Foundations of Physics
Dr Eric Cavalcanti
School of Physics
A28 - Physics
The University of Sydney
NSW 2006 Australia
phone: +61 2 9351 3982
fax: +61 2 9351 7726
In line with the openness of the foundations of physics to related disciplines, the cluster has nodes both at the Department of Physics and the Department of History and Philosophy of Science. It has close links to groups at the University of Oxford, Griffith University, University of Queensland and the Perimeter Institute in Canada. The group has also recently begun an interdisciplinary project, funded by the John Templeton Foundation: New Agendas for the Study of Time: Connecting the Disciplines (see below).
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.
New Agendas for the Study of Time: Connecting the Disciplines
Nothing is more fundamental than time in human life. Yet time remains profoundly mysterious. Some of its deepest puzzles issue from the fact that it isn’t clear just where, across a very wide range of intellectual enquiry, it is best investigated. Some aspects certainly belong to physics. But even within physics, there is deep disagreement about which aspects of the ordinary view of time we should expect to find in physical theory. The overriding objective of this project is thus to give researchers from a range of disciplines a deeper understanding of what aspects of the study of time fruitfully belong to their own discipline, and how those aspects both relate to, and are distinct from, the issues that belong to other disciplines. In achieving this, we hope to bring a new clarity to the study of time, in its most global sense; and set the agenda for the future of the subject, in a way that would be impossible without this project’s interdisciplinary imperative.
The Development of Quantum Gravity
This research project constitutes the first large-scale effort to unpack and make sense of the historical development of quantum gravity. Given the pressing nature of this problem in physics, and its importance for our worldview, such a study would be of great benefit to several sectors of the academic community. By giving a global perspective of the field from its origins early in the 20th Century, those outside the field will be able to appreciate its importance and its place in contemporary physics. Quantum gravity researchers will be able to see how their preferred approach fits into the web of research programmes, thus opening the door for greater collaboration between the various approaches. Philosophers of science will gain some insight into the physical and mathematical principles that have guided the field throughout its existence.
Research on quantum foundations was instrumental in the development of the fields of quantum information and computation. Quantum cryptography, quantum teleportation and quantum computation all have roots in foundational thinking. In recent years, an opposite trend seems to be developing. The skills gained in thinking about practical problems like computational speed up or secure communication, allied with a rich history of philosophical debate, are leading to new insights about the nature of the theory itself. Ultimately, it is hoped that these insights will lead not only to new ways to explore quantum mechanics for information processing, but to a new conceptual understanding of the abstract formalism.
Project topics include ontological models, quantum reference frames, generalised probabilistic theories, causal networks, entanglement, Einstein-Podolsky-Rosen steering and Bell-nonlocality, closed timelike curves and nonlinear extensions of quantum theory.