The Early Scientific Contributions of J. Robert Oppenheimer: Why Did the Scientific Community Miss the Black Hole Opportunity? [CL]

We aim to carry out an assessment of the scientific value of Oppenheimer’s research on black holes in order to determine and weigh possible factors to explain its neglect by the scientific community, and even by Oppenheimer himself. Dealing primarily with the science and looking closely at the scientific culture and the scientific conceptual belief system of the 1930s, the present article seeks to supplement the existent literature on the subject by enriching the explanations and possibly complicating the guiding questions. We suggest a rereading of Oppenheimer as a more intriguing, ahead-of-his-time figure.

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M. Ortega-Rodriguez, H. Solis-Sanchez, E. Boza-Oviedo, et. al.
Tue, 14 Mar 17

Comments: 19 pages, Phys. Perspect. (2017)

Cosmology and Convention [CL]

I argue that some important elements of the current cosmological model are “conventionalist” in the sense defined by Karl Popper.

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D. Merritt
Wed, 8 Mar 17

Comments: N/A

Fifty years of cosmological particle creation [CL]

In the early sixties Leonard Parker discovered that the expansion of the universe can create particles out of the vacuum, opening a new and fruitfull field in physics. We give a historical review in the form of an interview that took place during the Conference ERE2014 (Valencia 1-5, September, 2014).

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L. Parker and J. Navarro-Salas
Fri, 24 Feb 17

Comments: 8 pages

Why Boltzmann Brains Are Bad [CL]

Some modern cosmological models predict the appearance of Boltzmann Brains: observers who randomly fluctuate out of a thermal bath rather than naturally evolving from a low-entropy Big Bang. A theory in which most observers are of the Boltzmann Brain type is generally thought to be unacceptable, although opinions differ. I argue that such theories are indeed unacceptable: the real problem is with fluctuations into observers who are locally identical to ordinary observers, and their existence cannot be swept under the rug by a choice of probability distributions over observers. The issue is not that the existence of such observers is ruled out by data, but that the theories that predict them are cognitively unstable: they cannot simultaneously be true and justifiably believed.

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S. Carroll
Mon, 6 Feb 17

Comments: 27 pages. Invited submission to a volume on Current Controversies in Philosophy of Science, eds. Shamik Dasgupta and Brad Weslake

Einstein's 1917 Static Model of the Universe: A Centennial Review [CL]

We present a historical review of Einstein’s 1917 paper ‘Cosmological Considerations in the General Theory of Relativity’ to mark the centenary of a key work that set the foundations of modern cosmology. We find that the paper followed as a natural next step after Einstein’s development of the general theory of relativity and that the work offers many insights into his thoughts on relativity, astronomy and cosmology. Our review includes a description of the observational and theoretical background to the paper; a paragraph-by-paragraph guided tour of the work; a discussion of Einstein’s views of issues such as the relativity of inertia, the curvature of space and the cosmological constant. Particular attention is paid to little-known aspects of the paper such as Einstein’s failure to test his model against observation, his failure to consider the stability of the model and a mathematical oversight in his interpretation of the role of the cosmological constant. We discuss the insights provided by Einstein’s reaction to alternate models of the universe proposed by Willem de Sitter, Alexander Friedman and Georges Lema\^itre. Finally, we consider the relevance of Einstein’s static model of the universe for today’s ’emergent’ cosmologies.

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C. ORaifeartaigh, M. OKeeffe, W. Nahm, et. al.
Thu, 26 Jan 17

Comments: Submitted to the European Physical Journal (H).70-page review, 4 figures

Evidence for a White-light Flare on 10 September 1886 [SSA]

We present evidence for the occurrence of a white-light flare on 10 September 1886. It represents the third of such rare events reported in the history of astronomy. The flare was mentioned by Valderrama (1886, L’Astronomie 5, 388). In this article we have used the original logbook of the observer, J. Valderrama y Aguilar, an amateur astronomer that lived in Madrid and Santa Cruz de Tenerife at that time.

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J. Vaquero, M. Vazquez and J. Almeida
Tue, 24 Jan 17

Comments: 11 pages, 3 figures, accepted for publication in Solar Physics

A maximum magnetic moment to angular momentum conjecture [CL]

Conjectures play a central role in theoretical physics, especially those that assert an upper bound to some dimensionless ratio of physical quantities. In this paper we introduce a new such conjecture bounding the ratio of the magnetic moment to angular momentum in nature. We also discuss the current status of some old bounds on dimensionless and dimensional quantities in arbitrary spatial dimension. Our new conjecture is that the dimensionless Schuster-Wilson-Blackett number, c{\mu}/JG^{(1/2)}, where {\mu} is the magnetic moment and J is the angular momentum, is bounded above by a number of order unity. We verify that such a bound holds for charged rotating black holes in those theories for which exact solutions are available, including the Einstein-Maxwell theory, Kaluza-Klein theory, the Kerr-Sen black hole, and the so-called STU family of charged rotating supergravity black holes. We also discuss the current status of the Maximum Tension Conjecture, the Dyson Luminosity Bound, and Thorne’s Hoop Conjecture.

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J. Barrow and G. Gibbons
Tue, 24 Jan 17

Comments: 24 pages, no figures

The role of cosmology in modern physics [CL]

Subject of this article is the relationship between modern cosmology and fundamental physics, in particular general relativity as a theory of gravity on one side, together with its unique application in cosmology, and the formation of structures and their statistics on the other. It summarises arguments for the formulation for a metric theory of gravity and the uniqueness of the construction of general relativity. It discusses symmetry arguments in the construction of Friedmann-Lema\^itre cosmologies as well as assumptions in relation to the presence of dark matter, when adopting general relativity as the gravitational theory. A large section is dedicated to $\Lambda$CDM as the standard model for structure formation and the arguments that led to its construction, and to the of role statistics and to the problem of scientific inference in cosmology as an empirical science. The article concludes with an outlook on current and future developments in cosmology.

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B. Schaefer
Wed, 18 Jan 17

Comments: 9 pages, invited contribution to the workshop “Why trust a theory?”, Dec.2015 in Munich

Records of sunspot and aurora activity during 581-959 CE in Chinese official histories in the periods of Suí, Táng, and the Five Dynasties and Ten Kingdoms [CL]

Recent studies of radioisotopes in tree rings or ice cores suggest that extreme space weather events occurred in the pre-telescope age. Observational records of naked-eye sunspots and low-latitude auroras in historical documents in pre-telescopic age can provide useful information on past solar activity. In this paper, we present the results of a comprehensive survey of records of sunspots and auroras in Chinese official histories from the 6th century to the 10th century, in the period of Su\’i, T\’ang, the Five Dynasties and Ten Kingdoms. These official histories contain records of continuous observations with well-formatted reports conducted under the policy of the government. A brief comparison of the frequency of observations of sunspots and auroras with the observations of radioisotopes as an indicator of solar activity during the corresponding periods is provided. Based on our data, we survey and compile the records of sunspots and auroras in historical documents from variouslocations and in several languages, and ultimately provide these as open data to the scientific community.

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H. Tamazawa, A. Kawamura, H. Hayakawa, et. al.
Tue, 13 Dec 16

Comments: 2016/12/10 accepted for publication in PASJ

Breaking symmetry, breaking ground [CL]

I give a short commentary on a seminal article by T W B Kibble in 1976, “Topology of cosmic domains and strings”.

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M. Hindmarsh
Tue, 13 Dec 16

Comments: Published in J. Phys. A as part of a series of Viewpoints on 50 influential papers, celebrating the 50th anniversary of the Journal of Physics series. The article is dedicated to Tom, who died while it was being prepared

Historical Auroras in the 990s: Evidence for Great Magnetic Storms [SSA]

Recently, a significant carbon-14 enhancement in the year 994 in tree rings has been found, suggesting an extremely large cosmic ray flux event during a short period. The origin of this particular cosmic ray event has not been confirmed, but one possibility is that it is of solar origin. Contemporary historical records of low latitude auroras can be used as supporting evidence for intense solar activity around that time. We investigated the previously reported as well as the new records found in contemporary observations from the 990s to determine potential auroras. Records of potential red auroras in the late 992 and early 993 were found around the world, i.e. in the Korean Peninsula, Germany, and the Island of Ireland, suggesting the occurrence of an intense geomagnetic storm driven by solar activity.

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H. Hayakawa, H. Tamazawa, Y. Uchiyama, et. al.
Tue, 6 Dec 16

Comments: 2016/12/01 accepted for publication in Solar Physics. Due to the matter of license, we cannot show some figures on the preprint version. Please see the published version in Solar Physics for the figures

Earliest Datable Records of Aurora-like Phenomena in the Astronomical Diaries from Babylonia [SSA]

The Astronomical Diaries from Babylonia (ADB) are an excellent source of information of natural phenomena, including astronomical ones, in pre-Christ era because it contains the record of highly continuous and systematic observations. In this article we present results of a survey of aurora-like phenomena in ADB, spanning from BCE 652 to BCE 61. We have found 9 records of aurora-like phenomena. Philological and scientific examinations suggest 5 of them can be considered as likely candidate for aurora observations. They provide unique information about the solar and aurora activities in the first millennium BCE.

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H. Hayakawa, Y. Mitsuma, Y. Ebihara, et. al.
Thu, 17 Nov 16

Comments: 2016/11/16 Accepted publication in Earth, Planets and Space

The earliest drawings of datable auroras and a two-tail comet from the Syriac Chronicle of Zūqnīn [CL]

People have probably been watching the sky since the beginning of human history. Observers in pre-telescopic ages recorded anomalous events and these astronomical records in the historical documents provide uniquely valuable information for modern scientists. Records with drawings are particularly useful, as the verbal expressions recorded by pre-telescopic observers, who did not know the physical nature of the phenomena, are often ambiguous. However, drawings for specific datable events in the historical documents are much fewer than the verbal records. Therefore, in this paper, we show the possible earliest drawings of datable auroras and a two-tail comet in a manuscript of the Chronicle of Z\=uqn\=in, a Syriac chronicle up to 775/776 CE to interpret their nature. They provide not only the historical facts in the realm around Amida but also information about low-latitude aurora observations due to extreme space weather events and the existence of sun-grazing comets.

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H. Hayakawa, Y. Mitsuma, Y. Fujiwara, et. al.
Wed, 2 Nov 16

Comments: 2016/10/26 accepted for publication in PASJ. Due to the matter of license, we cannot show some figures on the preprint version. Please see the published version in PASJ for the figures

The contrivance of Neptune [EPA]

Celebrating 170th anniversary of the discovery of Neptune, I review the story of the discovery that startled the world. The story is an interplay of scientific triumph and human weakness and an example of how science works in a socio-political context.

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D. Krajnovic
Fri, 21 Oct 16

Comments: A somewhat expanded version of the article published in A&G (October 2016). It differs in two additional text boxes pertaining to the Titius-Bode rule and the naming of the planet, and a correction to the table with pre-discovery sightings of Neptune. 17 pages, two figures and six explanatory boxes. Numeration of figures, tables and boxes is different from the published version

A Brief History of Gravitational Waves [CL]

This review describes the discovery of gravitational waves. We recount the journey of predicting and finding those waves, since its beginning in the early twentieth century, their prediction by Einstein in 1916, theoretical and experimental blunders, efforts towards their detection, and finally the subsequent successful discovery.

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J. Cervantes-Cota, S. Galindo-Uribarri and G. Smoot
Fri, 30 Sep 16

Comments: 30 pages

East Asian Observations of Low Latitude Aurora during the Carrington Magnetic Storm [SSA]

The magnetic storm around 1859 September 2, caused by so-called Carrington flare, was the most intense in the history of modern scientific observations, and hence is considered to be the benchmark event for space weather. The magnetic storm caused worldwide observations of auroras even at very low latitudes such as Hawaii, Panama, or Santiago, and the available magnetic field measurement at Bombay, India, showed two peaks: the main was the Carrington event which occurred in day time in East Asia, and a second storm after the Carrington event which occurred at night in East Asia. In this paper, we present a result from surveys of aurora records in East Asia, which provides new information of the aurora activity of this important event. We found some new East Asian records of low latitude aurora observations caused by the storm which occurred after the Carrington event. The size of the aurora belt of the second peak of the Carrington magnetic storm was even wider than usual low-latitude aurora events.

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H. Hayakawa, K. Iwahashi, H. Tamazawa, et. al.
Tue, 30 Aug 16

Comments: 2016/08/26 accepted for publication in PASJ. Due to the matter of license, we cannot show some figures on the preprint version. Please see the published version in PASJ for the figures

Life and space dimensionality: A brief review of old and new entangled arguments [CL]

A general sketch on how the problem of space dimensionality depends on anthropic arguments is presented. Several examples of how life has been used to constraint space dimensionality (and vice-versa) are reviewed. In particular, the influences of three-dimensionality in the solar system stability and the origin of life on Earth are discussed. New constraints on space dimensionality and on its invariance in very large spatial and temporal scales are also stressed.

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F. Caruso
Mon, 22 Aug 2016

Comments: 13 pages

How supernovae became the basis of observational cosmology [SSA]

This paper is dedicated to the discovery of one of the most important relationships in supernova cosmology – the relation between the peak luminosity of Type Ia supernovae and their luminosity decline rate after maximum light. The history of this relationship is quite long and interesting. The relationship was independently discovered by the American statistician and astronomer Bert Woodard Rust and the Soviet astronomer Yury Pavlovich Pskovskii in the 1970s. Using a limited sample of Type I supernovae they were able to show that the brighter the supernova is, the slower its luminosity declines after maximum. Only with the appearance of CCD cameras could Mark Phillips re-inspect this relationship on a new level of accuracy using a better sample of supernovae. His investigations confirmed the idea proposed earlier by Rust and Pskovskii.

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M. Pruzhinskaya and S. Lisakov
Tue, 16 Aug 16

Comments: 13 pages, 10 figures

Aurora Candidates from the Chronicle of Qīng Dynasty in Several Degrees of Relevance [SSA]

We present the result of the survey of sunspots and auroras in ${\it Q\bar{\imath}ngsh\check{\imath}ga\check{o}}$, the draft chronicle of ${\it Q\bar{\imath}ng}$ dynasty, for the period of 1559-1912 CE, as a sequel of the series of works surveying historical sunspot and aurora records, and providing online data to the scientific community regarding the attained results. In total of this ${\it Q\bar{\imath}ngsh\check{\imath}ga\check{o}}$ survey, we found 111 records of night-sky luminous events with the keywords such as vapor (${\it q\grave{\imath}}$), cloud (${\it y\acute{u}n}$), and light (${\it gu\bar{a}ng}$), which may indicate auroras as well as some other phenomena. Similarly keyword survey for sunspots were done, but no sunspot record was found. In comparison with the aurora records in the western world, we found 14 of the 111 records have a corresponding record of simultaneous observation in the western world and hence are very likely to be aurora. In order to investigate the likeliness of the rest of the record being aurora, we calculated the lunar age and the phase of a solar cycle for each record. After these calculations, notable fraction of these records clustered near the full moon were found statistically doubtful in considerations with atmospheric optics, meanwhile a few records near the new moon could be more likely interpreted as auroras including three records during the Maunder minimum.

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A. Kawamura, H. Hayakawa, H. Tamazawa, et. al.
Wed, 10 Aug 16

Comments: 34 pages, 5 figures, 2 tables, accepted for publication in PASJ

Lessons from Mayan Astronomy [CL]

The Mayan culture collected exquisite astronomical data for over a millennium. However, it failed to come up with the breakthrough ideas of modern astronomy because the data was analyzed within a mythological culture of astrology that rested upon false but mathematically sophisticated theories about the Universe. Have we learned the necessary lessons to prevent our current scientific culture from resembling Mayan Astronomy? Clearly, data collection by itself is not a guarantee for good science as commonly assumed by funding agencies. A vibrant scientific culture should cultivate multiple approaches to analyzing existing data and to collecting new data.

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A. Loeb
Mon, 8 Aug 16

Comments: 4 pages, 1 figure, to be published

Lo Gnomone Clementino Astronomia Meridiana in Basilica [IMA]

The Clementine Gnomon realized in 1702 by the astronomer Francesco Bianchini (1661-1729) upon the will of Pope Clement XI (1700-1721) in the Basilica of Santa Maria degli Angeli in Rome is fully reviewed about its scientific functions.

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C. Sigismondi
Mon, 25 Jul 16

Comments: 78 pages, with color images and photo. Text in Italian

Bayesian isochrone fitting and stellar ages [GA]

Stellar evolution theory has been extraordinarily successful at explaining the different phases under which stars form, evolve and die. While the strongest constraints have traditionally come from binary stars, the advent of asteroseismology is bringing unique measures in well-characterised stars. For stellar populations in general, however, only photometric measures are usually available, and the comparison with the predictions of stellar evolution theory have mostly been qualitative. For instance, the geometrical shapes of isochrones have been used to infer ages of coeval populations, but without any proper statistical basis. In this chapter we provide a pedagogical review on a Bayesian formalism to make quantitative inferences on the properties of single, binary and small ensembles of stars, including unresolved populations. As an example, we show how stellar evolution theory can be used in a rigorous way as a prior information to measure the ages of stars between the ZAMS and the Helium flash, and their uncertainties, using photometric data only.

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D. Valls-Gabaud
Tue, 12 Jul 16

Comments: 43 pages, Proceedings of the Evry Schatzman School of Stellar Astrophysics “The ages of stars”, EAS Publications Series, Volume 65

Interpretation of the historic Yemeni reports of supernova SN 1006: early discovery in mid-April 1006 ? [CL]

The recently published Yemeni observing report about SN 1006 from al-Yamani clearly gives AD 1006 Apr $17 \pm 2$ (mid-Rajab 396h) as first observation date. Since this is about 1.5 weeks earlier than the otherwise earliest reports (Apr 28 or 30) as discussed so far, we were motivated to investigate an early sighting in more depth. We searched for additional evidences from other areas like East Asia and Europe. We found that the date given by al-Yamani is fully consistent with other evidence, including: (a) SN 1006 “rose several times half an hour after sunset” (al-Yamani), which is correct for the location of Sana in Yemen for the time around Apr 17, but it would not be correct for late Apr or early May; (b) the date (3rd year, 3rd lunar month, 28th day wuzi, Ichidai Yoki) for an observation of a guest star in Japan is inconsistent (there is no day wuzi in that lunar month), but may be dated to Apr 16 by reading wuwu date rather than a wuzi date; (c) there is observational evidence that SN 1006 was observed in East Asia early or mid April; for the second half of April, a bad weather (early monsoon) period is not unlikely — there is a lack of night reports; (d) the observer in St. Gallen reported to have seen SN 1006 “for three months”, which must have ended at the very latest on AD 1006 Jul 10, given his northern location, so that his observations probably started in April. We conclude that the correctly reported details give quite high confidence in the fully self-consistent report of al-Yamani, so that the early discovery date should be considered seriously.

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R. Neuhaeuser, D. Neuhaeuser, W. Rada, et. al.
Tue, 12 Jul 16

Comments: 11 pages, 2 figures, 1 table (in press) in Astronomical Notes 2016

Dawes Review 5: Australian Aboriginal Astronomy and Navigation [IMA]

The traditional cultures of Aboriginal Australians include a significant astronomical component, perpetuated through oral tradition, ceremony, and art. This astronomical knowledge includes a deep understanding of the motion of objects in the sky, which was used for practical purposes such as constructing calendars and for navigation. There is also evidence that traditional Aboriginal Australians made careful records and measurements of cyclical phenomena, recorded unexpected phenomena such as eclipses and meteorite impacts, and could determine the cardinal points to an accuracy of a few degrees. Putative explanations of celestial phenomena appear throughout the oral record, suggesting traditional Aborig- inal Australians sought to understand the natural world around them, in the same way as modern scientists, but within their own cultural context. There is also a growing body of evidence for sophisticated navigational skills, including the use of astronomically based songlines. Songlines are effectively oral maps of the landscape, and are an efficient way of transmitting oral navigational skills in cultures that do not have a written language. The study of Aboriginal astronomy has had an impact extending beyond mere academic curiosity, facilitating cross-cultural understanding, demonstrating the intimate links between science and culture, and helping students to engage with science.

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R. Norris
Mon, 11 Jul 16

Comments: Accepted by PASA

Scientific Realism and Primordial Cosmology [CL]

We discuss scientific realism from the perspective of modern cosmology, especially primordial cosmology: i.e. the cosmological investigation of the very early universe.
We first (Section 2) state our allegiance to scientific realism, and discuss what insights about it cosmology might yield, as against “just” supplying scientific claims that philosophers can then evaluate. In particular, we discuss: the idea of laws of cosmology, and limitations on ascertaining the global structure of spacetime. Then we review some of what is now known about the early universe (Section 3): meaning, roughly, from a thousandth of a second after the Big Bang onwards(!).
The rest of the paper takes up two issues about primordial cosmology, i.e. the very early universe, where “very early” means, roughly, much earlier (logarithmically) than one second after the Big Bang: say, less than $10^{-11}$ seconds. Both issues illustrate that familiar philosophical threat to scientific realism, the under-determination of theory by data—on a cosmic scale.
The first issue (Section 4) concerns the difficulty of observationally probing the very early universe. More specifically, the difficulty is to ascertain details of the putative inflationary epoch. The second issue (Section 5) concerns difficulties about confirming a cosmological theory that postulates a multiverse, i.e. a set of domains (universes) each of whose inhabitants (if any) cannot directly observe, or otherwise causally interact with, other domains. This again concerns inflation, since many inflationary models postulate a multiverse.
For all these issues, it will be clear that much remains unsettled, as regards both physics and philosophy. But we will maintain that these remaining controversies do not threaten scientific realism.

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F. Azhar and J. Butterfield
Tue, 14 Jun 16

Comments: 52 pages. An abridged version will appear in “The Routledge Handbook of Scientific Realism”, ed. Juha Saatsi

Monitoring the Solar Radius from the Royal Observatory of the Spanish Navy during the Last Quarter-Millennium [SSA]

The solar diameter has been monitored at the Royal Observatory of the Spanish Navy (today the Real Instituto y Observatorio de la Armada: ROA) almost continuously since its creation in 1753 (i.e. during the last quarter of a millennium). After a painstaking effort to collect data in the historical archive of this institution, we present here the data of the solar semidiameter from 1773 to 2006, making up an extensive new database for solar-radius measurements can be considered. We have calculated the solar semidiameter from the transit times registered by the observers (except values of the solar radius from the modern Danjon astrolabe, which were published by ROA). These data were analysed to reveal any significant long-term trends, but no such trends were found. Therefore, the data sample confirms the constancy of the solar diameter during the last quarter of a millennium (approximately) within instrumental and methodological limits. Moreover, no relationship between solar radius and the new sunspot-number index has been found from measurements of the ROA. Finally, the mean value for solar semidiameter (with one standard deviation) calculated from the observations made in the ROA (1773-2006), after applying corrections by refraction and diffraction, is equal to 958.87″ \pm 1.77″

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J. Vaquero, M. Gallego, J. Ruiz-Lorenzo, et. al.
Tue, 14 Jun 16

Comments: 26 pages, 7 figures, to be published in Solar Physics

History of "Anomalous" Atmospheric Neutrino Events: A First Person Account [CL]

The modern picture of the neutrino as a multiple mass highly mixed neutral particle has emerged over 40 years of study. Best known of the issues leading to this picture was the apparent loss of neutrinos coming from the sun. This article describes another piece of evidence that supports the picture; the substantial reduction of high energy muon type neutrinos observed in nature. For much of the 40 year period, before the modern picture emerged this observation was known as the “atmospheric neutrino anomaly”, since as will be seen, these neutrinos originate in the Earth’s atmosphere.
This paper describes the discovery of the atmospheric neutrino anomaly. We explore the scientific context and motivations in the late 1970’s from which this work emerged. The gradual awareness that the observations of atmospheric neutrinos were not as expected took place in the 1983-1986 period.

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J. LoSecco
Fri, 3 Jun 16

Comments: 46 pages, 24 figures. To be published in Physics in Perspective

The infinite turn and speculative explanations in cosmology [CL]

Infinity, in various guises, has been invoked recently in order to `explain’ a number of important questions regarding observable phenomena in science, and in particular in cosmology. Such explanations are by their nature speculative. Here we introduce the notions of relative infinity, closure, and economy of explanation and ask: to what extent explanations involving relative or real constructed infinities can be treated as reasonable?

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R. Tavakol and F. Gironi
Mon, 25 Apr 16

Comments: N/A

Sunspot numbers based on historic records in the 1610s – early telescopic observations by Simon Marius and others [SSA]

Hoyt & Schatten (1998) claim that Simon Marius would have observed the sun from 1617 Jun 7 to 1618 Dec 31 (Gregorian calendar) all days, except three short gaps in 1618, but would never have detected a sunspot — based on a quotation from Marius in Wolf (1857), but misinterpreted by Hoyt & Schatten. Marius himself specified in early 1619 that “for one and a half year … rather few or more often no spots could be detected … which was never observed before” (Marius 1619). The generic statement by Marius can be interpreted such that the active day fraction was below 0.5 (but not zero) from fall 1617 to spring 1619 and that it was 1 before fall 1617 (since August 1611). Hoyt & Schatten cite Zinner (1952), who referred to Zinner (1942), where observing dates by Marius since 1611 are given, but which were not used by Hoyt & Schatten. We present all relevant texts from Marius where he clearly stated that he observed many spots in different form on and since 1611 Aug 3 (Julian) = Aug 13 (Greg.) (on the first day together with Ahasverus Schmidnerus), 14 spots on 1612 May 30 (Julian) = Jun 9 (Greg.), which is consistent with drawings by Galilei and Jungius for that day, the latter is shown here for the first time, at least one spot on 1611 Oct 3 and/or 11 (Julian), i.e. Oct 13 and/or 21 (Greg.), when he changed his sunspot observing technique, he also mentioned that he has drawn sunspots for 1611 Nov 17 (Julian) = Nov 27 (Greg.), in addition to those clearly datable detections, there is evidence in the texts for regular observations. … Sunspots records by Malapert from 1618 to 1621 show that the last low-latitude spot was seen in Dec 1620, while the first high-latitude spots were noticed in June and Oct 1620, so that the Schwabe cycle turnover (minimum) took place around that time, …

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R. Neuhaeuser and D. Neuhaeuser
Thu, 14 Apr 16

Comments: 40 pages with 6 tables and 13 figures (paper in press), Astronomical Notes 2016

The orientation as a signature of cultural identity: The historic churches of Lanzarote [CL]

The orientation of Christian churches is a well-known distinctive feature of their architecture. There is a general tendency to align their apses in the solar range, favoring orientations close to the east (astronomical equinox), although the alignments in the opposite direction, namely, with the apse towards the west, are not unusual. The case of the churches built in northwest Africa before the arrival of Islam is paradigmatic in this regard, and may reflect earlier traditions. The Canary Islands is the western end of this North African cultural koine, so we thought it would be relevant to study a compact set of old churches in one of the islands of the archipelago, choosing to start our project with Lanzarote. We have measured the orientation of a total of 30 churches built prior to 1810, as well as a few buildings of later times, nearly a complete sample of all the island Christian sanctuaries. The analysis of this sample indicates that a definite orientation pattern was followed on the island but, unlike the standard one often found in most of the Christian world, this prototype is twofold. On the one hand, the representative orientation to the east (or west) is present. However, the sample has also a marked orientation towards the north-northeast, which is as far as we know a pattern exclusive of Lanzarote. We analyze the reasons for this rule and suggest that one possible explanation could be a rather prosaic one, namely, that sometimes earthly needs are more relevant than religious beliefs.

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A. Gangui, A. Garcia, M. Betancort, et. al.
Thu, 14 Apr 16

Comments: Article in Spanish, PDF document including 1 table and 11 figures. Tabona, Revista de Prehistoria y Arqueologia, 20, in press 2016. Published version available at this http URL

An Arabic report about supernova SN 1006 by Ibn Sina (Avicenna) [SSA]

We present here an Arabic report about supernova 1006 (SN 1006) written by the famous Arabic scholar Ibn Sina (Lat. Avicenna, AD 980-1037), which was not discussed in astronomical literature before. The short observational report about a new star is part of Ibn Sina’s book called al-Shifa’, a work about philosophy including physics, astronomy, and meteorology. We present the Arabic text and our English translation. After a detailed discussion of the dating of the observation, we show that the text specifies that the transient celestial object was stationary and/or tail-less (“a star among the stars”), that it “remained for close to three months getting fainter and fainter until it disappeared”, that it “threw out sparks”, i.e. it was scintillating and very bright, and that the color changed with time. The information content is consistent with the other Arabic and non-Arabic reports about SN 1006. Hence, it is quite clear that Ibn Sina refers to SN 1006 in his report, given as an example for transient celestial objects in a discussion of Aristotle’s “Meteorology”. Given the wording and the description, e.g. for the color evolution, this report is independent from other reports known so far.

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R. Neuhaeuser, C. Ehrig-Eggert and P. Kunitzsch
Thu, 14 Apr 16

Comments: 7 pages with 1 figure, paper in press, Astronomical Notes 2016

Archaeoastronomy and the orientation of old churches [CL]

Cultural astronomy is an interdisciplinary area of research that studies how perceptions and concepts related to the sky are part of the worldview of a culture. One of its branches, archaeoastronomy, focuses on the material remains of past peoples and tries to investigate their practices and astronomical knowledge. In this context, the orientation of Christian churches is now considered a distinctive feature of their architecture that repeats patterns from early Christian times. There is a general tendency to align their altars in the solar range, with preference for orientations towards the east. Here we present recent data from our measurements of astronomical orientations of old churches located in two –geographically and culturally– very distant regions, and we discuss the results in the light of the historical and cultural knowledge surrounding these temples.

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A. Gangui
Mon, 4 Apr 16

Comments: Published version available at this http URL

Limits of time in cosmology [CL]

We provide a discussion of some main ideas in our project about the physical foundation of the time concept in cosmology. It is standard to point to the Planck scale (located at $\sim 10^{-43}$ seconds after a fictitious “Big Bang” point) as a limit for how far back we may extrapolate the standard cosmological model. In our work we have suggested that there are several other (physically motivated) interesting limits — located at least thirty orders of magnitude before the Planck time — where the physical basis of the cosmological model and its time concept is progressively weakened. Some of these limits are connected to phase transitions in the early universe which gradually undermine the notion of ‘standard clocks’ widely employed in cosmology. Such considerations lead to a ‘scale problem’ for time which becomes particularly acute above the electroweak phase transition (before $\sim 10^{-11}$ seconds). Other limits are due to problems of building up a cosmological reference frame, or even contemplating a sensible notion of proper time, if the early universe constituents become too quantum. This ‘quantum problem’ for time arises e.g. if a pure quantum phase is contemplated at the beginning of inflation at, say, $\sim 10^{-34}$ seconds.

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S. Rugh and H. Zinkernagel
Fri, 18 Mar 16

Comments: 20 pages, 1 figure. To appear in “The Philosophy of Cosmology”; edited by K. Chamcham, J. Silk, J. Barrow and S. Saunders. Cambridge University Press, 2016

The scientific impact of Einstein's visit to Argentina, in 1925 [CL]

The arrival of Albert Einstein in Argentina in 1925 had an impact, equally relevant, on the scientific community and on the general public. In this paper we discuss that visit from three different perspectives. Firstly, we consider the conditions that allowed for such visit to be possible. Then we focus on the institutional actors that facilitated it, as well as on the expertise and written references on topics related to relativity theory circulating at the time in the local community. In the last section we consider the implications of that visit for the local scientific environment.

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A. Gangui and E. Ortiz
Tue, 15 Mar 16

Comments: PDF document, 11 pages; Other related documents available at this http URL

"Unusual Rainbow and White Rainbow" A new auroral candidate in oriental historical sources [SSA]

Solar activity has been recorded as auroras or sunspots in various historical sources. These records are of much importance for investigating both long-term solar activities and extremely intense solar flares. In previous studies, they were recorded as “vapor,” “cloud,” or “light,” especially in oriental historical sources; however, the terminology was not discussed adequately and is still quite vague. In this paper, we suggest the possibility of “unusual rainbow” and “white rainbow” as candidates of historical auroras in oriental historical sources and examine if it is probable. This discovery will help us to make more comprehensive historical auroral catalogues and require us to add these terms to auroral candidates in oriental historical sources.

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H. Hayakawa, H. Isobe, A. Kawamura, et. al.
Wed, 9 Mar 16

Comments: Accepted by Publ. Astron. Soc. Japan

Spectra of conditionalization and typicality in the multiverse [CEA]

An approach to testing theories describing a multiverse, that has gained interest of late, involves comparing theory-generated probability distributions over observables with their experimentally measured values. It is likely that such distributions, were we indeed able to calculate them unambiguously, will assign low probabilities to any such experimental measurements. An alternative to thereby rejecting these theories, is to conditionalize the distributions involved by restricting attention to domains of the multiverse in which we might arise. In order to elicit a crisp prediction, however, one needs to make a further assumption about how typical we are of the chosen domains. In this paper, we investigate interactions between the spectra of available assumptions regarding both conditionalization and typicality, and draw out the effects of these interactions in a concrete setting; namely, on predictions of the total number of species that contribute significantly to dark matter. In particular, for each conditionalization scheme studied, we analyze how correlations between densities of different dark matter species affect the prediction, and explicate the effects of assumptions regarding typicality. We find that the effects of correlations can depend on the conditionalization scheme, and that in each case atypicality can significantly change the prediction. In doing so, we demonstrate the existence of overlaps in the predictions of different “frameworks” consisting of conjunctions of theory, conditionalization scheme and typicality assumption. This conclusion highlights the acute challenges involved in using such tests to identify a preferred framework that aims to describe our observational situation in a multiverse.

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F. Azhar
Mon, 25 Jan 16

Comments: 14 pages, 3 figures. Accepted for publication in Physical Review D

Kardashev's Classification at 50+: A Fine Vehicle with Room for Improvement [EPA]

We review the history and status of the famous classification of extraterrestrial civilizations given by the great Russian astrophysicist Nikolai Semenovich Kardashev, roughly half a century after it has been proposed. While Kardashev’s classification (or Kardashev’s scale) has often been seen as oversimplified, and multiple improvements, refinements, and alternatives to it have been suggested, it is still one of the major tools for serious theoretical investigation of SETI issues. During these 50+ years, several attempts at modifying or reforming the classification have been made; we review some of them here, together with presenting some of the scenarios which present difficulties to the standard version. Recent results in both theoretical and observational SETI studies, especially the G-hat infrared survey (2014-2015), have persuasively shown that the emphasis on detectability inherent in Kardashev’s classification obtains new significance and freshness. Several new movements and conceptual frameworks, such as the Dysonian SETI, tally extremely well with these developments. So, the apparent simplicity of the classification is highly deceptive: Kardashev’s work offers a wealth of still insufficiently studied methodological and epistemological ramifications and it remains, in both letter and spirit, perhaps the worthiest legacy of the SETI “founding fathers”.

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M. Cirkovic
Thu, 21 Jan 16

Comments: 15 pages, 2 figures, 2 tables

Transition of the Sunspot Number from Zurich to Brussels in 1980: A Personal Perspective [CL]

The Swiss Federal Observatory, which had been founded in 1863 by Rudolf Wolf, was dissolved in connection with the retirement of Max Waldmeier in 1979. The determination of the Zurich sunpot number, which had been a cornerstone activity of the observatory, was then discontinued by ETH Zurich. A smooth transition of the responsibility for the sunspot number from Zurich to Brussels could however be achieved in 1980, through which it was possible to avoid a discontinuity in this important time series. Here we describe the circumstances that led to the termination in Zurich, how Brussels was chosen for the succession, and how the transfer was accomplished.

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J. Stenflo
Tue, 22 Dec 15

Comments: N/A

Tribute to an astronomer: the work of Max Ernst on Wilhelm Tempel [CL]

In 1964-1974, the German artist Max Ernst created, with the help of two friends, a series of works (books, movie, paintings) related to the astronomer Wilhelm Tempel. Mixing actual texts by Tempel and artistic features, this series pays homage to the astronomer by recalling his life and discoveries. Moreover, the core of the project, the book Maximiliana or the Illegal Practice of Astronomy, actually depicts the way science works, making this artwork a most original tribute to a scientist.

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Y. Naze
Fri, 18 Dec 15

Comments: 18 pages, accepted by JHA

The Baltic Meetings 1957 to 1967 [CL]

The Baltic meetings of astronomers from Northern Germany and Scandinavia began in 1957 and gathered up to 70 participants. Reports of the presentations are available from all meetings, providing an overview of the interests of astronomers in this part of the world 50 years ago. Most interesting to see for a young astronomer in our days, I think, is that a large part of the time was about astrometry. This focus on astrometry was the basis for the scientific knowhow which made the idea of space astrometry realistic, resulting in the approval by ESA of the first astrometry satellite Hipparcos in 1980 which brought a revolution of high-precision astrometry of positions, motions and distances of stars. The correspondence with ten observatories shows that only one of them has any archive of letters at all from the 1950s, that is in Copenhagen where about 7000 letters on scientific and administrative matters are extant.

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E. Hog
Tue, 8 Dec 15

Comments: 11 pages, 3 figures

Young astronomer in Denmark 1946 to 1958 [CL]

This is a personal account of how I became an astronomer. Fascinated by the stars and planets in the dark sky over Lolland, an island 100 km south of Copenhagen, the interest in astronomy was growing. Encouraged by my teachers, I polished mirrors and built telescopes with generous help from the local blacksmith and I observed light curves of variable stars. Studies at the Copenhagen University from 1950 gradually led me deeper into astronomy, especially astrometry (the astronomy of positions), guided by professor Bengt Str\”omgren and my mentor dr. phil. Peter Naur. I was lucky to take part in the buildup of the new observatory at Brorfelde during the first difficult years and the ideas I gathered there have contributed to the two astrometry satellites Hipparcos and Gaia launched by the European Space Agency (ESA) in respectively 1989 and 2013.

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E. Hog
Tue, 8 Dec 15

Comments: 30 pages, 9 figures

The Fourth Microlensing Planet Revisited [CL]

The fourth microlensing planet, otherwise known as OGLE-2005-BLG-169Lb, was discovered by a collaboration of US, NZ, Polish and UK astronomers in 2005-2006. Recently the results were confirmed by the Hubble Space Telescope and by the Keck Observatory. OGLE-2005-BLG-169Lb is the first microlensing planet to receive such confirmation. Its discovery and confirmation are described here in an historical context.

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P. Yock
Mon, 7 Dec 15

Comments: 9 pages, 8 figures

Early Telescopes and Ancient Scientific Instruments in the Paintings of Jan Brueghel the Elder [IMA]

Ancient instruments of high interest for research on the origin and diffusion of early scientific devices in the late XVI – early XVII centuries are reproduced in three paintings by Jan Brueghel the Elder. We investigated the nature and the origin of these instruments, in particular the spyglass depicted in a painting dated 1609-1612 that represents the most ancient reproduction of an early spyglass, and the two sophisticated spyglasses with draw tubes that are reproduced in two paintings, dated 1617-1618. We suggest that these two instruments may represent early examples of keplerian telescopes. Concerning the other scientific instruments, namely an astrolabe, an armillary sphere, a nocturnal, a proportional compass, surveying instruments, a Mordente’s compass, a theodolite, etc., we point out that most of them may be associated with Michiel Coignet, cosmographer and instrument maker at the Court of the Archduke Albert VII of Hapsburg in Brussels.

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P. Selvelli and P. Molaro
Mon, 7 Dec 15

Comments: Published in Astronomy and its instruments before and after Galileo, Edited by Luisa Pigatto and Valeria Zanini 2009, p193-208

General Relativity in Post Independence India [CL]

The most outstanding contribution to general relativity in this era came in 1953 (published in 1955 \cite{akr}) in the form of the Raychaudhri equation. It is in 1960s that the observations began to confront the eupherial theory and thus began exploration of GR as a legitimate physical theory in right earnest. The remarkable discoveries of cosmic microwave background radiation, quasars, rotating Kerr black hole and the powerful singularity theorems heralded a new canvas of relativistic astrophysics and cosmology. I would attempt to give a brief account of Indian participation in these exciting times.

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N. Dadhich
Fri, 4 Dec 15

Comments: 16 pages, latex

A brief history of the multiverse [CL]

The theory of the inflationary multiverse changes the way we think about our place in the world. According to its most popular version, our world may consist of infinitely many exponentially large parts, exhibiting different sets of low-energy laws of physics. Since these parts are extremely large, the interior of each of them behaves as if it were a separate universe, practically unaffected by the rest of the world. This picture, combined with the theory of eternal inflation and anthropic considerations, may help to solve many difficult problems of modern physics, including the cosmological constant problem. In this article I will briefly describe this theory and provide links to the some hard to find papers written during the first few years of the development of the inflationary multiverse scenario.

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A. Linde
Fri, 4 Dec 15

Comments: 12 pages, 1 figure

Atomic beings and the discovery of gravity [CEA]

We aim to bring a new perspective about some aspects of the current research in Cosmology. We start with a brief introduction about the main developments of the field in the last century; then we introduce an analogy that shall elucidate the main difficulties that observational sciences involve, which might be part of the issue related to some of the contemporary cosmological problems. The analogy investigates how microscopic beings could ever discover and understand gravitational phenomena.

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G. Conto and G. Franzmann
Wed, 18 Nov 15

Comments: 16 pages, 2 figures

Astronomy and Astrophysics in the Philosophy of Science [CL]

This article looks at philosophical aspects and questions that modern astrophysical research gives rise to. Other than cosmology, astrophysics particularly deals with understanding phenomena and processes operating at “intermediate” cosmic scales, which has rarely aroused philosophical interest so far. Being confronted with the attribution of antirealism by Ian Hacking because of its observational nature, astrophysics is equipped with a characteristic methodology that can cope with the missing possibility of direct interaction with most objects of research. In its attempt to understand the causal history of singular phenomena it resembles the historical sciences, while the search for general causal relations with respect to classes of processes or objects can rely on the “cosmic laboratory”: the multitude of different phenomena and environments, naturally provided by the universe. Furthermore, the epistemology of astrophysics is strongly based on the use of models and simulations and a complex treatment of large amounts of data.

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S. Anderl
Tue, 13 Oct 15

Comments: 14 pages, This is a draft of a chapter “Astronomy and Astrophysics” that has been accepted for publication by Oxford University Press in the forthcoming book “The Oxford Handbook of Philosophy of Science” edited by Paul Humphreys due for publication in May 2016

Presumable European aurorae in the mid AD 770s were halo displays [CL]

The interpretation of the strong 14-C variation around AD 775 as one (or several) solar super-flare(s) by, e.g., Usoskin et al. (2013) is based on alleged aurora sightings in the mid AD 770s in Europe: A “red cross/crucifix” in AD 773/4/6 from the Anglo-Saxon Chronicle, “inflamed shields” in AD 776 (both listed in the aurora catalogue of Link 1962), and “riders on white horses” in AD 773 (newly proposed as aurora in Usoskin et al. 2013), the two latter from the Royal Frankish Annals. We discuss the reports about these three sightings in detail here. We can show that all three were halo displays: The “red cross” or “crucifix” is formed by the horizontal arc and a vertical pillar of light (either with the Sun during sunset or with the moon after sunset); the “inflamed shields” and the “riders on white horses” were both two mock suns, especially the latter narrated in form of a Christian adaptation of the antique dioscuri motive. While the latter event took place early in AD 774 (dated AD 773 in Usoskin et al. 2013), the two other sightings have to be dated AD 776, i.e. anyway too late for being in connection with a 14-C rise that started before AD 775. We also sketch the ideological background of those sightings and there were many similar reports throughout that time. In addition, we present a small drawing of a lunar halo display with horizontal arc and vertical pillar forming a cross for shortly later, namely AD 806 June 4, the night of full moon, also from the Anglo-Saxon Chronicle; we also show historic drawings of solar and lunar halo crosses from G. Kirch and Helevius and a modern photograph.

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D. Neuhaeuser and R. Neuhaeuser
Tue, 1 Sep 15

Comments: 17 pages with 6 figures Astronomical Notes in press

The Grand Aurorae Borealis Seen in Colombia in 1859 [CL]

On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama’s 9$^\circ$ N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia, allowing the identification of a narrative from Monter\’ia, Colombia (8$^\circ$ 45′ N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling glares, and the appearance of an immense S-like shape in the sky. The very low latitude of the geomagnetic north pole in 1859, the lowest value in over half a millennia, is proposed to have allowed the observations of auroral events at locations closer to the equator, and supports the historical description found in Colombia. The finding of such chronicle represents one of the most complete descriptions of low-latitude sightings of aurorae caused by the Carrington Event.

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F. Cardenas, S. Sanchez and S. Dominguez
Thu, 27 Aug 15

Comments: 26 pages, 10 figures. Accepted for publication in Advances in Space Research

Supernova SN 1006 in two historic Yemeni reports [CL]

We present two Arabic texts of historic observations of supernova SN 1006 from Yemen as reported by al-Yamani and Ibn al-Dayba (14th to 16th century AD). An English translation of the report by the latter was given before (Stephenson & Green 2002), but the original Arabic text was not yet published. In addition, we present for the first time the earlier report, also from Yemen, namely by al-Yamani in its original Arabic and with our English translation. It is quite obvious that the report by Ibn al-Dayba is based on the report by al-Yamani (or a common source), but the earlier report by al-Yamani is more detailed and in better (Arabic) language. We discuss in detail the dating of these observations. The most striking difference to other reports about SN 1006 is the apparent early discovery in Yemen in the evening of 15th of Rajab of the year 396h (i.e. AD 1006 Apr 17 \pm 2 on the Julian calendar), as reported by both al-Yamani and Ibn al-Dayba. i.e. about 1.5 weeks earlier than the otherwise earliest known reports. We also briefly discuss other information from the Yemeni reports on brightness, light curve, duration of visibility, location, stationarity, and color.

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W. Rada and R. Neuhaeuser
Wed, 26 Aug 15

Comments: 9 pages with 3 figures