Serendipity: an Argument for Scientific Freedom?

The unpredictability of the development and results of a research program is often invoked in favor of a free, desinterested science that would be led mainly by scientific curiosity, in contrast with a use-inspired science led by definite practical expectations. This paper will challenge a crucial but underexamined assumption in this line of defense of scientific freedom, namely that a free science is the best system of science to generate unexpected results. We will propose conditions favoring the occurrence of unexpected facts in the course of a scientific investigation and then establish that use-inspired science actually scores better in this area

Learning from a simulated universe: the limits of realistic modeling in astrophysics and cosmology.

As noticed recently by Winsberg (2003), how computer models and simulations get their epistemic credentials remains in need of epistemological scrutiny. My aim in this paper is to contribute to fill this gap by discussing underappreciated features of simulations (such as “path-dependency” and plasticity) which, I’ll argue, affect their validation. The focus will be on composite modeling of complex real-world systems in astrophysics and cosmology. The analysis leads to a reassessment of the epistemic goals actually achieved by this kind of modeling: I’ll show in particular that its realistic ambition and the possibility of empirical confirmation pull in opposite directions

Regards philosophiques sur la question de la démarcation entre science et non-science aujourd’hui

Les enjeux de la question de la démarcation entre science et non-science se trouvent profondément renouvelés dans nos sociétés contemporaines qui placent les sciences et l’innovation technologique au cœur de leur développement. Quelles ressources offre aujourd’hui la philosophie des sciences pour penser cette démarcation et proposer des critères de démarcation opérationnels ? Sans souci d’exhaustivité, cet article présente quelques-unes des principales propositions philosophiques récentes en la matière, qui ont en commun de prendre acte à la fois de l’insuffisance des critères épistémologiques classiques proposés au XXe siècle et de l’abandon d’une vision unitaire des sciences qui allait de pair avec ces critères.The issues of the demarcation between science and non science are significantly renewed in our contemporary societies, which put science and technological innovation at the center of their development. Which resources are offered today by philosophy of science to think this demarcation and propose operational criteria of demarcation? This article presents some of the main recent relevant philosophical propositions, which acknowledge both the shortcomings of the traditional epistemological criteria proposed last century and the abandonment of unitary view of science that used to go hand in hand with these criteria

Natural kinds: a new synthesis

¿Qué es una clase natural? Esta pregunta filosófica, antigua pero perdurable, ha recibido recientemente nuevas respuestas enfrentadas (e.g., Chakravartty, 2007; Magnus, 2014; Khalidi, 2013; Slater, 2015; Ereshefsky and Reydon, 2015). En este artículo mostramos que los principales ingredientes para una explicación abarcadora y coherente de las clases naturales están de hecho disponibles, aunque a la espera de una articulación apropiada. Adoptando una perspectiva no reduccionista, naturalista y no conceptualista, elaboramos una nueva síntesis a partir de estos ingredientes. Nuestra propuesta es una teoría de las clases naturales que los define en términos puramente ontológicos, que distingue y relaciona claramente cuestiones ontológicas y epistemológicas -en concreto, dos tipos de descripción ontológica y dos formas de éxito explicativo para las clases naturales-, y que arroja luz sobre por qué las clases naturales desempeñan un papel epistémico tanto en la ciencia como en la vida cotidiana.; What is a natural kind? This old yet lasting philosophical question has recently received new competing answers (e.g., Chakravartty, 2007; Magnus, 2014; Khalidi, 2013; Slater, 2015; Ereshefsky and Reydon, 2015). We show that the main ingredients of an encompassing and coherent account of natural kinds are actually on the table, but in need of the right articulation. It is by adopting a non-reductionist, naturalistic and non-conceptualist approach that, in this paper, we elaborate a new synthesis of all these ingredients. Our resulting proposition is a multiple-compartment theory of natural kinds that defines them in purely ontological terms, clearly distinguishes and relates ontological and epistemological issues - more precisely, two grains of ontological descriptions and two grains of explanatory success of natural kinds -, and which sheds light on why natural kinds play an epistemic role both within science and in everyday life

Tendances de la recherche sur l'intégrité scientifique

Plus d’une trentaine d’années après la création des premières structures dédiées à sa promotion, l’intégrité scientifique s’est progressivement constituée en tant que thématique de recherche à part entière. Aujourd’hui, une communauté scientifique et académique est réunie autour de cet objet, comme en témoignent la publication d’un nombre croissant d’articles, la création de revues spécialisées ou encore l’organisation de conférences spécifiquement dédiées. Néanmoins, rares sont les travaux qui ont cherché à proposer une vue d’ensemble de la littérature académique relative à l’intégrité scientifique. C’est dans cette perspective que cet état de l’art s’inscrit et entend apporter une contribution. Avec la volonté de rendre compte des principales tendances de la recherche en la matière, nous avons principalement ciblé dans ce travail des articles, des commentaires ou encore quelques documents institutionnels qui ont cherché à approfondir la compréhension que l’on a de l’intégrité scientifique, à explorer les diverses façons de la promouvoir, à mieux cerner l’occurrence des manquements qui y sont liés, ou encore à proposer une lecture de ces questions sous un angle spécifique. Certaines des thématiques qui sont abordées dans cet état de l’art sont incontournables dans le paysage de la recherche et font l’objet d’une attention marquée depuis longtemps, à l’image de l’étude des manquements à l’intégrité scientifique. D’autres, à l’instar des études historiques de l’intégrité scientifique, représentent des pistes de recherche un peu moins explorées mais dont l’intérêt nous semble assez important pour appeler à davantage de développements

The Edge of the Milky Way Stellar Disk Revealed Using Clump Giant Stars as Distance Indicators

We use the clump giants of the disk as standard candles calibrated from Hipparcos parallaxes in order to map their distribution with two new near-IR surveys of the Galactic plane: UKIDSS-GPS and VVV. We explore different selection cuts of clump giants. We conclude that there is an edge of the stellar disk of the Milky Way at R=13.9+/-0.5kpc along various lines of sight across the galaxy. The effect of the warp is considered, taking fields at different longitudes and above and below the plane. We demonstrate that the edge of the stellar disk of the Milky Way can now be mapped in the near infrared in order to test different models, and to establish our own place within the galaxy

Probing the Galaxy's bars via the Hercules stream

It has been suggested that a resonance between a rotating bar and stars in the solar neighbourhood can produce the so called 'Hercules stream'. Recently, a second bar may have been identified in the Galactic centre, the so called 'long bar', which is longer and much flatter than the traditional Galactic bar, and has a similar mass. We looked at the dynamical effects of both bars, separately and together, on orbits of stars integrated backwards from local position and velocities, and a model of the Galactic potential which includes the bars directly. Both bars can produce Hercules like features, and allow us to measure the rotation rate of the bar(s). We measure a pattern speed, for both bars, of 1.87 +/- 0.02 times the local circular frequency. This is on par with previous measurements for the Galactic bar, although we do adopt a slightly different Solar motion. Finally, we identify a new kinematic feature in local velocity space, caused by the long bar, which is tempting to identify with the high velocity 'Arcturus' stream.Comment: 9 pages, 10 figures, Accepted to MNRAS, Corrected for errat

Calibrated and completeness-corrected optical stellar density maps of the Northern Galactic Plane

© The Author 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.Following on from the second release of calibrated photometry from IPHAS, the INT/WFC Photometric Hα Survey of the Northern Galactic Plane, we present incompleteness-corrected stellar density maps in the r and i photometric bands. These have been computed to a range of limiting magnitudes reaching to 20th magnitude in r and 19th in i (Vega system), and with different angular resolutions – the highest resolution available being 1 arcmin2. The maps obtained cover 94 per cent of the 1800 square degree IPHAS footprint, spanning the Galactic latitude range, −5◦ < b < +5◦, north of the celestial equator. The corrections for incompleteness, due to confusion and sensitivity loss at the faint limit, have been deduced by the method of artificial source injection. The presentation of this method is preceded by a discussion of other more approximate methods of determining completeness. Our method takes full account of position-dependent seeing and source ellipticity in the survey data base. The application of the star counts to testing reddened Galactic disc models is previewed by a comparison with predicted counts along three constant-longitude cuts at 30◦, 90◦ and 175◦: some overprediction of the most heavily reddened 30◦ counts is found, alongside good agreement at 90◦ and 175◦. KeyPeer reviewedFinal Published versio

The puzzle about the radial cut-off in galactic disks

The stellar disk in a spiral galaxy is believed to be truncated physically because the disk surface brightness is observed to fall faster than that for an exponential in the outer, faint regions. We review the literature associated with this phenomenon and find that a number of recent observations contradict the truncation picture. Hence we question the very existence of a physical outer cut-off in stellar disks. We show, in this paper, that the observed drop in the surface brightness profiles in fact corresponds to a negligible decrease in intensity, and that this minor change at the faint end appears to be exaggerated on a log-normal plot. Since minor deviations from a perfect exponential are common throughout the disk, we suggest that such a deviation at the faint end could easily give rise to the observed sharp drop.Comment: 4 pages, 3 .eps figures, Astron. & Astrophys Letters, In pres

Disentangling the Galaxy at low Galactic latitudes

We have used the field stars from the open cluster survey BOCCE, to study three low-latitude fields imaged with the Canada-France-Hawaii telescope (CFHT), with the aim of better understanding the Galactic structure in those directions. Due to the deep and accurate photometry in these fields, they provide a powerful discriminant among Galactic structure models. In the present paper we discuss if a canonical star count model, expressed in terms of thin and thick disc radial scales, thick disc normalization and reddening distribution, can explain the observed CMDs. Disc and thick disc are described with double exponentials, the spheroid is represented with a De Vaucouleurs density law. In order to assess the fit quality of a particular set of parameters, the colour distribution and luminosity function of synthetic photometry is compared to that of target stars selected from the blue sequence of the observed colour-magnitude diagrams. Through a Kolmogorov-Smirnov test we find that the classical decomposition halo-thin/thick disc is sufficient to reproduce the observations--no additional population is strictly necessary. In terms of solutions common to all three fields, we have found a thick disc scale length that is equal to (or slightly longer than) the thin disc scale.Comment: Accepted for publication on MNRA