Foundations of Physics
Dr Stephen Bartlett
School of Physics
Room 317
A28 - Physics
The University of Sydney
NSW 2006 Australia
phone: +61 2 9351 3169
fax: +61 2 9351 7726
http://physics.usyd.edu.au/~bartlett
In line with the openness of the foundations of physics to related disciplines, the cluster has close links to both the Department of Physics and the Department of History and Philosophy of Science, and has been approached by the Perimeter Institute (Waterloo, Ontario), one of the main institutes of theoretical physics in Canada, about instituting an international collaboration. This projected collaboration will include in addition also physics groups at the University of Queensland and at Griffiths University.
The two main fields of research currently in this cluster are: the direction of time and quantum theory.
Direction of Time
The problem of the direction of time consists in the apparent contradiction between the time-symmetry (or some appropriate generalisation) of the fundamental laws of physics, which is generally assumed to hold, and the disproportionate occurrence of phenomena displaying one specific direction of time. Examples of such 'arrows of time' abound in physics: temperatures tend to equilibrate, circular waves in a pond spread outwards, the universe appears to expand, the quantum wave function 'collapses', and champagne corks pop; but they are found also more widely: we remember the past and deliberate about the future, death follows birth, effects follow causes. The question of the direction of time thus not only occurs as a conceptual issue within physics, but is a likely link between issues in the foundations of physics and wider philosophical issues. This network of issues has already been the subject of much successful research within the existing Centre for Time.
Quantum Theory
Conceptual issues in quantum theory stretch well beyond the apparent time asymmetry of the so-called 'collapse of the wave function', i.e. the apparent random discontinuity in the behaviour of quantum systems observed upon measurement. The difficulty of reconciling the fundamental equations of the theory with the appearance of the classical world around us (including measuring apparatuses) has prompted the development of several fundamentally different approaches to the theory, ranging from proposed modifications of the theory (so-called spontaneous collapse models) to radical re-interpretations of its meaning (in particular the so-called many-worlds interpretations). Philosophical 'lessons' taken from quantum theory will typically depend crucially on the approach taken. All of these approaches involve both physical and philosophical aspects, and also the research in this field constitutes a meeting point between the two disciplines (not to forget the history of the interpretational debates in quantum theory).