant astronomical objects. The study will include field work to measure the various structures and the subsequent statistical analysis of the data, using declination histograms, density functions and probability tests.

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J. Ricra and A. Gangui
Mon, 14 Nov 22
9/69

Comments: Article in Spanish. Paper presented at The 63rd meeting of the Argentine Astronomical Society, held in Cordoba, Argentina, 25-29 October 2021

Explanatory Depth in Primordial Cosmology: A Comparative Study of Inflationary and Bouncing Paradigms [CL]

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http://arxiv.org/abs/2210.14625


We develop and apply a multi-dimensional conception of explanatory depth towards a comparative analysis of inflationary and bouncing paradigms in primordial cosmology. Our analysis builds on earlier work due to Azhar and Loeb (2021) that establishes initial condition fine-tuning as a dimension of explanatory depth relevant to debates in contemporary cosmology. We propose dynamical fine-tuning and autonomy as two further dimensions of depth in the context of problems with instability and trans-Planckian modes that afflict bouncing and inflationary approaches respectively. In the context of the latter issue, we argue that the recently formulated trans-Planckian censorship conjecture leads to a trade-off for inflationary models between dynamical fine-tuning and autonomy. We conclude with the suggestion that explanatory preference with regard to the different dimensions of depth is best understood in terms of differing attitudes towards heuristics for future model building.

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W. Wolf and K. Thebault
Thu, 27 Oct 22
50/55

Comments: N/A

La orientación de las iglesias coloniales de Fuerteventura [CL]

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http://arxiv.org/abs/2209.15444


We use standard tools of Archaeoastronomy to approach the study of orientations, possibly astronomical, of a group of colonial Christian churches. We present preliminary results of the analysis of the precise spatial orientation of nearly fifty chapels and churches of the Canary Island of Fuerteventura (Spain), most of them built from the period of the Norman conquest in the fifteenth century to the nineteenth century. Although some small chapels belonging to the manorial power of the island and other modern churches do not have a well-defined pattern of orientations, the vast majority of the religious constructions of the island (about 35 of the 48 analyzed) have their axis oriented within the solar range, between the extreme azimuths of the annual movement of the Sun when crossing the local horizon. Unlike what was found in other islands of the archipelago, these results suggest that the religious architecture of Fuerteventura faithfully follows the prescriptions contained in the texts of early Christian writers.

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M. Muratore and A. Gangui
Mon, 3 Oct 22
13/55

Comments: Article in Spanish including 6 figures and 1 table

Samuil Kaplan and the development of astrophysical research at the Lviv University (dedicated to the 100th anniversary of his birth) [CEA]

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http://arxiv.org/abs/2209.09494


Samuil Kaplan (1921-1978) was a productive and famous astrophysicist. He was affiliated with a number of scientific centers in different cities of former Soviet Union. The earliest 13 years of his career, namely in the 1948-1961 years, he worked in Lviv University in Ukraine (then it was called the Ukrainian Soviet Socialist Republic). In the present paper, the Lviv period of his life and scientific activity is described on the basis of archival materials and his published studies. Kaplan arrived in Lviv in June 1948, at the same month when he obtained the degree of Candidate of science. He was a head of the astrophysics sector at the Astronomical Observatory of the University, was a professor of department for theoretical physics as well as the founder and head of a station for optical observations of artificial satellites of Earth. He was active in the organization of the astronomical observational site outside of the city. During the years in Lviv, Kaplan wrote more than 80 articles and 3 monographs in 9 areas. The focus of his interests at that time was on stability of circular orbits in the Schwarzschild field, on white dwarf theory, on space gas dynamics, and cosmic plasma physics, and turbulence, on acceleration of cosmic rays, on physics of interstellar medium, on physics and evolution of stars, on cosmology and gravitation, and on optical observations of Earth artificial satellites. Some of his results are fundamental for development of theory in these fields as well as of observational techniques. The complete bibliography of his works published during the Lviv period is presented. Respective scientific achievements of Samuil Kaplan are reviewed in the light of the current state of research in these areas.

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B. Novosyadlyj, B. Hnatyk, Y. Kulinich, et. al.
Wed, 21 Sep 22
21/68

Comments: 24 pages, 5 figures; accepted for publication in Europian Physical Journal H

Pieter Johannes van Rhijn, Kapteyn's Astronomical Laboratory and the Plan of Selected Areas [CL]

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http://arxiv.org/abs/2208.13496


In this contribution I discuss the Kapteyn Astronomical Laboratory during the period of Pieter Johannes van Rhijn’s directorate, which lasted from 1921 to 1957. It had developed under the founder Jacobus Cornelius Kapteyn into one of the leading astronomical research institutes in the world. When van Rhijn took over at the retirement of Kapteyn, it was in the process of coordinating Kapteyn’s Plan of Selected Areas. Van Rhijn’s research was solid and professional work, but in his papers he invariably stopped before discussing how his findings did fit into the larger scheme of things. He maybe was unimaginative but it did lack the link to the larger view towards the emerging picture of the structure of the Galaxy. Van Rhijn was unfortunate to be hampered throughout almost his complete directorate by factors, that severely limited his attempts to obtain more funding in spite of local support by his university. These were of course in the first place the Great Depression of the 1930s and the Second World War and its aftermath, while during most of the 1940s he suffered from tuberculosis. But also the remote location of Groningen compared to Leiden, where a major infrastructure led by three important protegees of Kapteyn was in place, and the governmental bias towards support for Leiden over Groningen was an important factor. Finally I examine the developments in the 1950s and the circumstances that made Adriaan Blaauw accept his appointment as van Rhijn’s successor in 1957 and initiate the beginnings of the revival under his leadership.

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P. Kruit
Tue, 30 Aug 22
6/76

Comments: Accepted by the Journal of Astronomical History and Heritage. For a version with high-res figures please see www.astro.rug.nl/~vdkruit/PJvRhijn.pdf

Reconstructing the lost eclipse events of the Saros spiral applying the Draconic gearing on the Antikythera Mechanism. The impact of the gearing errors on the pointers position [IMA]

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http://arxiv.org/abs/2208.10997


We present new observations concerning the procedure for the reconstruction of the lost eclipse events engraved in the Saros spiral cells of the Antikythera Mechanism. For the reconstructed eclipse events we applied the assumed, albeit missing, Draconic gearing of the Antikythera Mechanism, which was probably a part of the Mechanism gearing, representing the fourth lunar motion, the Draconic cycle. The Draconic gearing is very critical for the eclipse prediction and defines whether an eclipse will occur. For our research we created a program which presents the phase of the four lunar cycles and the position of the Draconic pointer relative to the ecliptic limits. After calibrating the software according to the preserved eclipse events, the lost eclipse events of the Saros spiral were calculated and discussed. The procedure for the calculation of the events times by using solely the Mechanism is also presented. The eccentricity error of a gear which is preserved on the ancient prototype is discussed. An experimental setup facilitated the analysis of the mechanical characteristics of gears with triangular teeth and the errors. The experimental study of the gears errors revealed the strong impact the Antikythera Mechanism pointers have on the results.

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A. Voulgaris, C. Mouratidis and A. Vossinakis
Wed, 24 Aug 22
45/67

Comments: Manuscript (26 pages and 13 figures) and Supplementary material (36 pages and 92 figures)

Interviews about modern astrometry [IMA]

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http://arxiv.org/abs/2208.09332


Michael Perryman has interviewed some of the scientists and project leaders in the Hipparcos and Gaia missions, the interviews with photos of the persons are given at his site: https://www.michaelperryman.co.uk . Michael has also written essays — 84 to date ! — about results from the Gaia mission and they are placed at his site. Three of the interviews are with me and transcriptions, co-authored with Michael, are provided below with the titles: #1. An interview about astronomy and astrometry up to 1980. #2. An interview about the revival of astrometry after 1980. #3. The billion-star astrometry after 1990. The third interview begins in 1990 when I had the first ideas for a Hipparcos successor. In 1992 I made a detailed design with direct imaging on CCD detectors in a satellite proposal called Roemer. In 1993 a supposedly better option was proposed with the acronym GAIA where the capital “I” stood for Interferometer. In 1998, however, interferometry was shown to be unsuited for the purpose and we returned to the original idea from 1992 for the further development. The name was later changed to Gaia — for the sake of continuity.

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E. Høg
Mon, 22 Aug 22
22/53

Comments: 62 pages (=1+22+19+20, including abstracts and references)

European historical evidence of the supernova of AD 1054 coins of Constantine IX and SN 1054 [CL]

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http://arxiv.org/abs/2206.00392


We investigate a possible depiction of the famous SN 1054 event in specially minted coins produced in the Eastern Roman Empire in 1054 A.D. On these coins, we investigate if the head of the Emperor, Constantine IX, might represent the Sun with a bright ‘star’ on either side – Venus in the east and SN 1054 in the west, perhaps also representing the newly split Christian churches. We explore the idea that the eastern star represents the stable and well-known Venus and the Eastern Orthodox Church, while the western star represents the short-lived ‘new star’ and the ‘fading’ Western Catholic church. We examined 36 coins of this rare Constantine IX Class IV batch. While no exact date could be associated to any of these coins, they most likely were minted during the last six months of Constantine IX’s rule in 1054. We hypothesise that the stance of the church concerning the order of the Universe, as well as the chaos surrounding the Great Schism, played a crucial role in stopping the official reporting of an obvious event in the sky, yet a dangerous omen. A temporal coincidence of all these events could be a reasonable explanation as well.

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M. Filipović, J. Payne, T. Jarret, et. al.
Thu, 2 Jun 22
55/57

Comments: Accepted in European Journal of Science and Theology

The Cavendish Computors: The women working in scientific computing for Radio Astronomy [IMA]

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http://arxiv.org/abs/2205.07267


A discussion of the history of scientific computing for Radio Astronomy in the Cavendish Laboratory of the University of Cambridge in the decades after the Second World War. This covers the development of the aperture synthesis technique for Radio Astronomy and how that required using the new computing technology developed by the University’s Mathematical Laboratory: the EDSAC, EDSAC 2 and TITAN computers. It looks at the scientific advances made by the Radio Astronomy group, particularly the assembling of evidence which contradicted the Steady State Hypothesis. It also examines the software advances that allowed bigger telescopes to be built: the Fast Fourier Transform (FFT) and the degridding algorithm. Throughout, the contribution of women is uncovered, from the diagrams they drew for scientific publications, through programming and operating computers, to writing scientific papers.

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V. Allan
Tue, 17 May 22
29/95

Comments: First presented at the Joint BSHM CSHPM/SCHPM Conference People, Places, Practices at St Andrews, July 2021

The orientation of Jesuit churches in the Chiquitos missions of eastern Bolivia [CL]

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http://arxiv.org/abs/2205.00469


The Jesuit missions in South America were an important and unique advance in Christian evangelisation on the continent until the expulsion of the Order in 1767. Although the history and cultural aspects of these missions and their most iconic buildings have been extensively studied, the archaeoastronomy of the Guaran\’i peoples of the Province of Paraquaria (Province of Paraguay) has only been recently considered, with the existing studies focusing primarily on the orientation of their churches. The paper presented here, which is the first archaeoastronomical study of the Jesuit missions of Chiquitos in eastern Bolivia, is an attempt to continue and complement the previous archaeoastronomical studies of the region. The methodologies employed involved the analysis of the Jesuit churches that currently exist in this region, namely, the on-site measurements of the orientations of eight churches currently standing and the ruins of a ninth church of which only a free-standing bell tower and parts of the side walls remain preserved. The orientation measurements of a tenth church, which we were unable to visit, were determined via the use of satellite maps. The landscape surrounding these churches was then examined in detail and furthermore, a detailed cultural and historical study of the characteristics of the villages where the churches are located was carried out. Our results show that, unlike the churches of the Province of Paraquaria where meridian orientations in the north-south direction stand out, half of the studied churches have shown potential canonical orientations that seem to be aligned to solar phenomena, with three exhibiting precise equinoctial orientation. We propose reasons for these orientations, including the possible relevance of illumination effects on significant internal elements within the churches – effects that were generally sought in Baroque church architecture.

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A. Gangui
Tue, 3 May 22
36/82

Comments: PDF document including 1 table and 7 figures

Magnetohydrodynamic Turbulence: Chandrasekhar's Contributions \& Beyond [CL]

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http://arxiv.org/abs/2204.12799


In the period of 1948-1955, Chandrasekhar wrote four papers on magnetohydrodynamic (MHD) turbulence, which are the first set of papers in the area. The field moved on following these pioneering efforts. In this paper, I will briefly describe important works of MHD turbulence, starting from those by Chandrasekhar.

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M. Verma
Thu, 28 Apr 22
8/70

Comments: To appear in J. Astrophys. Astr

Sometimes size does not matter [CL]

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http://arxiv.org/abs/2204.11780


Cosmological fine-tuning has traditionally been associated with the narrowness of the intervals in which the parameters of the physical models must be located to make life possible. A more thorough approach focuses on the probability of the interval, not on its size. Most attempts to measure the probability of the life-permitting interval for a given parameter rely on a Bayesian statistical approach for which the prior distribution of the parameter is uniform. However, the parameters in these models often take values in spaces of infinite size, so that a uniformity assumption is not possible. This is known as the normalization problem. This paper explains a framework to measure tuning that, among others, deals with normalization, assuming that the prior distribution belongs to a class of maximum entropy (maxent) distributions. By analyzing an upper bound of the tuning probability for this class of distributions the method solves the so-called weak anthropic principle, and offer a solution, at least in this context, to the well-known lack of invariance of maxent distributions. The implication of this approach is that, since all mathematical models need parameters, tuning is not only a question of natural science, but also a problem of mathematical modeling. Cosmological tuning is thus a particular instantiation of a more general scenario. Therefore, whenever a mathematical model is used to describe nature, not only in physics but in all of science, tuning is present. And the question of whether the tuning is fine or coarse for a given parameter — if the interval in which the parameter is located has low or high probability, respectively — depends crucially not only on the interval but also on the assumed class of prior distributions. Novel upper bounds for tuning probabilities are presented.

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D. Díaz-Pachón, O. Hössjer and R. II
Tue, 26 Apr 22
38/74

Comments: 31 pages, 1 table

Renumbering of the Antikythera Mechanism Saros cells, resulting from the Saros spiral mechanical apokatastasis [IMA]

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http://arxiv.org/abs/2204.11136


After studying the design geometry of the Antikythera Mechanism Saros spiral, new critical geometrical/mechanical characteristics of the Back plate design were detected. The geometrical characteristics related to the symmetry of the Antikythera Mechanism design, are independent to the present irregular deformation of the Mechanism parts and were used as calibration points for the Saros spiral cells positional measurements. The Saros cells numbering was recalculated using the calibration points position. A correction of minus one to the currently accepted numbering of the Saros cells was applied. Following the new numbering, a new proper position for the (displaced) Saros pointer axis-g, in graphic design environment was calculated. The measurements were tested on a bronze reconstruction of the Back plate, by the authors. This research leads to a new important result that the Saros does not start in a random or arbitrary date but only when a solar eclipse occurs within a month. Additional results were also calculated regarding the symmetry of the eclipse events/sequence. The new Saros cell numbering strongly affects the calculations for the initial starting date of the Saros spiral and the eclipse events scheme of the Antikythera Mechanism.

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A. Voulgaris, C. Mouratidis, A. Vossinakis, et. al.
Tue, 26 Apr 22
49/74

Comments: 22 pages, 13 figures

Biocosmology: Biology from a cosmological perspective [CL]

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http://arxiv.org/abs/2204.09379


The Universe contains everything that exists, including life. And all that exists, including life, obeys universal physical laws. Do those laws then give adequate foundations for a complete explanation of biological phenomena? We discuss whether and how cosmology and physics must be modified to be able to address certain questions which arise at their intersection with biology. We show that a universe that contains life, in the form it has on Earth, is in a certain sense radically non-ergodic, in that the vast majority of possible organisms will never be realized. We argue from this that complete explanations in cosmology require a mixture of reductionist and functional explanations.

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M. Cortês, S. Kauffman, A. Liddle, et. al.
Thu, 21 Apr 22
29/73

Comments: 28 pages

The pioneering scientific endeavor of the first Colombian modern astronomer José María González Benito (1843-1903) [CL]

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http://arxiv.org/abs/2204.08097


Astronomical interest within the current Colombian territory has its roots in the Botanical Expedition of the New Kingdom of Granada, which stimulated the creation of an astronomical observatory in 1803, the first one established in the New World to pursue systematic observations and meteorological studies. After the death in 1816 of its first director, Francisco Jos\’e de Caldas, during the convulsive independence period, no major astronomical observations were made for decades, with few exceptions. In this work we delve into the contributions of the astronomer Jos\’e Mar\’ia Gonz\’alez Benito, the main reactivator of the National Astronomical Observatory of Colombia in the second half of the 19th century, pointing out his pioneering efforts that put worldwide attention to it, and to his own private observatory making him one of the most committed figures to the development of astronomical sciences in the country and the most renowned Colombian in the international astronomical research scene of his time.

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F. Cárdenas, S. Domínguez and J. Cuellar
Tue, 19 Apr 22
50/52

Comments: 41 pages, 16 figures, 4 tables. Submitted to the Journal for the History of Astronomy

Do anthropic arguments really work? [CEA]

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http://arxiv.org/abs/2204.07509


The anthropic explanation for the peculiarly small observed value of the cosmological constant $\Lambda_{\rm obs}$ argues that this value promotes the formation of stars, planets, and ultimately of observers such as ourselves. I show that a recent analytic model of cosmic star formation predicts that although $\Lambda_{\rm obs}$ maximises the overall efficiency of star formation in the universe, the probability of generating observers peaks at $\sim400-500 \, \Lambda_{\rm obs}$. These preliminary results suggest that an immediate connection between star formation efficiency and observers’ generation is not straightforward, and highlight the subtleties involved with the application of anthropic reasoning.

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D. Sorini
Mon, 18 Apr 22
15/34

Comments: contribution to the 2022 Cosmology session of the 56th Rencontres de Moriond

A Solution to Galileo's Enigma "Mostro Son Io" [CL]

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http://arxiv.org/abs/2204.07525


Galileo Galilei was a skilled writer and explored several genres, from the well-known scientific writings (often in the form of dialogs) to theater and poetry. His last published poem, “Mostro son io” (A Monster am I), is a riddle written in the form of a sonnet. We suggest that the solution to Galileo’s riddle is the Zodiac.

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G. Busetto and A. Angelis
Mon, 18 Apr 22
34/34

Comments: N/A

The Initial Calibration Date of the Antikythera Mechanism after the Saros spiral mechanical Apokatastasis [CL]

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http://arxiv.org/abs/2203.15045


This work analyzes the phase correlation of the three lunar cycles and the Saros/Exeligmos cycle, after the study of the chapter About Exeligmos in Introduction to the Phenomena by Geminus. Geminus, refers that each Exeligmos cycle began on very specific and rare dates, when the Moon positioned at the points of the three lunar cycles beginning: New moon at Apogee and at the Node. The extremely large duration of the Annular Solar eclipse occurred on December 22 178BC (Saros series 58), marks the start of the Prominent Saros Cycle Apokatastasis. The next day, 23 December 178BC, the Winter Solstice started. During these two neighboring dates, the celebration of the religious festival of Isia started in Egypt and the Hellenistic Greece. After the analysis of the Mechanism’s Parapegma events specific position, 22/23 December 178BC is an ideal, functional and representative initial date, in order to calibrate the initial position of the Mechanism’s pointers.

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A. Voulgaris, C. Mouratidis and A. Vossinakis
Wed, 30 Mar 22
76/77

Comments: 29 pages, 8 figures

Why the mean anomaly at epoch is not used in tests of non-Newtonian gravity? [CL]

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http://arxiv.org/abs/2203.12951


The mean anomaly at epoch $\eta$ is one of the standard six Keplerian orbital elements in terms of which the motion of the two-body problem is parameterized. Along with the argument of pericenter $\omega$, $\eta$ experiences long-term rates of change induced, among other things, by general relativity and several modified models of gravity. Thus, in principle, it may be fruitfully adopted together with $\omega$ in several tests of post-Newtonian gravity performed with astronomical and astrophysical binary systems. This would allow to enhance the gravitational signature one is interested in and to disentangle some competing disturbing effects acting as sources of systematic bias. Nonetheless, for some reasons unknown to the present author, $\eta$ has never been used so far by astronomers in actual data reductions. This note aims to raise interest in the community about the possible practical use of such an orbital element or, at least, to induce experts in astronomical data processing to explicitly make clear if it is not possible to use $\eta$ for testing gravitational models and, in this case, why.

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L. Iorio
Fri, 25 Mar 22
20/46

Comments: LaTex2e, 7 pages, no figures, no tables

Solar rotation elements $i, Ω$ and period determined using sunspot observations by Ruđer Bošković in 1777 [SSA]

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http://arxiv.org/abs/2203.11745


Ru{\dj}er Bo\v{s}kovi\’c developed methods for determination of solar rotation elements: the solar equator inclination i, the longitude of the node {\Omega} and the period of solar rotation. In his last work Opera pertinentia ad opticam et astronomiam, published in 1785, in the chapter Opuscule II he described his methods, the formulae with figure descriptions and an example for calculation of the solar rotation elements with detailed numerical explanation using his own observations performed in September 1777. The original numerical procedure was performed using logarithmic formulae. In present work we give a description of the original results of R. Bo\v{s}kovi\’c and compare them with our recalculated values.

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M. Husak, R. Brajša and D. ŠPoljarić
Wed, 23 Mar 22
38/76

Comments: 7 pages, 2 figures, published Contributed paper (oral presentation) at the International Advent Workshop 17th – 18th December 2020, Zagreb – Graz, Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia and IGAM, Institute of Physics, Karl-Franzens University Graz, Austria

History of Solar Neutrino Observations [CL]

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http://arxiv.org/abs/2202.12421


The first solar neutrino experiment led by Raymond Davis Jr. showed a deficit of neutrinos relative to the solar model prediction, referred to as the “solar neutrino problem” since the 1970s. The Kamiokande experiment led by Masatoshi Koshiba successfully observed solar neutrinos, as first reported in 1989. The observed flux of solar neutrinos was almost half the prediction and confirmed the solar neutrino problem. This problem was not resolved for some time due to possible uncertainties in the solar model. In 2001, it was discovered that the solar neutrino problem is due to neutrino oscillations by comparing the Super-Kamiokande and Sudbury Neutrino Observatory results, which was the first model-independent comparison. Detailed studies of solar neutrino oscillations have since been performed, and the results of solar neutrino experiments are consistent with solar model predictions when the effect of neutrino oscillations are taken into account. In this article, the history of solar neutrino observations is reviewed with the contributions of Kamiokande and Super-Kamiokande detailed.

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M. Nakahata
Mon, 28 Feb 22
34/38

Comments: 29 pages, 20 figures, accepted by PTEP as a paper for “A special issue in memory of Masatoshi Koshiba, a pioneer in experimental particle physics and astrophysics”

Integrating Dark Matter, Modified Gravity, and the Humanities [CL]

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http://arxiv.org/abs/2202.11469


Editorial of a special issue on dark matter & modified gravity, distributed across the journals Studies in History and Philosophy of Modern Physics and Studies in History and Philosophy of Science. Published version of the open access editorial (in SHPS) available here: https://doi.org/10.1016/j.shpsa.2021.08.015. The six papers are collected here: https://www.sciencedirect.com/journal/studies-in-history-and-philosophy-of-science-part-b-studies-in-history-and-philosophy-of-modern-physics/special-issue/10CR71RJLWM.

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N. Martens, M. Sahuquillo, E. Scholz, et. al.
Thu, 24 Feb 22
35/52

Comments: 14 pages, 0 figures, editorial of a special issue on dark matter & modified gravity

The Genesis of the No-Boundary Wave Function of the Universe [CL]

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http://arxiv.org/abs/2202.07020


Brief recollections by the author about how he and Stephen Hawking arrived at the theory of the No-Boundary Quantum State of the Universe

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J. Hartle
Wed, 16 Feb 22
50/69

Comments: 14 pages, 5 figures

Dark Matter Realism [CL]

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http://arxiv.org/abs/2202.00958


According to the standard model of cosmology, LambdaCDM, the mass-energy budget of the current stage of the universe is not dominated by the luminous matter that we are familiar with, but instead by some form of dark matter (and dark energy). It is thus tempting to adopt scientific realism about dark matter. However, there are barely any constraints on the myriad of possible properties of this entity — it is not even certain that it is a form of matter. In light of this underdetermination I advocate caution: we should not (yet) be dark matter realists. The “not(-yet)-realism” that I have in mind is different from Hacking’s (1989) anti-realism, in that it is semantic rather than epistemological. It also differs from the semantic anti-realism of logical empiricism, in that it is naturalistic, such that it may only be temporary and does not automatically apply to all other unobservables (or even just to all other astronomical unobservables, as with Hacking’s anti-realism). The argument is illustrated with the analogy of the much longer history of the concept of a gene, as the current state of the concept of dark matter resembles in some relevant ways that of the early concept of genes.

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N. Martens
Thu, 3 Feb 22
24/56

Comments: 22 pages, 2 figures, Winner of the New Directions in Philosophy of Cosmology Essay Award (Dec 2020)

Unprecedented Daylight Display of Kreutz Sungrazers in AD 363? [EPA]

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http://arxiv.org/abs/2202.01164


In the context of the recently proposed contact-binary model (Sekanina 2021), I investigate the circumstances of the first perihelion passage of the Kreutz sungrazers in orbits with barycentric periods near 735 yr, following the initial near-aphelion splitting of the presumed progenitor, Aristotle’s comet of 372 BC. Given favorable conditions at this breakup and at episodes of secondary fragmentation in its aftermath, the fragments should have arrived at their first perihelion nearly simultaneously, reminiscent of the anticipated outcome for the two-superfragment model’s perihelion return of AD 356 (Sekanina & Chodas 2004). The relevant case of a swarm of Kreutz sungrazers is examined to appraise possible scientific ramifications of the brief remark by Ammianus Marcellinus, a Roman historian, that “in broad daylight comets were seen” in late AD 363, only seven years later. The tested scenario, which does not contradict Ammianus’ narrative and is consistent with the contact-binary model, involves a set of ten sungrazers visible in the daytime, all reaching perihelion over a period of 4.6 days. As part of this work, I comment on the role of the rapidly developing, brilliant post-perihelion tail; revise the apparent magnitude typical for the first and last naked-eye sightings; compare the visibility conditions in full daylight, in twilight, and at night; and, for the first time, present circumstantial evidence that favors comet X/1106 C1 as the parent to C/1843 D1 rather than to C/1882 R1 and C/1965 S1.

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Z. Sekanina
Thu, 3 Feb 22
53/56

Comments: 33 pages, 10 figures, 14 tables

In Memoriam Cornelis de Jager [CL]

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http://arxiv.org/abs/2201.11496


Cornelis (“Kees”) de Jager, co-founder of “Solar Physics”, passed away in 2021. He was an exemplary human being, a great scientist, and had large impact on our field. In this tribute we first briefly summarize his life and career and then describe some of his solar activities, from his PhD thesis on the hydrogen lines in 1952 to the book on cycle-climate relations completed in 2020.

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R. Rutten, O. Engvold and A. Nieuwenhuizen
Fri, 28 Jan 22
35/64

Comments: Compliant with publisher stipulations the ArXiv version is the initial manuscript submitted in July 2021. It does not reflect changes made by the journal editor and publisher. Its posting waited on the required publication DOI

Historical Chinese efforts to determine longitude at sea [CL]

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http://arxiv.org/abs/2201.08467


High-level Chinese cartographic developments predate European innovations by several centuries. Whereas European cartographic progress — and in particular the search for a practical solution to the perennial “longitude problem” at sea — was driven by persistent economic motivations, Chinese mapmaking efforts responded predominantly to administrative, cadastral and topographic needs. Nevertheless, contemporary Chinese scholars and navigators, to some extent aided by experienced Arab navigators and astronomers, developed independent means of longitude determination both on land and at sea, using a combination of astronomical observations and timekeeping devices that continued to operate adequately on pitching and rolling ships. Despite confusing and speculative accounts in the current literature and sometimes overt nationalistic rhetoric, Chinese technical capabilities applied to longitude determination at sea, while different in design from European advances owing to cultural and societal circumstances, were at least on a par with those of their European counterparts.

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R. Grijs
Mon, 24 Jan 22
54/59

Comments: 23 pages incl. 9 figures; Journal of Astronomical History and Heritage, in press (March 2022 issue)

On Circular Orbits in Einstein's Theory of Gravitation [CL]

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http://arxiv.org/abs/2201.07971


The preprint is an English translation of the paper by famous astrophysicist Samuil Kaplan (1921-1978) “O krugovykh orbitakh v teorii tyagoteniya Einsteina (On circular orbits in Einstein’s theory of gravitation)”, published in 1949 in the Journal of Experimental and Theoretical Physics (Vol. 19, No. 10, pp. 951-952) in Russian. This important 1 and 1/3 page paper is still inaccessible to a wide range of experts and students due to the lack of such translation. This paper is the first scientific publication of Samuil Kaplan and the pioneering work in this field. The aim of this presentation is to make the article available to a wide range of experts in the field of general relativity, relativistic astrophysics and the history of science, as well as to honor its author on the occasion of the 100th anniversary of his birth.

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S. Kaplan
Fri, 21 Jan 22
30/60

Comments: 2 pages (The authors of the idea and translation are Bohdan Novosyadlyj and Roman Plyatsko.)

The Nobel prizes in physics for astrophysics and gravitation and the Nobel prize for black holes: Past, present, and future [CL]

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http://arxiv.org/abs/2112.14346


We analyze the Nobel prizes in physics for astrophysics and gravitation since the establishment of the prize and highlight the 2020 Nobel prize for black holes. In addition, we comment on the names that could have received the prize in astrophysics and gravitation, and draw attention to the individuals who made outstanding contributions to black hole physics and astrophysics and should be mentioned as possible and deserved recipients of the prize. We speculate about the branches of research in astrophysics and gravitation, with an emphasis on the latter, that can be contemplated in the future with a Nobel prize.

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J. Lemos
Fri, 7 Jan 22
23/34

Comments: 26 pages, 7 figures

The Great Aurora of 4 February 1872 observed by Angelo Secchi in Rome [CL]

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http://arxiv.org/abs/2201.01171


Observation of auroras at low latitudes is an extremely rare event typically associated with major magnetic storms due to intense Earth-directed Coronal Mass Ejections. Since these energetic events represent one of the most important components of space weather their study is of paramount importance to understand the Sun-Earth connection. Due to the rarity of these events, being able to access all available information for the few cases studied is equally important. Especially if we refer to historical periods in which current accurate observations from ground-based instruments or from space were not available. Certainly, among these events we must include the great aurora of February 4, 1872. An event whose effects have been observed in different regions of the Earth. What we could consider today a global event, especially for its effects on the communication systems of the time, such as the transatlantic cable that allowed a connection between the United States and Europe since 1866. In this paper we describe the main results of the observations and studies carried out by Angelo Secchi at the Observatory of the Roman College and described in his “Memoria sull’Aurora Elettrica del 4 Febbraio 1872” for the Notes of the Pontifical Academy of new Lincei. This note is extremely modern both in its multi-instrumental approach to the study of these phenomena and in its association between solar-terrestrial connection and technological infrastructures on the Earth. The Secchi’s note definitely represents the first example of analysis and study of an event on a global scale, such as the Atlantic cable, affecting the Earth. What we nowadays call an extreme space weather event.

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F. Berrilli and L. Giovannelli
Wed, 5 Jan 22
7/54

Comments: 10 pages, 5 figures

The history of the observatory library at Østervold in Copenhagen, Denmark [IMA]

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http://arxiv.org/abs/2201.01054


About fifty years after the work that astronomer Tycho Brahe carried out while living on the island of Hven had made him world famous, King Christian IV of Denmark built the Trinity Buildings in Copenhagen. The Tower observatory was opened in 1642, and it housed the astronomers from the University of Copenhagen until 1861 when a new, modern observatory was built at {\O}stervold in the eastern part of the city. In 1996, all the University astronomers from the observatories at {\O}stervold and the small town of Brorfelde were relocated to the Rockefeller Buildings at {\O}sterbro, and the two observatories were closed. In this paper we focus on the library at the observatory in {\O}stervold, and its subsequent fate following the close-down of that observatory.

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S. Dorch and J. Petersen
Wed, 5 Jan 22
26/54

Comments: 13 pages, 17 figures

The curious case of Betelgeuse [SSA]

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http://arxiv.org/abs/2112.06076


Betelgeuse is the nearest red supergiant, one of the brightest stars in our sky, and statistically speaking it would be expected to be “typical”. Yet it exhibits many features that seem “curious”, to say the least. For instance it has a high proper motion. It rotates fast. It has little dust. It dimmed unexpectedly. Is any of these, and other, phenomena atypical, and taken together does it make Betelgeuse atypical? This is important to know, because we need to know whether Betelgeuse might be a prototype of red supergiants in general, or certain subclasses of red supergiants, since we can study it in such great detail. It is also important to know as it may be a link to understanding other, apparently atypical cases such as supernova 1987A, and maybe even such exotica as Thorne-.Zytkov objects. Studying this question in itself helps us understand how we deal with rarity and coincidence in understanding the Universe we live in.

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J. Loon
Tue, 14 Dec 21
89/98

Comments: Invited talk at the 16th Marcel Grossmann meeting

Introducing ASTROMOVES [IMA]

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http://arxiv.org/abs/2112.03090


The ASTROMOVES project studies the career moves and the career decision-making of astrophysicists. The astrophysicists participating have to have made at least two career moves after receiving their doctorates, which is usually between 4 and 8 years post PhD. ASTROMOVES is funded via the European Union and thus each participant must have worked or lived in Europe. Gender, ethnicity, nationality, marital status, and if they have children are some of the many factors for analysis. Other studies of the careers of astronomers and astrophysicists have taken survey approaches (Fohlmeister & Helling, 2012, 2014; Ivie et al., 2013; Ivie & White, 2015) laying a foundation upon which ASTROMOVES builds. For ASTROMOVES qualitative interviews are combined with publicly available information for the project, rather than surveys. Valuable information about career options and the decisions about where not to apply will be gathered for the first time. Those few studies that have used qualitative interviews often include both physicists and astrophysicists, nonetheless they have revealed issues that are important to ASTROMOVES such as the role of activism and the nuances of having children related to the long work hours culture (Ong, 2001; Rolin & Vainio, 2011). The global COVID-19 pandemic has slowed down the project; however, at the time of this writing 20 interviews have been completed. These interviews support previous research findings on how having a family plays an important role in career decision making, as well as the importance of mobility in building a career in astrophysics. Cultural Astronomy spans all aspects of the relationship between humans and the sky as well as all times ancient to the present; and thus, studying astronomers & astrophysicists who have a professional relationship to the sky is part of cultural astronomy, too.

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J. Holbrook
Tue, 7 Dec 21
84/91

Comments: 6 pages, 3 figures, 3 tables, SEAC conference 2021

From the Dining Room to the Coll{è}ge royal: The Scholarly Spaces of the Female Collaborators in Astronomy of J{é}r{ô}me Lalande [CL]

Posted on by

http://arxiv.org/abs/2111.07800


J{\’e}r{\^o}me Lalande, a famous French astronomer in the 18th century, collaborated throughout his career with several female calculators in astronomy: Nicole Reine Lepaute, Marie Louise Dupi{\’e}ry and Marie Jeanne Lefran{\c c}ois. Taking on highly technical tasks of calculation and sometimes observation, they also took on the scientific ”intendance” for the astronomer. This management of a part of the scholarly enterprise was mainly carried out from home, as were the astronomical calculations. This space was therefore both a family living space and a space for the production of knowledge. This article will focus on its material organization as well as on the dynamics that took place between the different places of knowledge involved here.

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I. Lémonon-Waxin
Tue, 16 Nov 21
3/97

Comments: in French

Reluctant Pioneer of Nuclear Astrophysics: Eddington and the Problem of Stellar Energy [CL]

Posted on by

http://arxiv.org/abs/2111.02096


During the years from 1917 to 1921, A.S. Eddington was intensely occupied with Einstein’s general theory of relativity and the epic eclipse expedition which confirmed one of the theory’s predictions. During the same period, he investigated the old problem of why the stars shine, which led him to suggest two different subatomic mechanisms as the source of stellar energy. One of them was the annihilation of matter and the other the building-up of helium from hydrogen. This paper is concerned with Eddington’s work in this area, a line of work to which he returned on and off during the 1920s but then abandoned. His decision to stop working on the stellar energy problem coincided with the first attempts to understand the problem in terms of nuclear physics and quantum mechanics. Why did Eddington not follow up his earlier work and why did he ignore the contributions of the nuclear physicists which in the late 1930s resulted in the first successful theories of stellar energy production?

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H. Kragh
Thu, 4 Nov 21
23/73

Comments: 13 pages, 2019 Paris conference on Eddington

The Fine-Tuning of the Universe for Life [CL]

Posted on by

http://arxiv.org/abs/2110.07783


When a physicist says that a theory is fine-tuned, they mean that it must make a suspiciously precise assumption in order to explain a certain observation. This is evidence that the theory is deficient or incomplete. One particular case of fine-tuning is particularly striking. The data in question are not the precise measurements of cosmology or particle physics, but a more general feature of our universe: it supports the existence of life. This chapter reviews this Fine-Tuning of the Universe for Life.

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L. Barnes
Mon, 18 Oct 21
4/68

Comments: 15 pages, 1 figure. Invited contribution to the Routledge Companion to Philosophy of Physics, edited By Eleanor Knox, Alastair Wilson

The physicist Enrique Loedel Palumbo in the Montevideo-Buenos Aires-La Plata scientific corridor: 1920-1930 [CL]

Posted on by

http://arxiv.org/abs/2110.03799


In this paper we consider Montevideo’s liberal progressive atmosphere towards the end of the nineteenth century and, within it, the trajectory of young science student Enrique Loedel Palumbo. We discuss some of his activities in Argentina, where he moved to study Physics at a new and well-equipped Physics Institute at the National University of La Plata, where he would later become a leading figure. Initially Loedel Palumbo worked on the structure of complex molecules based on their magnetic, electric and optical properties. Later, when Einstein visited Argentina in 1925, he had chance to exchange ideas, which led to the publication of the first of a series of papers on the Theory of Relativity in some of Germany’s leading scientific journals. Loedel Palumbo integrated fully with the intellectual life of his adopted country, becoming one of Argentina’s top physicists and philosophers of science of his day. He is a valuable example of the deep intertwining of the intellectual life of Uruguay and Argentina in the first-half of the twentieth century. Like his Argentine colleagues, he also experienced the consequences of living through a complex historical period.

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A. Gangui and E. Ortiz
Mon, 11 Oct 21
4/58

Comments: Article in Spanish, PDF document. Other related documents available at this http URL arXiv admin note: substantial text overlap with arXiv:1909.02558

The Life and Science of Thanu Padmanabhan [CL]

Posted on by

http://arxiv.org/abs/2110.03208


Thanu Padmanabhan was a renowned Indian theoretical physicist known for his research in general relativity, cosmology, and quantum gravity. In an extraordinary career spanning forty-two years, he published more than three hundred research articles, wrote ten highly successful technical and popular books, and mentored nearly thirty graduate students and post-doctoral fellows. He is best known for his deep work investigating gravitation as an emergent thermodynamic phenomenon. He was an outstanding teacher, and an indefatigable populariser of science, who travelled very widely to motivate and inspire young students. Paddy, as he was affectionately known, was also a close friend to his students and collaborators, treating them as part of his extended academic family. On September 17, 2021 Paddy passed away very unexpectedly, at the age of sixty-four and at the height of his research career, while serving as a Distinguished Professor at the Inter-University Centre for Astronomy and Astrophysics, Pune. His untimely demise has come as a shock to his family and friends and colleagues. In this article, several of them have come together to pay their tributes and share their fond memories of Paddy.

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J. Bagla, K. Bhattacharya, S. Chakraborty, et. al.
Fri, 8 Oct 21
58/70

Comments: In Memoriam of Prof. T. Padmanabhan (1957-2021)

Life, the universe and the hidden meaning of everything [CL]

Posted on by

http://arxiv.org/abs/2109.10241


It is hard to look at the universe and not wonder about the meaning, of, well, everything. A natural question is whether what we see is a sign of intelligent design. The antithesis of design would be a random universe or, assuming laws of physics, one whose fundamental physical parameters were randomly selected, but conditioned on life (ourselves) being here to observe it. In unpublished work, the British physicist Dennis Sciama argued that such a randomly selected universe would display a statistical signature. He concluded that a random universe would almost certainly have parameters only just allowing for the possibility of life. Here we consider whether this signature is definitive. We find that with plausible additional assumptions Sciama’s signature would appear to reverse: Were our universe random, it could give the false impression of being intelligently designed, with the fundamental constants appearing to be fine-tuned to a strong probability for life to emerge and be maintained.

Read this paper on arXiv…

Z. Wang and S. Braunstein
Wed, 22 Sep 21
57/57

Comments: 6 pages, 2 figures. Request for comments

Probable identification of the impact craters associated with two luminous historical lunar flashes [EPA]

Posted on by

http://arxiv.org/abs/2108.08148


We have reviewed and analyzed the lunar luminous events observations by William Herschel during the peak of the Lyrid meteor shower of 1787 and Leon Stuart near the peak of the Leonid meteor shower of 1953, seeking the impact craters that these events presumably formed. Evidence is presented that identifies two cold spot fresh craters as the expected candidates.

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W. Bruckman and A. Ruiz
Thu, 19 Aug 21
3/54

Comments: arXiv admin note: text overlap with arXiv:1804.08716

The Dark Side of the Universe [CL]

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http://arxiv.org/abs/2108.01691


A view on the history and current status of dark matter and dark energy, at a fairly introductory level.

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A. Rújula
Thu, 5 Aug 21
9/57

Comments: 26 pages. 11 figures

Archaeoastronomical study of Christian churches in Fuerteventura [CL]

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http://arxiv.org/abs/2106.13800


We present an archaeoastronomical study of the orientations of the colonial Christian churches on the island of Fuerteventura, in the Canary Islands, Spain, mostly built from the period of the Norman conquest in the 15th century to the 19th century. Our goal is to analyze the possible astronomical influence on the orientation of these churches. Preliminary results suggest that the vast majority of the island’s religious constructions have their axes oriented within the solar range, between the extreme azimuths of the annual movement of the Sun as it crosses the local horizon. This differs from what was found on the islands of Lanzarote and La Gomera (also in the Canaries) previously studied.

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M. Muratore and A. Gangui
Mon, 28 Jun 21
22/51

Comments: Published version available at this http URL

Are We Entering a Paradigm Shift for Dark Matter? [CL]

Posted on by

http://arxiv.org/abs/2106.10327


While the LCDM framework has been incredibly successful for modern cosmology, it requires the admission of two mysterious substances as a part of the paradigm, dark energy and dark matter. Although this framework adequately explains most of the large-scale properties of the Universe (i.e., existence and structure of the CMB, the large-scale structure of galaxies, the abundances of light elements and the accelerating expansion), it has failed to make significant predictions on smaller scale features such as the kinematics of galaxies and their formation. In particular, the rotation curves of disk galaxies (the original observational discovery of dark matter) are better represented by non-Newtonian models of gravity that challenge our understanding of motion in the low acceleration realm (much as general relativity provided an extension of gravity into the high acceleration realm e.g., blackholes). The tension between current cold dark matter scenarios and proposed new formulations of gravity in the low energy regime suggests an upcoming paradigm shift in cosmology. And, if history is a guide, observations will lead the way.

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J. Schombert
Thu, 24 Jun 21
42/54

Comments: 15 pages, no figures, talk, rejected by numerous philosophy journals

El limite de Chandrasekhar para principiantes / Chandrasekhar limit for beginners [CL]

Posted on by

http://arxiv.org/abs/2106.08933


In a brief article published in 1931 and expanded in 1935, the Indian astrophysicist Subrahmanyan Chandrasekhar shared an important astronomical discovery where he introduced what is now known as Chandrasekhar limit. This limit establishes the maximum mass that a white dwarf can reach, which is the stellar remnant that is generated when a low mass star has used up its nuclear fuel. The present work has a double purpose. The first is to present a heuristic derivation of the Chandrasekhar limit. The second is to clarify the genesis of the discovery of Chandrasekhar, as well as the conceptual aspects of the subject. The exhibition only uses high school algebra, as well as some general notions of classical physics and quantum theory.

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J. Pinochet
Thu, 17 Jun 21
36/74

Comments: 14 pages, 2 figures, Text in Spanish

The Noonday Argument: Fine-Graining, Indexicals, and the Nature of Copernican Reasoning [CL]

Posted on by

http://arxiv.org/abs/2106.07738


Typicality arguments attempt to use the Copernican Principle to draw conclusions about the cosmos and presently unknown conscious beings within it. The most notorious is the Doomsday Argument, which purports to constrain humanity’s future from its current lifespan alone. These arguments rest on a likelihood calculation that penalizes models in proportion to the number of distinguishable observers. I argue that such reasoning leads to solipsism, the belief that one is the only being in the world, and is therefore unacceptable. Using variants of the “Sleeping Beauty” thought experiment as a guide, I present a framework for evaluating observations in a large cosmos: Fine Graining with Auxiliary Indexicals (FGAI). FGAI requires the construction of specific models of physical outcomes and observations. Valid typicality arguments then emerge from the combinatorial properties of third-person physical microhypotheses. Indexical (observer-relative) facts do not directly constrain physical theories. Instead they serve to weight different provisional evaluations of credence. These weights define a probabilistic reference class of locations. As indexical knowledge changes, the weights shift. I show that the self-applied Doomsday Argument fails in FGAI, even though it can work for an external observer. I also discuss how FGAI could handle observations in large universes with Boltzmann brains.

Read this paper on arXiv…

B. Lacki
Wed, 16 Jun 21
45/57

Comments: 34 pages, 12 figures, 2 tables of examples, submitted

Cosmic Meteorology [CL]

Posted on by

http://arxiv.org/abs/2105.12559


Mike Lockwood and Mathew Owens discuss how eclipse observations are aiding the development of a climatology of near-Earth space

Read this paper on arXiv…

M. Lockwood and M. Owens
Thu, 27 May 21
62/62

Comments: Author-produced copy of published version in Astronomy and Geophysics

Expecting the unexpected in the search for extraterrestrial life [IMA]

Posted on by

http://arxiv.org/abs/2105.09055


On page 10 of the 2018 National Academies Exoplanet Science Strategy document (NASEM 2018), ‘Expect the unexpected’ is described as a general principle of the exoplanet field. But for the next 150 pages, this principle is apparently forgotten, as strategy decisions are repeatedly put forward based on our expectations. This paper explores what exactly it might mean to ‘expect the unexpected’, and how this could possibly be achieved by the space science community. An analogy with financial investment strategies is considered, where a balanced portfolio of low/medium/high-risk investments is recommended. Whilst this kind of strategy would certainly be advisable in many scientific contexts (past and present), in certain contexts, especially exploratory science, a significant disanalogy needs to be factored in: financial investors cannot choose low-risk high-reward investments, but sometimes scientists can. The existence of low-risk high-impact projects in cutting-edge space science significantly reduces the warrant for investing in high-risk projects, at least in the short term. However, high-risk proposals need to be fairly judged alongside medium- and low-risk proposals, factoring in both the degree of possible reward and the expected cost of the project. Attitudes towards high-risk high-impact projects within NASA since 2009 are critically analysed.

Read this paper on arXiv…

P. Vickers
Thu, 20 May 21
5/56

Comments: N/A

A translation of L. Euler's "On the motion of comets in parabolic orbits, having the Sun in the focus" [CL]

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http://arxiv.org/abs/2105.03340


This is a translation from Latin of E840 ‘De motu cometarum in orbitis parabolicis, solem in foco habentibus’, in which Euler addresses six problems related to comets in heliocentric parabolic orbits. Problem 1: Find the true anomaly of a heliocentric comet from the latus rectum of the orbit and the medium Earth to Sun distance. Problem 2: Find the orbit of a heliocentric comet from three given positions. Problem 3: Knowing the orbit of a comet, and the instant in time in which it dwells in the perihelion, define its longitude and latitude at any time. Problem 4: From two locations of a heliocentric comet, find the inclination of the comet’s orbit in relation to the ecliptic, and the positions of the nodes. Problem 5: From the time before or after the comet had reached the perihelion, and from the comet’s distance to the perihelion as seen from the Sun, find the same distance in another time before or after it had appeared in the perihelion. Problem 6: Find the orbit of a comet from three given heliocentric longitudes and latitudes. From these problems, several corollaries and scholia are derived.

Read this paper on arXiv…

S. Bistafa
Mon, 10 May 21
5/60

Comments: 20 pages, 8 figures

A translation of L. Euler's "Simple determination of the orbit of a comet, when it is possible to observe its passage across the ecliptic twice" [CL]

Posted on by

http://arxiv.org/abs/2105.03321


This is the translation from Latin of E547 ‘Determinatio facilis orbitae cometae, cuius transitum per eclipticam bis observare licuit’, in which Euler addresses the determination of a comet’s parabolic orbit, with the Sun at the focus, from two astronomical observations from the earth, when the comet crosses the ecliptic at the ascending and descending nodes. The key point of the calculation is the solution of a fourth degree polynomial, from which the determination of the orbital parameters are determined from one of its roots.

Read this paper on arXiv…

S. Bistafa
Mon, 10 May 21
21/60

Comments: 10 pages, 6 figures

European Historical Evidence of the Supernova of AD 1054 Balkan Medieval Tombstones [IMA]

Posted on by

http://arxiv.org/abs/2105.02119


In a previous work, we establish that the acclaimed ‘Arabic’ records of SN 1054 from ibn Butlan originate from Europe. Also, we reconstructed the European sky at the time of the event and find that the ‘new star’ (SN 1054) was in the west while the planet Venus was on the opposite side of the sky (in the east) with the Sun sited directly between these two equally bright objects, as documented in East-Asian records. Here, we investigate the engravings on tombstones (ste\’cci) from several necropolises in present-day Bosnia and Herzegovina (far from the influence of the Church) as a possible European ‘record’ of SN 1054. Certainly, knowledge and understanding of celestial events (such as supernovae) were somewhat poor in the mid-XI century.

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M. Filipović, M. Ilić, T. Jarrett, et. al.
Thu, 6 May 21
5/55

Comments: 10 pages, 5 figures, accepted for publication in European Journal of Science and Theology

A Historical Perspective on the Diversity of Explanations for New Classes of Transient and VariableStars [SSA]

Posted on by

http://arxiv.org/abs/2104.11104


As new classes of transients and variable stars are discovered, and theoretical models are established to work or not to work for a few members of the class, it is often the case that some researchers will make arguments on the basis of Occam’s razor that all members of the class must be produced by whichever mechanism first successfully explained one of the objects. It is also frequent that this assumption will be more more implicitly. Retrospective analysis shows rather clearly that this argument fails a large fraction of the time, and in many cases, this search for false consistency has led to more fundamental astrophysical errors, a few of which are quite prominent in the history of astronomy. A corollary of this is that on numerous occasions, theoretical models to explain transients have turned out to be models that describe real (but often not yet discovered) phenomenona other than the ones to which they have first been applied, albeit with minor errors that caused the model to appear to fit to a known phenomenon it did not describe. A set of examples of such events is presented here (some of which will be quite familiar to most astronomers), along with a discussion of why this phenomenon occurs, how it may be manifesting itself at the present time. Some discussion will also be made of why and when survey designs have led to immediate separation of various transient mechanisms, generally by being overpowered in some way relative to what is needed to {\it detect} a new class of objects.

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T. Maccarone
Fri, 23 Apr 2021
32/48

Comments: 9 pages, accepted to Journal of the American Association of Variable Star Observers

Comprendre l atmosphere du Soleil et celles des etoiles variables a la fin du 19e siecle or, Understanding the Sun and variable stars atmospheres at the end of the 19th Century [CL]

Posted on by

http://arxiv.org/abs/2104.10043


Guy Boistel questions the Sun / variable stars analogy at the heart of the work of Dutch astronomer Albert Brester. The problem of interdisciplinarity appears in the objectification of the Sun at the end of the 19th century: it is by mixing astronomy, physics and chemistry that Brester tried to apply knowledge of the solar atmosphere to the understanding of variable stars, a fairly confidential field of study still at that time.

Read this paper on arXiv…

G. Boistel
Wed, 21 Apr 2021
34/72

Comments: 28 pages, in French, 6 figures, a chronobibliography of Albert Brester’s works

From Lacaille to Lalande. French works on lunar distances, nautical ephemerides and lunar tables, 1742-1785 [SSA]

Posted on by

http://arxiv.org/abs/2104.01916


The papers studies the highly misknown works of french astronomers on ephemerides and lunar distances on the period 1742-1785. These works will have a strong influence on the development of the Nautical Almanac by Nevil Maskelyne in 1766-1767.

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G. Boistel
Tue, 6 Apr 2021
31/55

Comments: 24 pages, text in english, no figures

Nouvelle theorie des taches du Soleil, by E. Pezenas (1692-1776). A fully annoted edition of a manuscript [CL]

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http://arxiv.org/abs/2104.00002


The manuscript New Theory of Sunspots was identified and attributed to the Jesuit astronomer and hydrographer from Marseille Esprit Pezenas (1692-1776) during the year 2002, during the systematic search for papers concerning him in the various French funds. The manuscript, in large part unpublished, New Theory of Sunspots was written by astronomer and professor of Marseilles Jesuit hydrography, Father Esprit Pezenas (1692-1776). The text was composed and revised between the years 1766 and 1772. In this manuscript, of which we are going to study the conditions of its composition, P. Pezenas gives one of the last geometric methods, related graphical methods, allowing the inclination of the Sun’s equator to be deduced on ecliptic, using three observations of a sunspot, at given times, and in taking into account the movement of the Earth with respect to the Sun during the duration of observations. This text contains all the digital elements allowing to follow and understand the application of geometric processing methods of observations and observation techniques mentioned above in the introduction: passages of edges and Sun spots at the meridian, use of objective micrometers and wire micrometers. At detour of his calculations, Father Pezenas announces a duration of about 26 days and 9 hours for the rotation of the Sun around its axis, comments on and corrects some observation data published in Le Monnier’s Heavenly History.

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E. Pezenas and G. Boistel
Fri, 2 Apr 2021
55/55

Comments: 10 pages, in French, 1 figure

Science Spoofs, Physics Pranks and Astronomical Antics [CL]

Posted on by

http://arxiv.org/abs/2103.17057


Some scientists take themselves and their work very seriously. However, there are plenty of examples of humour being combined with science. Here I review some examples from the broad fields of Physics and Astronomy, particularly focusing on practical jokes and parodies.

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D. Scott
Thu, 1 Apr 2021
34/71

Comments: 14 pages, no figures

Where was Mean Solar Time first adopted? [CL]

Posted on by

http://arxiv.org/abs/2103.07694


It is usually stated in the literature that Geneva was the first city to adopt mean solar time, in 1780, followed by London (or the whole of England) in 1792, Berlin in 1810 and Paris in 1816. In this short note I partially revise this statement, using primary references when available, and provide dates for a few other European cities. Though no exact date was found for the first public use of mean time, the primacy seems to belong to England, followed by Geneva in 1778-79 (for horologists), Berlin in 1810, Geneva in 1821 (for public clocks), Vienna in 1823, Paris in 1826, Rome in 1847, Turin in 1849, Milan, Bologna and Florence in 1860.

Read this paper on arXiv…

S. Bianchi
Tue, 16 Mar 21
42/92

Comments: 5 pages. Accepted by JAHH. Comments and references to the adoption of mean time in other cities/countries are welcomed

Testing Galaxy Formation and Dark Matter with Low Surface Brightness Galaxies [GA]

Posted on by

http://arxiv.org/abs/2103.05003


Galaxies are the basic structural element of the universe; galaxy formation theory seeks to explain how these structures came to be. I trace some of the foundational ideas in galaxy formation, with emphasis on the need for non-baryonic cold dark matter. Many elements of early theory did not survive contact with observations of low surface brightness galaxies, leading to the need for auxiliary hypotheses like feedback. The failure points often trace to the surprising predictive successes of an alternative to dark matter, the Modified Newtonian Dynamics (MOND). While dark matter models are flexible in accommodating observations, they do not provide the predictive capacity of MOND. If the universe is made of cold dark matter, why does MOND get any predictions right?

Read this paper on arXiv…

S. McGaugh
Wed, 10 Mar 21
36/56

Comments: 29 pages (plus 20 pages of references), 8 figures. Invited review for a conference on Dark Matter and Modified Gravity, part of the project `LHC and Gravity’. Includes an introduction accessible to a broad audience and some historical narrative leading to more advanced material

Joshua's Total Solar Eclipse at Gibeon [CL]

Posted on by

http://arxiv.org/abs/2102.09402


We reanalyse the solar eclipse linked to the Biblical passage about the military leader Joshua who ordered the sun to halt in the midst of the day (Joshua 10:12). Although there is agreement that the basic story is rooted in a real event, the date is subject to different opinions. We review the historical emergence of the text and confirm that the total eclipse of the sun of 30 September 1131 BCE is the most likely candidate. The Besselian Elements for this eclipse are re-computed. The error for the deceleration parameter of Earth’s rotation, $\Delta T$, is improved by a factor of 2.

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E. Khalisi
Fri, 19 Feb 21
64/64

Comments: 6 pages, 2 figures, 2 tables

Spacetime singularities and a novel formulation of indeterminism [CL]

Posted on by

http://arxiv.org/abs/2101.10887


Spacetime singularities in general relativity are commonly thought to be problematic, in that they signal a breakdown in the theory. We address the question of how to interpret this breakdown, restricting our attention to classical considerations (though our work has ramifications for more general classical metric theories of gravity, as well). In particular, we argue for a new claim: spacetime singularities in general relativity signal indeterminism.
The usual manner in which indeterminism is formulated for physical theories can be traced back to Laplace. This formulation is based on the non-uniqueness of future (or past) states of a physical system — as understood in the context of a physical theory — as a result of the specification of an antecedent state (or, respectively, of a subsequent state). We contend that for physical theories generally, this formulation does not comprehensively capture the relevant sense of a lack of determination. And, in particular, it does not comprehensively capture the sense(s) in which a lack of determination (and so, indeterminism) arises due to spacetime singularities in general relativity.
We thus present a novel, broader formulation, in which indeterminism in the context of some physical theory arises whenever one of the three following conditions holds: future (and/or past) states are (i) not unique — as for Laplacian notions of indeterminism; (ii) not specified; or (iii) `incoherent’ — that is, they fail to satisfy certain desiderata that are internal to the theory and/or imposed from outside the theory. We apply this formulation to salient features of singularities in general relativity and show that this broader sense of indeterminism can comprehensively account for (our interpretation of) the breakdown signaled by their occurrence.

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F. Azhar and M. Namjoo
Wed, 3 Feb 21
31/61

Comments: 16 pages, 1 figure, 1 table

ASTROMOVES: Astrophysics, Diversity, Mobility [CL]

Posted on by

http://arxiv.org/abs/2101.10826


The US astronomy/astrophysics community comes together to create a decadal report that summarizes grant funding priorities, observatory & instrumental priorities as well as community accomplishments and community goals such as increasing the number of women and the number of people from underrepresented groups. In the 2010 US National Academies Decadal Survey of Astronomy (National Research Council, 2010), it was suggested that having to move so frequently which is a career necessity may be unattractive to people wanting to start a family, especially impacting women. Whether in Europe or elsewhere, as postdocs, astrophysicists will relocate every two to three years, until they secure a permanent position or leave research altogether. Astrophysicists do perceive working abroad as important and positive for their careers (Parenti, 2002); however, it was found that the men at equal rank had not had to spend as much time abroad to further their careers (Fohlmeister & Helling, 2012). By implication, women need to work abroad longer or have more positions abroad to achieve the same rank as men. Astrophysicists living in the United Kingdom prefer to work in their country of origin, but many did not do so because of worse working conditions or difficultly finding a job for their spouse (Fohlmeister & Helling, 2014). In sum, mobility and moving is necessary for a career in astrophysics, and even more necessary for women, but astrophysicists prefer not to move as frequently as needed to maintain a research career. To gather more data on these issues and to broaden the discourse beyond male/female to include the gender diverse as well as to include other forms of diversity, I designed the ASTROMOVES project which is funded through a Marie Curie Individual Fellowship. Though slowed down by COVID-19, several interviews have been conducted and some preliminary results will be presented.

Read this paper on arXiv…

J. Holbrook
Wed, 27 Jan 21
16/68

Comments: 9 pages

Comet 12P/Pons-Brooks: Identification with Comets C/1385 U1 and C/1457 A1 [EPA]

Posted on by

http://arxiv.org/abs/2012.15583


Comet 12P/Pons-Brooks is an intermediate-period comet (orbital period around 71 years) comparable to 1P/Halley. The comet was seen first in 1812, and then again in 1883 and 1954. The comet was recovered in 2020 an will pass its perihelion passage 2024. We report the unambiguous identification of this comet with the historic comets C/1385 U1 and C/1457 A1; we were able to link both historic apparitions with 12P. The link is also supported by the historic descriptions of its appearance and brightness. Further, we discuss other historical comets for possible relationships with 12P and identify a comet seen in 245 as a probable earliest recorded sighting of 12P/Pons-Brooks.

Read this paper on arXiv…

M. Meyer, T. Kobayashi, S. Nakano, et. al.
Fri, 1 Jan 21
16/103

Comments: Submitted and to be published in the International Comet Quarterly, 16 pages, 6 figures

Comet 12P/Pons-Brooks: Identification with Comets C/1385 U1 and C/1457 A1 [EPA]

Posted on by

http://arxiv.org/abs/2012.15583


Comet 12P/Pons-Brooks is an intermediate-period comet (orbital period around 71 years) comparable to 1P/Halley. The comet was seen first in 1812, and then again in 1883 and 1954. The comet was recovered in 2020 an will pass its perihelion passage 2024. We report the unambiguous identification of this comet with the historic comets C/1385 U1 and C/1457 A1; we were able to link both historic apparitions with 12P. The link is also supported by the historic descriptions of its appearance and brightness. Further, we discuss other historical comets for possible relationships with 12P and identify a comet seen in 245 as a probable earliest recorded sighting of 12P/Pons-Brooks.

Read this paper on arXiv…

M. Meyer, T. Kobayashi, S. Nakano, et. al.
Fri, 1 Jan 21
95/103

Comments: Submitted and to be published in the International Comet Quarterly, 16 pages, 6 figures

The Dalton Minimum and John Dalton's Auroral Observations [SSA]

Posted on by

http://arxiv.org/abs/2012.13713


In addition to the regular Schwabe cycles of approximately 11 y, “prolonged solar activity minima” have been identified through the direct observation of sunspots and aurorae, as well as proxy data of cosmogenic isotopes. Some of these minima have been regarded as grand solar minima, which are arguably associated with the special state of the solar dynamo and have attracted significant scientific interest. In this paper, we review how these prolonged solar activity minima have been identified. In particular, we focus on the Dalton Minimum, which is named after John Dalton. We review Dalton’s scientific achievements, particularly in geophysics. Special emphasis is placed on his lifelong observations of auroral displays over approximately five decades in Great Britain. Dalton’s observations for the auroral frequency allowed him to notice the scarcity of auroral displays in the early 19th century. We analyze temporal variations in the annual frequency of such displays from a modern perspective. The contemporary geomagnetic positions of Dalton’s observational site make his dataset extremely valuable because his site is located in the sub-auroral zone and is relatively sensitive to minor enhancements in solar eruptions and solar wind streams. His data indicate clear solar cycles in the early 19th century and their significant depression from 1798 to 1824. Additionally, his data reveal a significant spike in auroral frequency in 1797, which chronologically coincides with the “lost cycle” that is believed to have occurred at the end of Solar Cycle 4. Therefore, John Dalton’s achievements can still benefit modern science and help us improve our understanding of the Dalton Minimum.

Read this paper on arXiv…

S. Silverman and H. Hayakawa
Tue, 29 Dec 20
37/66

Comments: 19 pages, 3 figures, accepted for publication in the JSWSC on 26 Dec 2020

The Dalton Minimum and John Dalton's Auroral Observations [SSA]

Posted on by

http://arxiv.org/abs/2012.13713


In addition to the regular Schwabe cycles of approximately 11 y, “prolonged solar activity minima” have been identified through the direct observation of sunspots and aurorae, as well as proxy data of cosmogenic isotopes. Some of these minima have been regarded as grand solar minima, which are arguably associated with the special state of the solar dynamo and have attracted significant scientific interest. In this paper, we review how these prolonged solar activity minima have been identified. In particular, we focus on the Dalton Minimum, which is named after John Dalton. We review Dalton’s scientific achievements, particularly in geophysics. Special emphasis is placed on his lifelong observations of auroral displays over approximately five decades in Great Britain. Dalton’s observations for the auroral frequency allowed him to notice the scarcity of auroral displays in the early 19th century. We analyze temporal variations in the annual frequency of such displays from a modern perspective. The contemporary geomagnetic positions of Dalton’s observational site make his dataset extremely valuable because his site is located in the sub-auroral zone and is relatively sensitive to minor enhancements in solar eruptions and solar wind streams. His data indicate clear solar cycles in the early 19th century and their significant depression from 1798 to 1824. Additionally, his data reveal a significant spike in auroral frequency in 1797, which chronologically coincides with the “lost cycle” that is believed to have occurred at the end of Solar Cycle 4. Therefore, John Dalton’s achievements can still benefit modern science and help us improve our understanding of the Dalton Minimum.

Read this paper on arXiv…

S. Silverman and H. Hayakawa
Tue, 29 Dec 20
29/66

Comments: 19 pages, 3 figures, accepted for publication in the JSWSC on 26 Dec 2020

The Dalton Minimum and John Dalton's Auroral Observations [SSA]

Posted on by

http://arxiv.org/abs/2012.13713


In addition to the regular Schwabe cycles of approximately 11 y, “prolonged solar activity minima” have been identified through the direct observation of sunspots and aurorae, as well as proxy data of cosmogenic isotopes. Some of these minima have been regarded as grand solar minima, which are arguably associated with the special state of the solar dynamo and have attracted significant scientific interest. In this paper, we review how these prolonged solar activity minima have been identified. In particular, we focus on the Dalton Minimum, which is named after John Dalton. We review Dalton’s scientific achievements, particularly in geophysics. Special emphasis is placed on his lifelong observations of auroral displays over approximately five decades in Great Britain. Dalton’s observations for the auroral frequency allowed him to notice the scarcity of auroral displays in the early 19th century. We analyze temporal variations in the annual frequency of such displays from a modern perspective. The contemporary geomagnetic positions of Dalton’s observational site make his dataset extremely valuable because his site is located in the sub-auroral zone and is relatively sensitive to minor enhancements in solar eruptions and solar wind streams. His data indicate clear solar cycles in the early 19th century and their significant depression from 1798 to 1824. Additionally, his data reveal a significant spike in auroral frequency in 1797, which chronologically coincides with the “lost cycle” that is believed to have occurred at the end of Solar Cycle 4. Therefore, John Dalton’s achievements can still benefit modern science and help us improve our understanding of the Dalton Minimum.

Read this paper on arXiv…

S. Silverman and H. Hayakawa
Tue, 29 Dec 20
14/66

Comments: 19 pages, 3 figures, accepted for publication in the JSWSC on 26 Dec 2020

M.K. Das Gupta, the first Indian radio astronomer, and his connection with the 2020 Physics Nobel Prize [CL]

Posted on by

http://arxiv.org/abs/2012.01001


Half of the 2020 Nobel Prize is awarded for discovering a super-massive black hole at the centre of our Galaxy. One of the first indications of the existence of a black hole at the centre of a galaxy was found by Jennison and Das Gupta in 1953 while carrying on a radio observation of the source Cygnus A. Mrinal Das Gupta, who was doing his PhD at Manchester University at the time of this discovery, spent the major part of his professional career at Calcutta University. We give an outline of Das Gupta’s life and explain the scientific significance of his discovery.

Read this paper on arXiv…

A. Choudhuri and R. Chatterjee
Thu, 3 Dec 20
22/81

Comments: Invited paper submitted to Science and Culture

Cometary records revise Eastern Mediterranean chronology around 1240 CE [CL]

Posted on by

http://arxiv.org/abs/2012.00976


Eirene Laskarina, empress of John III Batatzes of the exiled Byzantine Empire of Nicaea (1204–1261 CE), was an important Eastern Mediterranean figure in the first half of the thirteenth century. We reassess the date of Eirene’s death, which has been variously dated between late 1239 and 1241, with the understanding that narrowing the range in which this event occurred contributes much to understanding the political situation in the area around 1240. George Akropolites, a famous official of the Empire, gives an account that connects Eirene’s death to a comet that appeared “six months earlier”, thus pointing to two comet candidates that were visible from the Eastern Mediterranean between 1239 and 1241, one recorded on “3 June 1239” and the other on “31 January 1240”. Recent historians prefer the former, based on historical circumstances and without a critical assessment of the comet records. We revisit the historical records and reveal that the “3 June 1239” candidate was not a comet. On the other hand, the other candidate, sighted on “31 January 1240”, was a comet, as supported by multiple historical records in multiple regions, and is also a good fit with Akropolites’s narrative. Therefore, we conclude that Eirene died six months after the comet that was seen on 31 January 1240, which places her death in the summer of 1240. Given that the date of her death is crucial for determining some other contemporary events across the Eastern Mediterranean, our results offer a solid basis for further research on the thirteenth-century Eastern Mediterranean.

Read this paper on arXiv…

K. Murata, K. Ichikawa, Y. Fujii, et. al.
Thu, 3 Dec 20
29/81

Comments: 14 pages, 3 figures, accepted for publication in PASJ

José Monteiro da Rocha (1734-1819) and his work of 1782 on the determination of comet orbits [CL]

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http://arxiv.org/abs/2012.00753


In 1782 Jos\’e Monteiro da Rocha, astronomer and professor of the University of Coimbra, presented in a public session of the Royal Academy of Sciences of Lisbon a memoir on the problem of the determination of the comets’ orbits. Only in 1799, the “Determina\c{c}\~ao das Orbitas dos Cometas” (Determination of the orbits of comets) would be published in the Academy’s memoires. In that work, Monteiro da Rocha presents a method for solving the problem of the determination of the parabolic orbit of a comet from three observations. Monteiro da Rocha’s method is essentially the same method proposed by Olbers and published under von Zach’s sponsorship two years before, in 1797. To have been written and published in Portuguese was certainly a hindrance for its dissemination among the international astronomical community. In this article, we intend to present Monteiro da Rocha’s method and trying to see to what extent Gomes Teixeira’s assertion (Teixeira 1934) that Monteiro da Rocha and Olbers must figure together in the history of astronomy, as the first inventors of a practical and easy method for the determination of parabolic orbits of comets, is justified.

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F. Figueiredo and J. Fernandes
Thu, 3 Dec 20
39/81

Comments: Accepted in Journal for the History of Astronomy

La polémica del multiverso [CL]

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http://arxiv.org/abs/2009.06428


This paper offers a synthesis of the positions in the literature regarding controversies about the multiverse. After reviewing some simple elements of modern cosmology and its observational limitations, we will present the history of the ideas that led, first, to the proposal of the anthropic principle and, years later, to the possible existence of causally disconnected domains, eventually endowed with their own laws and fundamental constants, not all compatible with the existence of observers, which were globally baptized with the confusing name of parallel universes or multiverse.

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A. Gangui
Tue, 15 Sep 20
-1567/97

Comments: in Spanish

A history of the Magellanic Clouds and the European exploration of the Southern Hemisphere [CL]

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http://arxiv.org/abs/2009.04973


The Magellanic Clouds were known before Magellan’s voyage exactly 500 years ago, and were not given that name by Magellan himself or his chronicler Antonio Pigafetta. They were, of course, already known by local populations in South America, such as the Mapuche and Tupi-Guaranis. The Portuguese called them Clouds of the Cape, and scientific circles had long used the name of Nubecula Minor and Major. We trace how and when the name Magellanic Clouds came into common usage by following the history of exploration of the southern hemisphere and the southern sky by European explorers. While the name of Magellan was quickly associated to the Strait he discovered (within about 20 years only), the Clouds got their final scientific name only at the end of the 19th century, when scientists finally abandoned Latin as their communication language.

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M. Dennefeld
Fri, 11 Sep 20
-1533/48

Comments: 20 pages, 9 figures. To appear (in slightly abbreviated form) in the ESO Messenger

The Solar Eclipses of the Pharaoh Akhenaten [CL]

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http://arxiv.org/abs/2004.12952


We suggest an earlier date for the accession of the pharaoh Akhenaten of the New Kingdom in Egypt. His first year of reign would be placed in 1382 BCE. This conjecture is based on the possible witness of three annular eclipses of the sun during his lifetime: in 1399, 1389, and 1378 BCE. They would explain the motive for his worship of the sun that left its mark on later religious communities. Evidence from Akhenaten’s era is scarce, though some lateral dependencies can be disentangled on implementing the historical course of the subsequent events.

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E. Khalisi
Fri, 4 Sep 20
-1402/65

Comments: 7 pages, 3 figs, 2 tabs; overhauled and improved version

Clusters of Solar Eclipses in the Maori Era [CL]

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http://arxiv.org/abs/2009.01663


A dozen of high-magnitude solar eclipses accumulated near New Zealand in the 15th century AD when the Maori inhabited the two main islands. Taking today’s capital Wellington as the point of reference, we counted ten events with magnitude larger than 0.9 between 1409 and 1516 AD and two more just below this value. The eclipses need not have been all observed on account of weather conditions. An allusion to a particular event that could be conveyed in a myth is discussed, but the dating turns out far from certain. We take the opportunity here to meet the astronomy of the Maori and their understanding of this natural phenomenon. Moreover, an announcement is made to a cluster of five central eclipses of the sun that will encounter New Zealand from 2035 to 2045.

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E. Khalisi
Fri, 4 Sep 20
-1400/65

Comments: 7 pages, 5 figs, 1 tab, 13 refs

Eclipses in the Aztec Codices [CL]

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http://arxiv.org/abs/2008.08982


This paper centers on the collection of accounts on solar eclipses from the era of the Aztecs in Mesoamerica, about 1300 to 1550 AD. We present a list of all eclipse events complying with the topological visibility from the capital Tenochtitlan. Forty records of 23 eclipses entered the various Aztec manuscripts (codices), usually those of large magnitude. Each event is discussed with regard to its historical context, as we try to comprehend the importance the Aztecs gave to the phenomenon. It seems that this culture paid noticeably less attention to eclipses than the civilisations in the “Old World”. People did not understand the cause of it and did not care as much about astronomy as in Babylonia and ancient China. Furthermore, we discuss the legend on the comet of Moctezuma II. It turns out that the post-conquest writers misconceived what the sighting was meant to be.

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E. Khalisi
Fri, 21 Aug 20
-1145/51

Comments: 15 pages, 10 figs, 2 tabs, 25 refs

Accuracy of magnitudes in pre-telescopic star catalogues [IMA]

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http://arxiv.org/abs/2008.04967


Historical star magnitudes from catalogues by Ptolemy (137 AD), as-Sufi (964) and Tycho Brahe (1602/27) are converted to the Johnson V-mag scale and compared to modern day values from the HIPPARCOS catalogue. The deviations (or “errors”) are tested for dependencies on three different observational influences. The relation between historical and modern magnitudes is found to be linear in all three catalogues as it had previously been shown for the Almagest data by Hearnshaw (1999). A slight dependency on the colour index (B-V) is shown throughout the data sets and as-Sufi’s as well as Brahe’s data also give fainter values for stars of lower culmination height (indicating extinction). In all three catalogues, a star’s estimated magnitude is influenced by the brightness of its immediate surroundings. After correction for the three effects, the remaining variance within the magnitude errors can be considered as approximate accuracy of the pre-telescopic magnitude estimates. The final converted and corrected magnitudes are available via the Vizier catalogue access tool (Ochsenbein, Bauer, & Marcout, 2000).

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P. Protte and S. Hoffmann
Thu, 13 Aug 20
-920/67

Comments: 13 pages, 9 figures

Donald Lynden-Bell: A Biographical Memoir [CL]

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http://arxiv.org/abs/2007.09474


Donald Lynden-Bell’s many contributions to astrophysics encompass general relativity, galactic dynamics, telescope design and observational astronomy. In the 1960s, his papers on stellar dynamics led to fundamental insights into the equilibria of elliptical galaxies, the growth of spiral patterns in disc galaxies and the stability of differentially rotating, self-gravitating flows. Donald introduced the ideas of violent relaxation' andthe gravothermal catastrophe’ in pioneering work on the thermodynamics of galaxies and negative heat capacities. He shared the inaugural Kavli Prize in Astrophysics in 2008 for his contributions to our understanding of quasars. His prediction that dead quasars or supermassive black holes may reside in the nuclei of nearby galaxies has been confirmed by multiple pieces of independent evidence. His work on accretion discs led to new insights into their workings, as well as the realisation that the infrared excess in T Tauri stars was caused by protostellar discs around these young stars. He introduced the influential idea of monolithic collapse of a gas cloud as a formation mechanism for the Milky Way Galaxy. As this gave way to modern ideas of merging and accretion as drivers of galaxy formation, Donald was the first to realise the importance of tidal streams as measures of the past history and present day gravity field of the Galaxy. Though primarily a theorist, Donald participated in one of the first observational programs to measure the large-scale streaming of nearby galaxies. This led to the discovery of the `Great Attractor’. The depth and versatility of his contributions mark Donald out as one of the most influential and pre-eminent astronomers of his day.

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N. Evans
Tue, 21 Jul 20
-374/75

Comments: To appear, Biographical Memoirs of Fellows of the Royal Society

Short story of stratospheric and ground-based observations of solar photosphere with high angular resolution in the 70s of the XX century at the Pulkovo Observatory [IMA]

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http://arxiv.org/abs/2007.00348


In the 70s of the last century, the stratospheric solar observatory “Saturn” with a 100cm telescope was launched at Pulkovo Observatory. The photographs and spectra obtained on it for more than 45 years remained record-breaking in angular resolution. Then, for ground-based observations of Sun fine structure in Pamir at an altitude of 4.5 km, a 50 cm open-type Pulkovo mobile telescope was installed. Photographs and spectra obtained with the Saturn telescope for the visible range were an important step in the development of high spatial resolution technologies in heliophysics. However, to date, the details of these studies remain unknown to the global scientific community. In this paper, an attempt is made to partially fill this gap.

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L. L.D.Parfinenko
Thu, 2 Jul 20
4/64

Comments: N/A

Counterparts of Far Eastern Guest Stars: Novae, supernovae, or something else? [SSA]

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http://arxiv.org/abs/2006.00977


Historical observations of transients are crucial for studies of their long-term evolution. This paper forms part of a series of papers in which we develop methods for the analysis of ancient data of transient events and their usability in modern science. Prior research on this subject by other authors has focused on looking for historical supernovae and our earlier work focused on cataclysmic binaries as classical novae. In this study we consider planetary nebulae, symbiotic stars, supernova remnants and pulsars in the search fields of our test sample. We present the possibilities for these object types to flare up visually, give a global overview on their distribution and discuss the objects in our search fields individually. To summarise our results, we provide a table of the most likely identifications of the historical sightings in our test sample and outline our method in order to apply it to further historical records in future works. Highlights of our results include a re-interpretation of two separate sightings as one supernova observation from May 667 to June 668 CE, the remnant of which could possibly be SNR G160.9+02.6. We also suggest the recurrent nova U Sco as a candidate for the appearance observed between Scorpius and Ophiuchus in 891, which could point towards a long-term variability of eruption amplitudes. In addition, we find that the `shiny bright’ sighting in 1431 can be linked to the symbiotic binary KT Eri, which erupted as a naked eye classical nova in 2009.

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S. Hoffmann, N. Vogt and O. Lux
Tue, 2 Jun 20
6/90

Comments: 19 pages, 4 figures inline, online-only appendices with 47 figures

The October 10, 1912 solar eclipse expeditions and the first attempt to measure light-bending by the Sun [CL]

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http://arxiv.org/abs/2004.02026


In 1911 Einstein proposed that light-bending by the Sun’s gravitational field could be measured during a total solar eclipse. The first opportunity in which this measurement would be tried, was during the total solar eclipse of October 10, 1912. We report about the expeditions sent to Brazil to observe this eclipse, including the one from the C\’ordoba Observatory, from Argentina, which aimed to measure this Einstein’s effect.

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L. Crispino
Fri, 8 May 20
37/72

Comments: 23 pages, 29 figures, Contribution to Selected Papers of the Fifth Amazonian Symposium on Physics, to be published in IJMPD

The first attempts to measure light deflection by the Sun [CL]

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http://arxiv.org/abs/2004.11681


Soon after Einstein’s calculation of the effect of the Sun’s gravitational field on the propagation of light in 1911, astronomers around the world tried to measure and verify the value. If the first attempts in Brazil in 1912 or Imperial Russia in 1914 had been successful, they would have proven Einstein wrong.

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L. Crispino and S. Paolantonio
Thu, 30 Apr 20
39/71

Comments: 8 pages, 8 figures

What's in a name: the etymology of astrobiology [CL]

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http://arxiv.org/abs/2004.11312


Astrobiology has been gaining increasing scientific prominence and public attention as the search for life beyond Earth continues to make significant headway on multiple fronts. In view of these recent developments, the fascinating and dynamic etymology of astrobiology is elucidated, and thus shown to encompass a plethora of vivid characters drawn from different continents, religions, ideologies and centuries.

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M. Lingam and A. Loeb
Fri, 24 Apr 20
47/63

Comments: 9 pages; 0 figures

John Couch Adams: mathematical astronomer, college friend of George Gabriel Stokes and promotor of women in astronomy [CL]

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http://arxiv.org/abs/2004.03886


John Couch Adams predicted the location of Neptune in the sky, calculated the expectation of the change in the mean motion of the Moon due to the Earth’s pull, and determined the origin and the orbit of the Leonids meteor shower which had puzzled astronomers for almost a thousand years. With his achievements Adams can be compared with his good friend George Stokes. Not only were they born in the same year, but were also both senior wranglers, received the Smith’s Prizes and Copley medals, lived, thought and researched at Pembroke College, and shared an appreciation of Newton. On the other hand, Adams’ prediction of Neptune’s location had absolutely no influence on its discovery in Berlin. His lunar theory did not offer a physical explanation for the Moon’s motion. The origin of the Leonids was explained by others before him. Adams refused a knighthood and an appointment as Astronomer Royal. He was reluctant and slow to publish, but loved to derive the values of logarithms to 263 decimal places. The maths and calculations at which he so excelled mark one of the high points of celestial mechanics, but are rarely taught nowadays in undergraduate courses. The differences and similarities between Adams and Stokes could not be more striking. This volume attests to the lasting legacy of Stokes’ scientific work. What is then Adams’ legacy? In this contribution I will outline Adams’ life, instances when Stokes’ and Adams’ lives touched the most, his scientific achievements and a usually overlooked legacy: female higher education and support of a woman astronomer.

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D. Krajnović
Thu, 9 Apr 20
52/54

Comments: 17 pages, 1 figure; accepted for publication in “Stokes at 200” issue of Philosophical Transactions A, guest edited by Silvana Cardoso, Julyan Cartwright, Herbert Huppert and Christopher Ness

Urban Planning in the First Unfortified Spanish Colonial Town: The orientation of the historic churches of San Cristobal de La Laguna [CL]

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http://arxiv.org/abs/2003.12410


The city of San Cristobal de La Laguna in the Canary Island of Tenerife (Spain) has an exceptional value due to the original conception of its plan. It is an urban system in a grid, outlined by straight streets that form squares, its layout being the first case of an unfortified colonial city with a regular plan in the overseas European expansion. It constitutes a historical example of the so-called “Town of Peace”, the archetype of a city-republic in a new land that employed its own natural boundaries to delimit and defend itself. Founded in 1496, the historical centre of the old city was declared a World Heritage Site by UNESCO in 1999. We analyse the exact spatial orientation of twenty-one historic Christian churches currently existing in the old part of La Laguna which we take as a good indicator of the original layout of the urban lattice. We find a clear orientation pattern that, if correlated with the rising or setting Sun, singles out an absolute-value astronomical declination slightly below 20 degrees, which, within the margin of error of our study, might be associated with the July 25th feast-day of San Cristobal de Licia, the saint to whom the town was originally dedicated. We also discuss at some length some recent proposals which invoke somewhat far-fetched hypotheses for the planimetry of the old city and finish up with some comments on one of its outstanding features, namely its Latin-cross structure, which is apparent in the combined layout of some of its most emblematic churches.

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A. Gangui and J. Belmonte
Mon, 30 Mar 20
41/44

Comments: PDF document including 1 table and 8 figures

Extreme Space Weather Events Recorded in History [CL]

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http://arxiv.org/abs/2003.06020


This section shows an overview of a recent development of the studies on great space weather events in history. Its discussion starts from the Carrington event and compare its intensity with the extreme storms within the coverage of the regular magnetic measurements. Extending its analyses back beyond their onset, this section shows several case studies of extreme storms with sunspot records in the telescopic observations and candidate auroral records in historical records. Before the onset of telescopic observations, this section shows the chronological coverages of the records of unaided-eye sunspot and candidate aurorae and several case studies on their basis.

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H. Hayakawa and Y. Ebihara
Mon, 16 Mar 20
36/57

Comments: 19 pages, 8 figures, written in Japanese, a Japanese article for a part of the Solar-Terrestrial Environment Prediction, in press

Provenance of the Cross Sign of 806 in the Anglo-Saxon Chronicle: A possible Lunar Halo over Continental Europe? [CL]

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http://arxiv.org/abs/2003.04192


While graphical records of astronomical/meteorological events before telescopic observations are of particular interest, they have frequently undergone multiple copying and may have been modified from the original. Here, we analyze a graphical record of the cross-sign of 806 CE in the Anglo-Saxon Chronicle, which has been considered one of the earliest datable halo drawings in British records, whereas another cross-sign in 776 CE has been associated with the aurora. However, philological studies have revealed the later 806 event is derived from Continental annals. Here, records and drawings for the 806 event have been philologically traced back to mid-9th Century Continental manuscripts and the probable observational site identified as the area of Sens in northern France. The possible lunar halos at that time have been comprehensively examined by numerical ray tracing. Combined with calculations of twilight sky brightness, they identify a visibility window supporting monastic observation. Cruciform halos are shown to be fainter and rarer than brighter and more commonplace lunar halos. Physically credible cloud ice crystal variations can reproduce all the manuscript renditions. The manuscript records prove less than desirable detail but what is presented is fully consistent with a lunar halo interpretation. Finally, the possible societal impacts of such celestial events have been mentioned in the context of contemporary coins in Anglo-Saxon England and the Carolingian Empire. These analyses show that we need to trace their provenance back as far as possible, to best reconstruct the original event, even if graphical records are available for given astronomical/meteorological events.

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Y. Uchikawa, L. Cowley, H. Hayakawa, et. al.
Tue, 10 Mar 20
46/63

Comments: 23 pages, 7 figures, and 1 table; accepted for publication in the HGSS; Figures 1 and 3 is available only in the record version