Before the discovery of the expanding universe, one of the challenges faced in early relativistic cosmology was the determination of the finite and constant curvature radius of space-time by using astronomical observations. Great interest in this specific question was shown by de Sitter, Silberstein, and Lundmark. Their ideas and methods for measuring the cosmic curvature radius, at that time interpreted as equivalent to the size of the universe, contributed to the development of the empirical approach to relativistic cosmology. Their works (...) are a noteworthy example of the efforts made by modern cosmologists toward the understanding of the universe as a whole, its properties, and its content. (shrink)

I review some theoretical ideas in cosmology different from the standard “Big Bang”: the quasi-steady state model, the plasma cosmology model, non-cosmological redshifts, alternatives to non-baryonic dark matter and/or dark energy, and others. Cosmologists do not usually work within the framework of alternative cosmologies because they feel that these are not at present as competitive as the standard model. Certainly, they are not so developed, and they are not so developed because cosmologists do not work on them. It is a (...) vicious circle. The fact that most cosmologists do not pay them any attention and only dedicate their research time to the standard model is to a great extent due to a sociological phenomenon . We might well wonder whether cosmology, our knowledge of the Universe as a whole, is a science like other fields of physics or a predominant ideology. (shrink)

This article looks at Vesto Slipher’s work on nebular spectroscopy between 1912 and 1922as well as related research by other astronomers of the period, and it examines the dissem-ination of their results more widely. Slipher’s observations are viewed as marking the di-viding line between speculation about the universe in traditional astronomy and theadvent of modern cosmology and the theory of an expanding universe. The intent is todocument the dissemination of Slipher’s results in the period leading up to the publicationof studies (...) of relativistic cosmology by Willem de Sitter in 1917 and Alexander Friedmannin 1922. Themes touched on in the article include the unprecedented character ofSlipher’sfindings and the interaction of observation and theory in modern cosmology.A prominent concern is the role of technology in astronomical science over the past cen-tury and a half. Here reference is made to the writings of Paul Forman on historical shiftsthat have taken place in our understanding of the relationship of science and technology. (shrink)

If cosmology is to obtain knowledge about the whole universe, it faces an underdetermination problem: Alternative space-time models are compatible with our evidence. The problem can be avoided though, if there are good reasons to adopt the Cosmological Principle (CP), because, assuming the principle, one can confine oneself to the small class of homogeneous and isotropic space-time models. The aim of this paper is to ask whether there are good reasons to adopt the Cosmological Principle in order to avoid underdetermination (...) in cosmology. Various strategies to justify the CP are examined. For instance, arguments to the effect that the truth of the CP follows generically from a large set of initial conditions; an inference to the best explanation; and an inductive strategy are assessed. I conclude that a convincing justification of the CP has not yet been established, but this claim is contingent on a number of results that may have to be revised in the future. (shrink)

This article focuses on the multifaceted and thematic nature expressed by the concept of creation in 20th-century cosmology, namely in the construction of the big bang cosmology and its rival, the steadystate cosmology. Regarding the approaches of three of the main founders of big bang cosmology, we can find, in an explicit or implicit way, two different forms of creation – creation from nothing or creation from shapeless matter. On the opposite side, suggested by the proponents of steady-state cosmology, we (...) can find another form of creation – the continuous creation of matter. It is proposed that the multifaceted concept of creation, due to the wide interest it aroused and the intensity of cosmological debates it provoked, as well as its historical longevity and its disciplinary and cultural transversality, may be recognized as a thema. (shrink)

When philosophers, poets or astronomers have tried to comprehend the vastness of the universe, from early times to the present days, the possibility of an infinite universe has appeared as an appealing speculation. Although, we do not yet have a compelling answer to the question: “is the universe infinite?” our present cosmological knowledge provides us with some clues to delineate which is the most likely answer. This contribution aims to address this question from the point of view of the history (...) of thought, from the ancient philosophers to the present astronomers, taking into account the interweaving relationship between scientific knowledge and culture. Its connection with the solutions to the so–called Olbers' paradox will be analysed in detail, including those appearing in literary works, like the prose poem Eureka by Edgar Alan Poe. (shrink)

The history of the dark matter problem can be traced back to at least the 1930s, but it was not until the early 1970s that the issue of ‘missing matter’ was widely recognized as problematic. In the latter period, previously separate issues involving missing mass were brought together in a single anomaly. We argue that reference to a straightforward accumulation of evidence alone is inadequate to comprehend this episode. Rather, the rise of cosmological research, the accompanying renewed interest in the (...) theory of relativity and changes in the manpower division of astronomy in the 1960s are key to understanding how dark matter came to matter. At the same time, this story may also enlighten us on the methodological dimensions of past practices of physics and cosmology. (shrink)