January 2023

Modern physics has taught us that space and time are described by different “theories of geometry” in different regimes, from Galilean spacetime in Newtonian mechanics to semi-Riemannian manifolds in general relativity. In a very similar, but less well-known sense, classical probability theory and quantum theory (QT) are special cases in a large landscape of “theories …

Markus Müller
  IQOQI Vienna

How spacetime constrains the structure of quantum theory Read More »

In the standard Fock representation, the 1-photon Hilbert space is spanned by positive frequency, source-free solutions of Maxwell’s equations. The quantum information they carry corresponds precisely to the two radiative modes of the Maxwell fields.  However, this Fock representation is inadequate in a number of physical situations involving sources, and one then has to use appropriate non-Fock representations. …

Abhay Ashtekar
Pennsylvania State University

The many faces of photons Read More »

It has been occasionally remarked, but insufficiently appreciated, that there are two distinct sorts of endeavour that have gone by the name of “thermodynamics”. The first, which is in line with how the founders of the subject thought of it, is a theory about how agents with limited means of manipulation and limited access to …

Wayne Myrvold
Western University

A Tale of Two Sciences, Both Called “Thermodynamics” Read More »