On under-determination in cosmology

Butterfield, Jeremy

doi:10.1016/j.shpsb.2013.06.003

Cited by 27 publications

(11 citation statements)

References 38 publications

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“…Roughly, space-time (M, g µν ) is observationally indistinguishable from some numerically distinct space-time (M ′ , g ′ µν ) just in case any observer at any arbitrarily chosen point in (M, g µν ) cannot determine, from any of the data in their past light cone, which of the two spacetimes they inhabit (Manchak, 2011, 412). As the Manchak-Malament theorem has established (Malament (1977); Manchak (2009); also see Beisbart (2009); Butterfield (2014); Manchak (2021); Norton (2011)), the members of a fairly broad class of space-times are observationally indistinguishable from numerically distinct space-times.…”

Section: Identifying the Universe's Past Boundarymentioning

confidence: 99%

Neo-Lorentzian Relativity and the Beginning of the Universe

Linford¹

2021

Preprint

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Many physicists have thought that absolute time became otiose with the introduction of Special Relativity. William Lane Craig disagrees. Craig argues that although relativity is empirically adequate within a domain of application, relativity is literally false and should be supplanted by a Neo-Lorentzian alternative that allows for absolute time. Meanwhile, Craig and co-author James Sinclair have argued that physical cosmology supports the conclusion that physical reality began to exist at a finite time in the past. However, on their view, the beginning of physical reality requires the objective passage of absolute time, so that the beginning of physical reality stands or falls with Craig's Neo-Lorentzian metaphysics. Here, I raise doubts about whether, given Craig's NeoLorentzian metaphysics, physical cosmology could adequately support a beginning of physical reality within the finite past. Craig and Sinclair's conception of the beginning of the universe requires a past boundary to the universe. A past boundary to the universe cannot be directly observed and so must be inferred from the observed matter-energy distribution in conjunction with auxilary hypotheses drawn from a substantive physical theory. Craig's brand of Neo Lorentzianism has not been sufficiently well specified so as to infer either that there is a past boundary or that the boundary is located in the finite past. Consequently, Neo Lorentzianism implicitly introduces a form of skepticism that removes the ability that we might have otherwise had to infer a beginning of the universe. Furthermore, in analyzing traditional big bang models, I develop criteria that Neo-Lorentzians should deploy in thinking about the direction and duration of time in cosmological models generally. For my last task, I apply the same criteria to bounce cosmologies and show that Craig and Sinclair have been wrong to interpret bounce cosmologies as including a beginning of physical reality.

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Section: Identifying the Universe's Past Boundarymentioning

confidence: 99%

Neo-Lorentzian Relativity and the Beginning of the Universe

Linford¹

2021

Preprint

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“…[Indeed, the title of Guth's original paper explicitly refers to the problems in (i) and (ii).] The manner in which the expansion solves these problems is well known [see, for example, Kolb and Turner (1990) and Linde (1990)], and the solutions have also attracted philosophical attention (Earman, 1995;Earman and Mosterin, 1999;Smeenk, 2013;Butterfield, 2014;McCoy, 2015;Azhar and Loeb, 2019).…”

Section: Claimed Virtuesmentioning

confidence: 99%

Effective field theories as a novel probe of fine-tuning of cosmic inflation

Azhar¹

2019

Preprint

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The leading account of several salient observable features of our universe today is provided by the theory of cosmic inflation. But an important and thus far intractable question is whether inflation is generic, or whether it is finely tuned-requiring very precisely specified initial conditions. In this paper I argue that a recent, model-independent characterization of inflation, known as the 'effective field theory (EFT) of inflation', promises to address this question in a thoroughly modern and significantly more comprehensive way than in the existing literature.To motivate and provide context for this claim, I distill three core problems with the theory of inflation, which I dub the permissiveness problem, the initial conditions problem, and the multiverse problem. I argue that the initial conditions problem lies within the scope of EFTs of inflation as they are currently conceived, whereas the other two problems remain largely intractable: their solution must await a more complete description of the very early universe. I highlight recent work that addresses the initial conditions problem within the context of a dynamical systems analysis of a specific (state-of-the-art) EFT of inflation, and conclude with a roadmap for how such work might be extended to realize the promise claimed above.

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“…To do this, they only need laws governing the parts of their subject-matter relevant to their descriptive and explanatory aims: they do not need laws whose instances are universes, or Earths. Thus cosmology is no more impugned as a science by the existence of only one universe, than geology is by the existence of only one planet Earth (Cleland 2002, Butterfield 2012. (Agreed: with the discovery of exoplanets, 'geology' might come to mean the science of all planets, or of all Earth-like planets.…”

Section: No Laws Of Cosmology? No Worriesmentioning

confidence: 99%

Scientific Realism and Primordial Cosmology

Azhar¹,

Butterfield²

2017

The Routledge Handbook of Scientific Realism

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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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On under-determination in cosmology

Cited by 27 publications

References 38 publications

Neo-Lorentzian Relativity and the Beginning of the Universe

Neo-Lorentzian Relativity and the Beginning of the Universe

Effective field theories as a novel probe of fine-tuning of cosmic inflation

Scientific Realism and Primordial Cosmology

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