Berlin 2012 – scientific programme

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PV: Plenarvorträge

PV 23: PV XXIII

PV 23.1: Evening Talk

Thursday, March 29, 2012, 18:00–18:45, H 0105

Lise-Meitner-Lecture: More than meets the eye: Probing the Planckian structure of spacetime — •Renate Loll — Institute for Theoretical Physics, Utrecht University, The Netherlands

Time and Space are at once ubiquitous and mysterious. We are immersed in space and experience the flow of time, but what is their essence and origin? Our view of space and time has undergone radical changes since Newton's days. In Relativity, they form inseparable parts of a four-dimensional ``spacetime", which moreover can bend and move, encoding the gravitational interactions of matter and energy.

Beyond the validity of Einstein's classical theory, we expect further insights into the nature of spacetime from quantum gravity, the eagerly searched-for unification of relativity and quantum theory: what governs the quantum dynamics of spacetime on ultrashort, Planckian scales? How can it explain the observed macroscopic structure of spacetime? Are space, time, causality and dimensionality still meaningful notions at the Planck scale, or merely emergent properties of a dynamical ensemble of more fundamental microscopic `building blocks'?

I will report on recent, unprecedented progress in a new formulation of quantum gravity, a concrete (and computable!) realization in terms of ``Causal Dynamical Triangulations" of a Feynman path integral. Intriguingly, it has been possible to extract physical properties of this quantum superposition of spacetimes with the help of numerical ``experiments". They confirm the nonclassical and counter-intuitive nature of spacetime at the Planck scale - including a bizarre behaviour of ``dimensions" - and the emergence of classicality on large scales.