Astrophysics is often cast as an observational science, devoid of traditional experiments, along with astronomy and cosmology. Yet, a thriving field of experimental research exists called laboratory astrophysics. How should we make sense of this apparent tension? I argue that approaching the epistemology of astrophysics by attending to the production of empirical data and the aims of the research better illuminates both the successes and challenges of empirical research in astrophysics than evaluating the epistemology of (...) class='Hi'>astrophysics according to the presence or absence of experiments. (shrink)

I explore how the notion of divine creation could be made understandable in a worldview dominated by empirical science. The crucial question concerns the empirical basis of belief in creation. Astronomical observations have changed our worldview in an exemplary manner. I show by an example from imaginative literature that human beings can perceive stars by means other than astronomical observation. This alternative mode may be described as “participatory perception,” in which a human experiences the world not by objectifying separation as (...) in science, but by personal involvement. I relate such perceptions to “embodied cognitive science,” a topical interdisciplinary field of research in philosophy, psychology, and neuroscience. Embodied cognitions initiate processes that can convey personal experiences of the stars. Such cognitions may involve religious apprehensions and give rise to sophisticated values. It is argued that the knowledge available through astrophysics and interpretation of the universe as divine creation represent two different ways of perceiving the same reality and should thus be seen as mutually complementary. (shrink)

Evidence for instances of astrophysical 'fine tuning' (or 'coincidences') is thought by some to lend support to the design argument (i.e. the argument that our universe has been designed by some deity). We assess some of the relevant empirical and conceptual issues. We argue that astrophysical fine tuning calls for some explanation, but this explanation need not appeal to the design argument. A clear and strict separation of the issue of anthropic fine tuning on one hand and any form of (...) Eddingtonian numerology and teleology on the other, may help clarify arguably the most significant issue in the philosophy of cosmology. (shrink)

Evidence for instances of astrophysical ‘fine tuning’ (or ‘coincidences’) is thought by some to lend support to the design argument (i.e. the argument that our universe has been designed by some deity). We assess some of the relevant empirical and conceptual issues. We argue that astrophysical fine tuning calls for some explanation, but this explanation need not appeal to the design argument. A clear and strict separation of the issue of anthropic fine tuning on one hand and any form of (...) Eddingtonian numerology and teleology on the other, may help clarify arguably the most significant issue in the philosophy of cosmology. (shrink)

This book fills that void and is a welcome addition on that count."--Ronald F. Webbink, University of Illinois, Urbana-Champaign.

This is an open access book. This book, the first edited collection of its kind, explores the recent emergence of philosophical research in astrophysics. It assembles a variety of original essays from scholars who are currently shaping this field, and it combines insightful overviews of the current state of play with novel, significant contributions. It therefore provides an ideal source for understanding the current debates in philosophy of astrophysics, and it offers new ideas for future cutting-edge research. The (...) selection of essays offered in this book addresses methodological and metaphysical questions that target a wide range of topics, including dark matter, black holes, astrophysical observations and modelling. The book serves as the first standard resource in philosophy of astrophysics for all scholars who work in the field and want to expand or deepen their knowledge, but it also provides an accessible guide for all those philosophers and scientists who are interested in getting a first, basic understanding of the main issues in philosophy of astrophysics. (shrink)

While written by a prominent and active scientist, this book is based on personal experience and biblical theology. It doesn't try to derive God s existence from science and it's critical of scientific inferences on the notion of God (Natural Theology). Cosmic fine-tuning and other coincidences are no proof of God, but are amazing, astounding and will never be fully explained. Amazement is the appropriate emotional perception of reality. The objective world is not a matter of course and may well (...) not exist at all; thus reality, at times, is experienced to be very special. Human life, the beauty of nature, the habitability of planet Earth can be considered undeserved gifts. In the light of these gifts, the universe is metaphorically interpreted and existentially believed as a divine Creation. Science cannot create such faith but can foster it. Is God necessary to explain the universe? Is the idea of a Creator excluded by modern science? Why continue speaking of a Creator and to believe (trust and hope) in His continuing creation when God cannot be demonstrated in scientific data? Arnold Benz, a renowned astrophysicist and Christian, insists that human perception reaches further than science and demonstrates this in various examples, personal, biblical, and literary.". (shrink)

The articles included in this Volume represent a broad and highly qualified view on the present state of general relativity, quantum gravity, and their cosmological and astrophysical implications. As such, it may serve as a valuable source of knowledge and inspiration for experts in these fields, as well as an advanced source of information for young researchers. The occasion to gather together so many leading experts in the field was to celebrate the centenary of Einstein's stay in Prague in 1911-1912. (...) It was in fact during his stay in Prague that Einstein started in earnest to develop his ideas about general relativity that fully developed in his paper in 1915. Approaching soon the centenary of his famous paper, this volume offers a precious overview of the path done by the scientific community in this intriguing and vibrant field in the last century, defining the challenges of the next 100 years. The content is divided into four broad parts: (i) Gravity and Prague, (ii) Classical General Relativity, (iii) Cosmology and Quantum Gravity, and (iv) Numerical Relativity and Relativistic Astrophysics. (shrink)

We use the Tolman–Oppenheimer–Volkoff equations for a Chaplygin type fluid to study, analytically and numerically, the global behavior of static solutions of spherically symmetric objects. Two possible regimes are especially investigated. The first one is the phantom regime in which the pressure module exceeds the energy density. In this case the equator is absent and all the solutions have the geometry of a truncated spheroid with the same kind of singularity. The second case is the normal regime for which we (...) determine all the solutions, excluding the de Sitter one, corresponding to a tri-dimensional spheroidal geometry. Beyond the equator, three possible cases are considered; the first case has a closed spheroid characterized by a Schwarzschild-kind singularity with an infinite blue-shift at the south pole, the second case configuration has a regular spheroid and the third case has configuration of a truncated spheroid having a scalar curvature singularity to a finite value of the radial distance. We also compare all the geometric configurations with ones obtained in the special case of Chaplygin gas. (shrink)

With the ever-growing quality of observational data in astronomy, the complexity of astrophysical models has been increasing in turn. This trend raises the question: Are there still reasons to prefer simpler models if the final goal is an actual model-target comparison? I argue for two aspects in which astrophysical research may favor models having reduced complexity: first, to address the problem of determining the values of adjustable parameters and, second, to pave the way for a validation of the model based (...) on the modeler’s understanding of the scope of the model and the critical processes on the target’s side. (shrink)

Astrophysics is a scientific field with a rich ontology of individual processes and general phenomena that occur in our universe. Despite its central role in our understanding of the physics of the universe, astrophysics has largely been ignored in the debate on scientific realism. As a notable exception, Hacking (Philos Sci 56(4):555–581, 1989) argues that the lack of experiments in astrophysics forces us to be anti-realist with respect to the entities which astrophysics claim inhabit the universe. (...) In this paper, I investigate the viability of astrophysical realism about black holes, given other formulations of entity realism, specifically Cartwright’s (How the Laws of Physics Lie. Oxford University Press, 1983), and Chakravartty’s (A Metaphysics for Scientific Realism: Knowing the Unobervable. Cambridge University Press, 2007) versions of entity realism. I argue that on these accounts of entity realism, you cannot be a realist with respect to black holes, and likewise, if you want to be a realist about black holes, you cannot be an entity realist of these particular strands. (shrink)

Aristotle usually has an extremely bad reputation as a physicist among scientists and historians of science. Central to this is the treatment of his version of the geocentric conception of the cosmos, according to which the earth is at the centre of the cosmos and does not move, and which was the dominant picture in antiquity and throughout the middle ages. Aristotle’s view is commonly regarded as a pernicious influence on the course of cosmology until the Renaissance, one which held (...) sway only because of Aristotle’s authority. The chapter argues that his integration of astronomy and physics—his pursuit, in a variety of works written over a long period, of the question: ‘what does the world have to be like, in terms of a unified physics, if current astronomical theory is right?’—embodies a degree of comprehensiveness, sophistication, and elegance simply unparalleled in the ancient world. It is also more robust—given the astronomy of Aristotle’s day—than is usually thought: the chapter considers a number of difficulties it faced, and outlines responses which Aristotle either did make or could have made. The only serious rival to Aristotle’s astrophysics before Kepler and Newton was the theory set out in Ptolemy’s Planetary Hypotheses, which attempts to integrate physics with his astronomy: the chapter argues that for all its subtlety, this theory fares very poorly as a piece of physics. It was not, therefore, simple deference to authority which led some Islamic and Renaissance scientists to prefer Aristotle’s theory even though they could not see how to square it with Ptolemaic astronomy. (shrink)

This chapter examines some of the philosophical literature on idealizations in science and the epistemic challenges idealizations potentially pose for astrophysical methodology, particularly its use of computer simulations. We begin by surveying philosophical literature on idealization connected to (1) kinds of idealizations deployed in science, (2) the aims of idealization in science, and (3) various strategies for de-idealization. Using collisional ring galaxy simulations as a case study, we examine how these three themes play out in the context of astrophysical computer (...) simulations. Ultimately, we argue that deploying deidealization strategies is central to bolstering epistemic confidence in simulations in astrophysics. We conclude with some remarks on the role of idealization in the context of astrophysical computer simulations more generally. (shrink)

This article discusses Xenophanes' “cloud astro-physics”. It analyses and explains all heavenly and meteorological phenomena in terms of clouds. It provides a view of this newer Xenophanes, who is now being recognized as an important philosopher-scientist in his own right and a crucial figure in the development of critical thought about human knowledge and its objects in the next generation of Presocratic thinkers. Xenophanes' account has been preserved in Aëtius, the doxographic compendium reconstructed by Hermann Diels late in the nineteenth (...) century mainly from two sources that show extensive parallelism: pseudo-Plutarch Placita Philosophorum or Epitome of Physical Opinions ; and Ioannes Stobaeus' Eclogae Physicae or Physical Extracts. In the Stobaeus version, which is also the one printed in the standard edition of the Pre-socratics. (shrink)

Astrophysics faces methodological challenges as a result of being a predominantly observation-based science without access to traditional experiments. In light of these challenges, astrophysicists frequently rely on computer simulations. Using collisional ring galaxies as a case study, I argue that computer simulations play three roles in reasoning in astrophysics: (1) hypothesis testing, (2) exploring possibility space, and (3) amplifying observations.

In the context of astrophysical modeling at the solar system scale, we investigate the modalities implied by taking into account different levels of detail at which phenomena can be considered. In particular, by framing the analysis in terms of the how-possibly/how-actually distinction, we address the debated question as to whether the degree of plausibility is tightly linked to the degree of detail. On the grounds of concrete examples, we argue that, also in the astrophysical context examined, this is not necessarily (...) the case. (shrink)

This article argues in favour of an inferential role for fictions in scientific modelling. The argument proceeds by means of a detailed case study, namely models of the internal structure of stars in stellar astrophysics. The main assumptions in such models are described, and it is argued that they are best understood as useful fictions. The role that conditionals play in these models is explained, and it is argued that fictional assumptions play an important role as either background or (...) antecedent conditions. I then expand on the argument for the compatibility of fictions and scientific realism. I argue that realism and antirealism plausibly offer correspondingly different accounts of the semantics of these fictional conditionals. (shrink)

We report the results of an exploratory study that examines the judgments of climate scientists, climate policy experts, astrophysicists, and non-experts (N = 3367) about the factors that contribute to the creation and persistence of disagreement within climate science and astrophysics and about how one should respond to expert disagreement. We found that, as compared to non-experts, climate experts believe that within climate science (i) there is less disagreement about climate change, (ii) methodological factors play less of a role (...) in generating disagreements, (iii) fewer personal or institutional biases influence climate research, and (iv) there is more agreement about which methods should be used to examine relevant phenomena we also observed that the uniquely American political context predicted experts’ judgments about some of these factors. We also found that, in regard to disagreements concerning cosmic ray physics, and commensurate with the greater inherent uncertainty and data lacunae in their field, astrophysicists working on cosmic rays were generally more willing to acknowledge expert disagreement, more open to the idea that a set of data can have multiple valid interpretations, and generally less quick to dismiss someone articulating a non-standard view as non-expert, than climate scientists were in regard to climate science. (shrink)

A brief, simple introduction to the theory of radiation and its application in astrophysics and a manual for researchers. The purpose of this book is twofold: to provide a brief, simple introduction to the theory of radiation and its applcation in astrophysics and to serve as a refernce manual for researchers. The first part of the book consists of a dicussion of the basic formulas and concepts that underlie the classical and quantum descriptions of radiation processes. The rest (...) of the book is concerned with applications. The spirit of the discussion is to present simple derivations that will provide some insight into the basic physics involved and then to state the exact results in a form useful for applications. The reader is referred to the original literature and to reviews for rigorous derivations. Contents Basic Formulas for Classical Radiation Processes * Basic Formulas for Quantum Radiation Processes * Cyclotron and Synchrotron Radiation * Electron Scattering * Bremsstrahlung and Collision Losses * Rediative Recombination * The Photoelectric Effect * and Emission and Absorption Lines. (shrink)

This dissertation examines the dynamical dark matter problem in twentieth century astrophysics from the point of view of History and Philosophy of Science. The dynamical dark matter problem describes the situation astronomers find themselves in with regard to the dynamics of large scale astrophysical systems such as galaxies and galaxy clusters: The observed motions are incompatible with the visible distribution matter given the accepted law of gravitation. This discrepancy has two classes of possible solutions: either there exists copious amounts (...) of some kind of matter that neither emits nor absorbs radiation , or the law of gravitation must be revised. ;Chapter 2 describes the physical and philosophical foundations of dynamical inferences---inferences from discrepancies between well-founded theoretical expectations and reliable observations to the characteristics of candidate solutions. Chapter 3 discusses the history of dark matter . Chapter 4 reviews the present evidence bearing on the dark matter problem. Chapter 5 evaluates the important candidate matter solutions in light of the available evidence. Chapter 6 evaluates two candidate gravitational solutions on evidential and methodological grounds, and addresses the problem of theory choice. I do not try to solve the dark matter problem, but to uncover and evaluate patterns of inference involved in evidential arguments for and against candidate solutions. ;I show that Newton's "Reasoning from Phenomena" is a good framework from which to understand what is going on in this field. I argue that "higher order" and especially non-dynamical evidence is the best hope for solving this problem in dynamics. This is so in part because of "the dark matter double bind": the very existence of the dark matter problem means that we cannot be sure of the overall matter distribution in astrophysical systems, and this in turn means that the observed motions by themselves cannot provide relative confirmation of any theory of gravitational interactions taking place at these scales. I use Newton's Rules of Reasoning to argue that we should retain General Relativity as our theory of gravity at galactic and greater scales, despite the lack of positive evidence to confirm it over its rivals at these scales. (shrink)

This textbook covers all the essentials, weaving together the latest theory with the experimental techniques, instrumentation, and observational methods astronomers use to study high-energy radiation from space.

unlikely name of Sanduleak -69 o202 had exploded, becoming type II supernova SN1987A. The discovery was broadcast to a data-hungry world, and the astronomy/astrophysics community has been in an uproar ever since. Sanduleak -69 o202 before exploding had a mass 15-20 times greater than that of our sun and was located in the Large Magellanic Cloud, a sort of suburb of our galaxy some 160,000 light years distant. To the despair of residents of North America, SN1987A is visible only (...) in the southern hemisphere. A friend just back from Argentina tells me that it's still quite visible there and is about as bright as the stars of the Southern Cross constellation. (shrink)

This book provides a compilation of in-depth articles and reviews on key topics within gravitation, cosmology and related issues. It is a celebratory volume dedicated to Prof. Thanu Padmanabhan ("Paddy"), the renowned relativist and cosmologist from IUCAA, India, on the occasion of his 60th birthday. The authors, many of them leaders of their fields, are all colleagues, collaborators and former students of Paddy, who have worked with him over a research career spanning more than four decades. Paddy is a scientist (...) of diverse interests, who attaches great importance to teaching. With this in mind, the aim of this compilation is to provide an accessible pedagogic introduction to, and overview of, various important topics in cosmology, gravitation and astrophysics. As such it will be an invaluable resource for scientists, graduate students and also advanced undergraduates seeking to broaden their horizons. (shrink)

François Arago, the first to show in 1810 that the surface of the Sun and stars is made of incandescent gas and not solid or liquid, was a prominent physicist of the 19th century. He used his considerable influence to help Fresnel, Ampere and others develop their ideas and make themselves known. This book covers his personal contributions to physics, astronomy, geodesy and oceanography, which are far from negligible, but insufficiently known. Arago was also an important and influential political man (...) who, for example, abolished slavery in the French colonies. One of the last humanists, he had a very broad culture and range of interests. In parallel to his biography, this title also covers the spectacular progresses of science at the time of Arago, especially in France: the birth of physical optics, electromagnetism and thermodynamics. Francois Arago's life is a fascinating epic tale that reads as a novel. (shrink)

This paper explores the epistemic status of models and simulations between theory, on the one hand, and observations, on the other. In particular, I will argue that the interpretation of an essentially invariant astrophysical model structure can change substantially over time. I will illustrate this claim using as an example the first 20 years (1985–2004) of development of the Paris-Durham shock code—a numerical model of slow interstellar shock waves (i.e. a disturbance of the medium that travel faster than the local (...) speed of sound). I will show that the model’s interpretation and, in particular, its underlying representational ideal—the modeler’s (often implicit) goal governing the development and the use of the model—changed notably during this period. Whereas the code was originally used in a purely exploratory fashion, it was later taken to represent and encompass the target phenomenon as completely as possible. It is noteworthy that during this transition the model’s change of epistemic status was never explicitly acknowledged or in any way articulated. However, the impetus for the change can, I claim, be found in the role that observational data came to play in the later publications. (shrink)

This paper explores the epistemic status of models and simulations between theory, on the one hand, and observations, on the other. In particular, I will argue that the interpretation of an essentially invariant astrophysical model structure can change substantially over time. I will illustrate this claim using as an example the first 20 years (1985–2004) of development of the Paris-Durham shock code—a numerical model of slow interstellar shock waves (i.e. a disturbance of the medium that travel faster than the local (...) speed of sound). I will show that the model’s interpretation and, in particular, its underlying representational ideal—the modeler’s (often implicit) goal governing the development and the use of the model—changed notably during this period. Whereas the code was originally used in a purely exploratory fashion, it was later taken to represent and encompass the target phenomenon as completely as possible. It is noteworthy that during this transition the model’s change of epistemic status was never explicitly acknowledged or in any way articulated. However, the impetus for the change can, I claim, be found in the role that observational data came to play in the later publications. (shrink)

(1978). Edward C. Pickering, the Henry Draper Memorial, and the beginnings of astrophysics in America. Annals of Science: Vol. 35, No. 4, pp. 365-377.

Recent developments in astrophysical cosmology have revived support for the design argument among a growing clique of astrophysicists. I show that the scientific/mathematical evidence cited in support of intelligent design of the universe is infected with a mathematical sharp practice: the concepts of two numbers being of the same order of magnitude, and of being within an order of each other, have been stretched from their proper meanings so as to doctor the numbers evidentially. This practice started with A. S. (...) Eddington and P. A. M. Dirac in the 1920s and 1930s, but it is still very much alive today. 1 Introduction 2 The birth of a sharp practice 3 High tide for the anthropic principle 4 How not to do things with numbers 5 The recalcitrant sloppiness of crud 6 How excited can excited carbon-12 be? 7 Is a pile of doubts a doubtful pile? 8 Conclusion. (shrink)

The compact and, with \ M\, very massive object located at the center of the Milky Way is currently the very best candidate for a supermassive black hole in our immediate vicinity. The strongest evidence for this is provided by measurements of stellar orbits, variable X-ray emission, and strongly variable polarized near-infrared emission from the location of the radio source Sagittarius A* in the middle of the central stellar cluster. Simultaneous near-infrared and X-ray observations of SgrA* have revealed insights into (...) the emission mechanisms responsible for the powerful near-infrared and X-ray flares from within a few tens to one hundred Schwarzschild radii of such a putative SMBH. If SgrA* is indeed a SMBH it will, in projection onto the sky, have the largest event horizon and will certainly be the first and most important target for very long baseline interferometry observations currently being prepared by the event horizon telescope. These observations in combination with the infrared interferometry experiment GRAVITY at the very large telescope interferometer and other experiments across the electromagnetic spectrum might yield proof for the presence of a black hole at the center of the Milky Way. The large body of evidence continues to discriminate the identification of SgrA* as a SMBH from alternative possibilities. It is, however, unclear when the ever mounting evidence for SgrA* being associated with a SMBH will suffice as a convincing proof. Additional compelling evidence may come from future gravitational wave observatories. This manuscript reviews the observational facts, theoretical grounds and conceptual aspects for the case of SgrA* being a black hole. We treat theory and observations in the framework of the philosophical discussions about “realism and underdetermination”, as this line of arguments allows us to describe the situation in observational astrophysics with respect to supermassive black holes. Questions concerning the existence of supermassive black holes and in particular SgrA* are discussed using causation as an indispensable element. We show that the results of our investigation are convincingly mapped out by this combination of concepts. (shrink)

The dark matter problem in astrophysics exposes an underappreciated weakness in the evidential warrant for General Relativity (GR). The "dark matter double bind" entails that GR gets no differential evidential support from dynamical phenomena occurring at scales larger than our solar system, as compared to members of a significant class of rival gravitation theories. These rivals are each empirically indistinguishable from GR for phenomena taking place at solar system scales, but make predictions that may differ radically from GR's at (...) larger scales. Thus the typical confidence in the universal applicability of GR is insufficiently warranted in the present evidential context. (shrink)

This essay examines the role of amateurs in founding the astronomical subdiscipline of astrophysics. During 1840–1870, they initiated many of the observing programs that came to comprise the new specialty. And during 1870–1910, they participated both in the ongoing research of the field and the campaign to provide it with an institutional base. These general trends are illustrated by examples from the lives of ten prominent amateur solar physicists.

This paper compares four techniques for measuring the masses of galaxies and larger astrophysical systems from their dynamics. The apparent agreement of these techniques is sometimes invoked as reason for hypothesizing the existence of huge quantities of “dark matter” as the best solution to “the dynamical discrepancy”, the 100-fold disparity between the amount of mass visible in large scale astrophysical systems and the amount calculated from dynamics. This paper argues that the agreement, though suggestive, is not definitive. The coincident measurements (...) remain the best reason for preferring dark matter over revisions to General Relativity for solving the dynamical discrepancy, but the resulting warrant for this preference is weak. (shrink)

Theoretical astrophysics emerged as a significant research programme with the construction of a series of stellar models by A. S. Eddington. This paper examines the controversies surrounding those models as a way of understanding the development and justification of new theoretical technologies. In particular, it examines the challenges raised against Eddington by James Jeans, and explores how the two astronomers championed different visions of what it meant to do science. Jeans argued for a scientific method based on certainty and (...) completeness, whereas Eddington called for a method that valued exploration and further investigation, even at the sake of secure foundations. The first generation of stellar models depended on the validity of Eddington's approach – the physics and many of the basic facts of stars were poorly understood and he justified his models through their utility for future research and their robustness under challenging use. What would become theoretical astrophysics depended heavily on this phenomenological outlook, which Jeans dismissed as not even science. This was a dispute about the practice of theory, and it would be this methodological debate that made theoretical astrophysics viable. (shrink)

We discuss three philosophically interesting epistemic peculiarities of black hole astrophysics: (1) issues concerning whether and in what sense black holes do exist; (2) how to best approach multiplicity of available definitions of black holes; (3) short (i.e., accessible within an individual human lifespan) dynamical timescales present in many of the recent, as well as prospective, observations involving black holes. In each case we argue that the prospects for our epistemic situation are optimistic.

In the early 1880s, Henri Poincaré discovered an equilibrium figure for uniformly-rotating fluid masses—the pear, or piriform figure—and speculated that in certain circumstances the pear splits into two unequal parts, and provides thereby a model for the origin of binary stars. The contemporary emergence of photometric and spectroscopic studies of variable stars fueled the first models of eclipsing binaries, and provided empirical support for a realist view of equilibrium figures—including the pear—in the cosmic realm. The paper reviews astrophysical interpretation of (...) the Poincaré pear and the Poincaré-Darwin fission hypothesis with respect to research on variable stars from 1885 to 1901. (shrink)