Zenith Grant Awardee

Sabine Hossenfelder

Frankfurt Institute for Advanced Studies

Project Title

Spacetime Defects

Project Summary

Quantum gravity is necessary to understand what space and time fundamentally are. One of the central questions in the research area is whether this fundamental structure is discrete, ie whether there are `atoms\' of space-time. The aim of this project is to identify the most promising experimental tests for space-time discreteness. The tests subject of study here rest on the realization that if space-time is discrete, then its discrete structure should have imperfections much like crystals have imperfections. While directly testing the discreteness is beyond our experimental possibilities, detecting the defects may be possible because the defects can affect how particles travel through space-time. To make reliable predictions, it is necessary to develop a theory for space-time defects from which the observable consequences can be derived. The purpose of the here proposed project is to develop such a theory and investigate the possibility to experimentally test it.

Technical Abstract

The purpose of this project is to fully develop a phenomenological model for space-time defects and, by this, to identify the most promising experiments to search for fundamental space-time discreteness. Space-time defects come in two different types, local and non-local. Such defects represent deviations from the smooth background geometry in our current theories, and they should generically exist in approaches to quantum gravity that rely on discretizations. The presence of both local and non-local defects must be consistently incorporated into a modification of quantum field theory and general relativity. In a previous work, the basis for such a model of space-time defects has been obtained, but so far only in flat space. In this project, I want to further develop the model so that it can be used in general backgrounds. This will allow one to then analyze cosmological observables. These observables can either contain evidence for space-time discreteness or they will deliver constraints on the density of defects.