From empirical practice to observables and the action principle

Physical theories ought to be built up from colloquial notions such as ’long bodies’, ’energetic sources’ etc. in terms of which one can define pre-theoretic ordering relations such as ’longer than’, ’more energetic than’. One of the questions addressed in previous work is how to make the transition from these pre-theoretic notions to quantification, such as making the transition from the ordering relation of ’longer than’ (if one body covers the other) to the notion of how much longer.

Weak values: their meaning and uses in quantum foundations.

Weak values were introduced by Aharonov, Albert, and Vaidman 25 years ago, but it is only in the last 10 years that they have begun to enter into mainstream physics. I will introduce weak values as done by AAV, but then give them a modern definition in terms of generalized measurements. I will discuss their properties and their uses in experiment. Finally I will talk about what they have to contribute to quantum foundations. 

Time, cosmology and quantum foundations


Characterizing quantum non-locality: a histories approach

Characterising quantum non-locality using simple physical principles has become a hot topic in quantum foundations of late.  In the simpler case of local hidden variable models, the space of allowed correlations can be characterised by requiring that there exists a joint probability distribution over all possible experimental outcomes, from which the experimental probabilities arise as marginals.  This follows from Bell’s causality condition.  But the existing characterisations of quantum correlations are far from being so straightforward.

Completing Canonical Quantization

The process of canonical quantization:is reexamined with the goal of
ensuring there is only one reality, where $\hbar>0$, in which classical
and quantum theories coexist. Two results are a clarification of the effect of
canonical coordinate transformations and the role of Cartesian coordinates.
Other results provide validation

From Pauli's Principle to Fermionic Entanglement

The Pauli exclusion principle is a constraint on the
natural occupation numbers of fermionic states. It has been suspected for
constraints on these numbers, generalizing the Pauli principle. Surprisingly,
physics is governed by these constraints?


Quantum measurements constrained by symmetry

The Wigner-Araki-Yanase (WAY) theorem delineates
circumstances under which a class of quantum measurements is ruled out.
not commuting with an additive conserved quantity of a quantum system and
measuring apparatus combined admits no repeatable measurements. I'll review the
content of this theorem and present some new work which generalises and
strengthens the existing results.

Laws of thermodynamics beyond the von Neumann regime

A recent development in
information theory is the generalisation of quantum Shannon information theory
to the operationally motivated smooth entropy information theory, which
steps have been taken towards creating a statistical mechanics based on smooth
questions one might not have thought were possible in statistical mechanics,