Bremen 2017 – wissenschaftliches Programm

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GR: Fachverband Gravitation und Relativitätstheorie

GR 13: Grundlegende Probleme und allgemeiner Formalismus

GR 13.1: Hauptvortrag

Donnerstag, 16. März 2017, 14:00–14:40, SFG 0140

Quantum matter determines the underlying gravity theory — •Frederic P. Schuller — Department of Physics, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstr. 7, 91058 Erlangen

How much choice does one have in postulating gravitational dynamics? Virtually none, if one has already decided on quantizable equations of motion for all matter fields that populate the spacetime.

The mechanism is quite simple. Geometry and matter must share the same initial data surfaces, in order to allow for a common evolution. But this inevitably injects the principal polynomial of the matter dynamics into the constraint algebra of viable dynamics for the geometry. And since the constraint algebra can then be written as a linear functional differential equation for the gravitational Lagrangian, the latter can be determined constructively. In fact, the gravitational Lagrangian is uniquely determined, up to constants of integration.

Finding the gravitational dynamics that support given matter field equations thus amounts to no more, and no less, than solving a linear system of differential equations. The technicalities behind this assertion are subtle, but utterly physical. Interestingly, there is no theoretical constraint whatsoever that restricts one to a metric background, which opens up unexpected avenues for the construction of modified matter theories on refined background geometries.

We will close by demonstrating how the mechanism works in practice and point out a type of physical questions that was previously inaccessible, but can now be addressed and answered.