Events

Singular Regions of Spacetime

In this talk, I revisit the problem of defining spacetime singularities in classical general relativity. In particular, I will argue that spacetime singularities are not objects, but properties of spacetime regions. I will also argue that there is no unique, best definition of a singular region of spacetime; there is, however, a schema that any adequate definition instantiates. Moreover, the question of what particular instantiation of the schema is adequate is intimately connected to the question of what kind of curves represent trajectories of possible observers in “physically reasonable” motion. Then, I will argue that for any instance of the definition schema, “being singular” is best conceptualized as an extrinsic, non-local, but nevertheless localizable (and hence non-global) property of spacetime regions. As a part of that argument, I will discuss various senses in which spacetime regions can be “small”, and show that according to two well-motivated ways of measuring “smallness” of spacetime regions, every singular spacetime has a small singular region.

Monday, November 16, 2026 9:30 AM

Inperson
Speaker will be in person – BHI Conference Room

Virtual
Zoom