Time and Matter 2007

Session

Quantum Gravity

V

28 Aug 2007, 11:45

Bled, Slovenia

20. Conceptual Problems in Canonical Quantum Gravity and Cosmology

Prof. Claus Kiefer (Univ. Koln, Germany)

28/08/2007, 11:45

Canonical quantization is among the main approaches to quantum gravity. Its main conceptual problems are reviewed in my talk. Most of them are centred around the problem of time: a time parameter is absent in the fundamental equations. I discuss the meaning of time in full quantum gravity and the recovery of semiclassical time as an approximation. This also includes the Hilbert-space...

23. Timeless Records Approach to the Problem of Time in Quantum Gravity

Dr Edward Anderson (Univ. of Cambridge, UK)

28/08/2007, 14:30

The problem of time is a major conceptual stumbling block in attempting to quantize gravity. For, time is conceptually different in general relativity and in conventional quantum theory, which are the two structures that one would seek to combine in forming a theory of quantum gravity. I consider the timeless records approach to this in this seminar. Records are localized,...

21. Investigation of Frame-Dragging-Like Signals Close to Rotating Superconductors

Dr Martin Tajmar (Austrian Research Centers)

28/08/2007, 15:30

The search for frame dragging around massive rotating objects such as the Earth is an important test for general relativity and is actively pursued with the LAGEOS and Gravity Probe-B satellites. Within the classical framework, frame dragging is independent of the state (normal or coherent) of the test mass. This was recently challenged by proposing that a large frame-dragging field...

32. Towards a New Paradigm: Relativity in Configuration Space

Prof. Matej Pavsic (Josef Stefan Institute, Ljubljana)

28/08/2007, 16:15

A generalization of the theory of relativity is considered in which spacetime $M_4$ is replaced by the configuration space ${\cal C}$ associated with a given physical system. In particular, for a system of point particles we assume that its dynamical behavior is determined by the minimal length action in ${\cal C}$. In other words, the system is considered as a point that traces a...

22. Gravitational Limitations on space and time measurements and fundamental loss of coherence in General Relativity

Prof. Jorge Pullin (Louisiana State University)

29/08/2007, 09:00

There are gravitational limitations on how accurately one can measure space and time. As a consequence of these limitations, when one formulates quantum mechanics and quantum field theory in terms of real measuring rods and clocks the resulting theory is not unitary. This has implications for the black hole information puzzle and may in a not too distant future lead to testable experiments.

30. Emergent spacetime

Prof. Matt Visser

29/08/2007, 09:45

There is a possibility that spacetime itself is ultimately an emergent phenomenon, a "low-energy long-distance approximation", similar to the way in which fluid mechanics is the near-universal low- energy long-distance approximation to quantum molecular dynamics. If so, then direct attempts to quantize spacetime are misguided --- at least as far as fundamental physics is concerned.