Published online by Cambridge University Press: 01 April 2022
Much controversy surrounds the question of what ought to be the proper definition of ‘singularity’ in general relativity, and the question of whether the prediction of such entities leads to a crisis for the theory. I argue that a definition in terms of curve incompleteness is adequate, and in particular that the idea that singularities correspond to ‘missing points’ has insurmountable problems. I conclude that singularities per se pose no serious problem for the theory, but their analysis does bring into focus several problems of interpretation at the foundation of the theory often ignored in the philosophical literature.
This paper began life as a small criticism of a few points John Earman makes in Chapter 2 of his book Bangs, Crunches, Whimpers and Shrieks, and grew as I grew to realize more fully the complexity and subtlety of the issues involved. I shall not always point out where I am in agreement or disagreement with Earman, much less always discuss why this is so, though I shall try to on the most important points. The reader ought to keep in mind, though, that Earman's book is the constant foil lurking in the background. I thank R. Geroch and D. Malament for stimulating conversations on all these topics. I am also grateful to M. Dorato for writing a review of Earman 1995 that made me realize the need to reread it and think more about singular structure, and to the History and Philosophy of Science Department at Pittsburgh, where I presented an earlier, briefer, version of this paper in a colloquium, for stimulating questions.