On the orthodox interpretation of bounce cosmologies, a preceding universe was compressed to a small size before “bouncing” to form the present expanding universe. William Lane Craig and James Sinclair have argued that the orthodox interpretation is incorrect if the entropy reaches a minimum at the bounce. In their view, the interface between universes represents the birth of two expanding universes, i.e., a “double bang” instead of a “big bounce”. Here, I reply to Craig and Sinclair in defense of the (...) orthodox interpretation. Contrary to their interpretation, features of one universe explain features of the other universe and so must precede the other universe in time. Moreover, contrary to a crucial part of Craig and Sinclair’s interpretation, there are bounce cosmologies in which the thermodynamic arrow of time is continuous through the bounce even though the entropy is “reset” at the bounce. (shrink)

A short review of some recent developments in the philosophy of physics is presented. I focus on themes which illustrate relations and points of common interest between philosophy of physics and three of its `neighboring' elds: Physics, metaphysics and general philosophy of science. The main examples discussed in these three `border areas' are decoherence and the interpretation of quantum mechanics; time in physics and metaphysics; and methodological issues surrounding the multiverse idea in modern cosmology.

info:eu-repo/semantics/publishedVersion.

The essay revisits the puzzle of the ‘passage’ of time in relation to EPR-type measurements and asks what philosophical consequences can be drawn from them. Some argue that the lack of invariance of temporal order in the measurement of a space-like related EPR pair, under relativistic motion, casts serious doubts on the ‘reality’ of the lapse of time. Others argue thatcertain features of quantum mechanics establisha tensed theory of time – understood here as Possibilism or the growing block universe. The (...) paper analyzes the employment of frame-invariant entropic clocks in a relativistic setting and argues that tenselessness does not imply timelessness. But this conclusion does not support a tensed theory of time, which requires a preferred foliation. It is argued that the only reliable inference from the EPR example and the use of entropic clocks is an inference not just to a Leibnizian order of the succession of events but a frame-invariant order according to some selected clocks. (shrink)

One of the few authors to have explicitly connected the physical issue of the expansion of the universe with the philosophical topic of the metaphysical status of space is Gerald James Whitrow. This paper examines his view and tries to highlight its strong and weak points, thereby clarifying its obscure aspects. In general, this really interesting philosophical approach to one of the most important phenomena concerning our universe, and therefore modern cosmology, has been very rarely tackled. This unicity increases the (...) value, from a physical, philosophical and historical point of view, of Whitrow’s attempt and calls for new research. (shrink)

I discuss how modern cosmology illustrates underdetermination of theoretical hypotheses by data, in ways that are different from most philosophical discussions. I confine the discussion to the history of the observable universe from about one second after the Big Bang, as described by the mainstream cosmological model: in effect, what cosmologists in the early 1970s dubbed the ‘standard model’, as elaborated since then. Or rather, the discussion is confined to a (very!) few aspects of that history. I emphasize that despite (...) the underdetermination, a scientific realist can, and should, endorse this description. (shrink)

I discuss how modern cosmology illustrates under-determination of theoretical hypotheses by data, in ways that are different from most philosophical discussions. I emphasise cosmology's concern with what data could in principle be collected by a single observer ; and I give a broadly sceptical discussion of cosmology's appeal to the cosmological principle as a way of breaking the under-determination.I confine most of the discussion to the history of the observable universe from about one second after the Big Bang, as described (...) by the mainstream cosmological model: in effect, what cosmologists in the early 1970s dubbed the ‘standard model’, as elaborated since then. But in the closing Section 4, I broach some questions about times earlier than one second. (shrink)

This inaugural handbook documents the distinctive research field that utilizes history and philosophy in investigation of theoretical, curricular and pedagogical issues in the teaching of science and mathematics. It is contributed to by 130 researchers from 30 countries; it provides a logically structured, fully referenced guide to the ways in which science and mathematics education is, informed by the history and philosophy of these disciplines, as well as by the philosophy of education more generally. The first handbook to cover the (...) field, it lays down a much-needed marker of progress to date and provides a platform for informed and coherent future analysis and research of the subject. -/- The publication comes at a time of heightened worldwide concern over the standard of science and mathematics education, attended by fierce debate over how best to reform curricula and enliven student engagement in the subjects There is a growing recognition among educators and policy makers that the learning of science must dovetail with learning about science; this handbook is uniquely positioned as a locus for the discussion. -/- The handbook features sections on pedagogical, theoretical, national, and biographical research, setting the literature of each tradition in its historical context. Each chapter engages in an assessment of the strengths and weakness of the research addressed, and suggests potentially fruitful avenues of future research. A key element of the handbook’s broader analytical framework is its identification and examination of unnoticed philosophical assumptions in science and mathematics research. It reminds readers at a crucial juncture that there has been a long and rich tradition of historical and philosophical engagements with science and mathematics teaching, and that lessons can be learnt from these engagements for the resolution of current theoretical, curricular and pedagogical questions that face teachers and administrators. (shrink)

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 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 : 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 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 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 concerns difficulties about confirming a cosmological theory that postulates a multiverse, i.e. a set of domains each of whose inhabitants 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. (shrink)

Norton (2003 and 2006) has recently argued that causation is merely a useful folk concept and that it fails to hold for some simple systems even in the supposed paradigm case of a causal physical theory – namely Newtonian mechanics. The purpose of this article is to argue against this devaluation of causality in physics. My main argument is that Norton’s alleged counterexample to causality (and determinism) within standard Newtonian physics fails to obey what I shall call the causal core (...) of Newtonian mechanics. In particular, I argue, Norton’s example is not in conformity with Newton’s first law. Moreover, Norton’s reformulation of this first law (in an instantaneous form) seems insufficient as a replacement for the original version since the notion of inertial frames in the resulting reformulated theory lacks a physical justification, and since an intelligible notion of time in Newtonian mechanics appears to be closely tied to Newton’s first law in its standard form. I will finally suggest how, given a plausible relationist account of time, the causal core of Newtonian mechanics may play a central role also in relativity and quantum theory. (shrink)

According to conventional wisdom, local gauge symmetry is not a symmetry of nature, but an artifact of how our theories represent nature. But a study of the so-called theta-vacuum appears to refute this view. The ground state of a quantized non-Abelian Yang-Mills gauge theory is characterized by a real-valued, dimensionless parameter theta—a fundamental new constant of nature. The structure of this vacuum state is often said to arise from a degeneracy of the vacuum of the corresponding classical theory, which degeneracy (...) allegedly arises from the fact that “large” (but not “small”) local gauge transformations connect physically distinct states of zero field energy. If that is right, then some local gauge transformations do generate empirical symmetries. In defending conventional wisdom against this challenge I hope to clarify the meaning of empirical symmetry while deepening our understanding of gauge transformations. I distinguish empirical from theoretical symmetries. Using Galileo’s ship and Faraday’s cube as illustrations, I say when an empirical symmetry is implied by a theoretical symmetry. I explain how the theta-vacuum arises, and how “large” gauge transformations differ from “small” ones. I then present two analogies from elementary quantum mechanics. By applying my analysis of the relation between empirical and theoretical symmetries, I show which analogy faithfully portrays the character of the vacuum state of a classical non-Abelian Yang-Mills gauge theory. The upshot is that “large” as well as “small” gauge transformations are purely formal symmetries of non-Abelian Yang-Mills gauge theories, whether classical or quantized. It is still worth distinguishing between these kinds of symmetries. An analysis of gauge within the constrained-Hamiltonian formalism yields the result that “large” gauge transformations should not be classified as gauge transformations; indeed, nor should “global” gauge transformations. In a theory in which boundary conditions are modeled dynamically, “global” gauge transformations may be associated with physical symmetries, corresponding to translations of these extra dynamical variables. Such translations are symmetries if and only if charge is conserved. But it is hard to argue that these symmetries are empirical, and in any case they do not correspond to any constant phase change in a quantum state. (shrink)

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 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 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. 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. (shrink)

We examine the necessary physical underpinnings for setting up the cosmological standard model with a global cosmic time parameter. In particular, we discuss the role of Weyl's principle which asserts that cosmic matter moves according to certain regularity requirements. After a brief historical introduction to Weyl's principle we argue that although the principle is often not explicitly mentioned in modern standard texts on cosmology, it is implicitly assumed and is, in fact, necessary for a physically well-defined notion of cosmic time. (...) We finally point out that Weyl's principle might be in conflict with the wide-spread idea that the universe at some very early stage can be described exclusively in terms of quantum theory. (shrink)

In recent analyses of standard, single-universe, cosmology, it was pointed out that specific assumptions regarding the distribution and motion of matter must be made in order to set up the cosmological standard model with a global time parameter. Relying on these results, we critically examine the notion of time in the multiverse, and in particular the idea that some parts of the multiverse are older than others. By focusing on the most elaborated multiverse proposal in cosmology, the inflationary multiverse, we (...) identify three problems for establishing a physically well-defined notion of global time; a quantum problem, a collision problem and a fractal problem. The quantum problem, and the closely related ``cosmic measurement problem", may even undermine the idea that parts of the multiverse causally and temporally precede our universe. (shrink)