Nontrivial small-scale structure of spacetime and consequences for particle propagation

• Applicant: Professor Dr. Frans R. Klinkhamer
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 159859086

Lorentz invariance is the cornerstone of our understanding of subatomic physics. At the same time, we know that the present theory is incomplete and that quantum gravity will change the picture dramatically, perhaps including a breakdown of Lorentz invariance at very small length scales. But there is, at present, no viable theory of quantum gravity which would predict or rule out such a breakdown. Thus, if one could experimentally detect or rule out Lorentz invariance breaking at the Planck energy scale, it would vastly enhance our understanding of space and time and aid in the search of the correct theory. Observatories such as HESS or Auger detect ultrahigh-energy particles which can probe Planck-scale physics. In fact, certain special forms of Lorentz-invariance breaking have already been ruled out by these observations. However, results such as these require a theoretical framework. Only if the theoretical framework is not purely phenomenological but based on a model of (quantum) spacetime, can the observations tell us something concrete about the structure of spacetime at the smallest length scales. The goal of the present project is to build such a framework. We want to develop simple and reliable models of spacetime at small length scales, derive their phenomenological consequences, and, by comparison with observations, learn something about the nature of space and time. To do this, we will develop theories of spacetime defects and also bring new methods to bear on loop quantum gravity.

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Hanno Sahlmann