Black hole voyeurism

Alexander Smith and Robert Mann

Alexander (right) is a PhD student in the department of Physics & Astronomy at the University of Waterloo. Robert (left), a past-president of the Canadian Association of Physicists, is a senior professor in the department of Physics & Astronomy and the department of Applied Mathematics at the University of Waterloo and an affiliate at the Perimeter Institute.

Could a quantum detector peek inside a black hole?

It has long been known that the thermal radiation emitted by a black hole can be detected by a particle detector, and even today the details of this process are an active area of research. But are such detectors sensitive to the interior structure of black holes? From a classical perspective, conventional wisdom would suggest not: the topological censorship theorem relegates all isolated topological structures (such as wormholes, topological knots, etc) to be hidden behind a horizon and thus inaccessible to observers by classical probes. But Continue reading

Discrete wave operator for causets

Joseph Samuel

Joseph Samuel is an Editorial Board member of Classical and Quantum Gravity and a Professor at the Raman Research Institute, Bangalore, India

This paper leads to a discrete action functional on causets.

Lisa Glaser presents some tidy results in the definition of the discrete d’Alembertian operator on a causet in any dimension.

The causet approach to quantum gravity was pioneered by Rafael Sorkin in the 1980s. It approximates the space-time continuum by a discrete structure–a set with a partial order. The causet approach is marked by its minimalist philosophy, capturing Lorentzian manifolds in a discrete net with just Continue reading