John Earman

Bangs, crunches, whimpers, and shrieks : singularities and acausalities in relativistic spacetimes

1. Introducing Spacetime Singularities and Acausalities 2. Defining, Characterizing, and Proving the Existence 3. Cosmic Censorship 4. Supertasks 5. The Big Bang and the Horizon Problem 6. Time Travel 7. Eternal Recurrence, Cyclic Time, and All That 8. Afterword

CETERIS PARIBUS, THERE IS NO PROBLEM OF PROVISOS

Much of the literature on ceteris paribus laws is based on a misguided egalitarianism about the sciences. For example, it is commonly held that the special sciences are riddled with ceteris paribus laws; from this many commentators conclude that if the special sciences are not to be accorded a second class status, it must be ceteris paribus all the way down to fundamental physics. We argue that the (purported) laws of fundamental physics are not hedged by ceteris paribus clauses and provisos. Furthermore, we show that not only is there no persuasive analysis of the truth conditions for ceteris paribus laws, there is not even an acceptable account of how they are to be saved from triviality or how they are to be melded with standard scientific methodology. Our way out of this unsatisfactory situation to reject the widespread notion that the achievements and the scientific status of the special sciences must be understood in terms of ceteris paribus laws.

Forever is a Day: Supertasks in Pitowsky and Malament-Hogarth Spacetimes

The standard theory of computation excludes computations whose completion requires an infinite number of steps. Malament-Hogarth spacetimes admit observers whose pasts contain entire future-directed, timelike half-curves of infinite proper length. We investigate the physical properties of these spacetimes and ask whether they and other spacetimes allow the observer to know the outcome of a computation with infinitely many steps.

Relativity and Eclipses: The British Eclipse Expeditions of 1919 and Their Predecessors

La deviation gravitionnelle de la lumiere verifiee en photographiant une eclipse du soleil (Campbell, Eddington).

Laws, Symmetry, and Symmetry Breaking: Invariance, Conservation Principles, and Objectivity

Given its importance in modern physics, philosophers of science have paid surprisingly little attention to the subject of symmetries and invariances, and they have largely neglected the subtopic of symmetry breaking. I illustrate how the topic of laws and symmetries brings into fruitful interaction technical issues in physics and mathematics with both methodological issues in philosophy of science, such as the status of laws of physics, and metaphysical issues, such as the nature of objectivity.

EXORCIST XIV: The Wrath of Maxwell's Demon. Part II. From Szilard to Landauer and Beyond

In this second part of our two-part paper we review and analyse attempts since 1950 to use information theoretic notions to exorcise Maxwell’s Demon. We argue through a simple dilemma that these attempted exorcisms are ine⁄ective, whether they follow Szilard in seeking a compensating entropy cost in information acquisition or Landauer in seeking that cost in memory erasure. In so far as the Demon is a thermodynamic system already governed by the Second Law, no further supposition about information and entropy is needed to save the Second Law. In so far as the Demon fails to be such a system, no supposition about the entropy cost of information acquisition and processing can save the Second Law from the Demon. ( 1999 Elsevier Science Ltd. All rights reserved.

Curie's Principle and spontaneous symmetry breaking

In 1894 Pierre Curie announced what has come to be known as Curies Principle: the asymmetry of effects must be found in their causes. In the same publication Curie discussed a key feature of what later came to be known as spontaneous symmetry breaking: the phenomena generally do not exhibit the symmetries of the laws that govern them. Philosophers have long been interested in the meaning and status of Curies Principle. Only comparatively recently have they begun to delve into the mysteries of spontaneous symmetry breaking. The present paper aims to advance the discussion of both of these twin topics by tracing their interaction in classical physics, ordinary quantum mechanics and quantum field theory. The features of spontaneous symmetry that are peculiar to quantum field theory have received scant attention in the philosophical literature. These features are highlighted here, along with an explanation of why Curies Principle, though valid in quantum field theory, is nearly vacuous in that context.

Exorcist XIV: The wrath of Maxwell's demon. Part I. from Maxwell to szilard

In this first part of a two-part paper, we describe efforts in the early decades of this century to restrict the extent of violations of the Second Law of thermodynamics that were brought to light by the rise of the kinetic theory and the identification of fluctuation phenomena. We show how these efforts mutated into Szilard’s (1929) proposal that Maxwell’s Demon is exorcised by proper attention to the entropy costs associated with the Demon’s memory and information acquisition. In the second part we will argue that the information theoretic exorcisms of the Demon provide largely illusory benefits. According to the case, they either return a presupposition that can be had without information theoretic consideration or they postulate a broader connection between information and entropy than can be sustained.

Why Ergodic Theory Does Not Explain the Success of Equilibrium Statistical Mechanics

We argue that, contrary to some analyses in the philosophy of science literature, ergodic theory falls short in explaining the success of classical equilibrium statistical mechanics. Our claim is based on the observations that dynamical systems for which statistical mechanics works are most likely not ergodic, and that ergodicity is both too strong and too weak a condition for the required explanation: one needs only ergodic-like behaviour for the finite set of observables that matter, but the behaviour must ensure that the approach to equilibrium for these observables is on the appropriate time-scale.

ASPECTS OF DETERMINISM IN MODERN PHYSICS

The aims of this chapter are to review some aspects of determinism that are familiar to physicists but are little discussed in the philosophical literature and to show how these aspects connect determinism to issues about symmetries in physics, the structure and ontological status of spacetime, predictability, and computability. 1 It will emerge that in some respects determinism is a robust doctrine and is quite hard to kill, while in other respects it is fragile and requires various enabling assumptions to give it a fighting chance. It will also be seen that determinism is far from a dead issue. Whether or not ordinary non-relativistic quantum mechanics (QM) admits a viable deterministic underpinning is still a matter of debate. Less well known is the fact that in some cases QM turns out to be more deterministic than its classical counterpart. Quantum field theory (QFT) assumes determinism, at least at the classical level, in order to construct the field algebra of quantum observables. Determinism is at the heart of the cosmic censorship hypothesis, the most important unsolved issue in classical general relativity theory (GTR). And issues about the nature and status of determinism lie at the heart of key foundation issues in the search for a theory of quantum gravity.