Gravitational lensing provides an important probe of the background geometry.

In this talk, I discuss light propagation on non-Lorentzian backgrounds which

arise in two different contexts. Firstly, we consider optical geometry, which

is a formalism in 3-space for light propagation in Lorentzian spacetimes:

static spacetimes give rise to Riemannian optical geometry and stationary

spacetimes have a Finslerian optical geometry of Randers type. I will

review basic results as well as recent work using the Gauss-Bonnet theorem

and curve-shortening flow. In particular, the first isoperimetric inequality

in this context will be presented. Secondly, we consider a general formalism

for arbitrary tensorial (not necessarily metric) spacetime kinematics and

outline how gravitational dynamics can be derived such that the theory is

causal by construction. This new geometrodynamical approach is called

constructive gravity. I will briefly describe first results for light

propagation on a non-metric (specifically, area metric) background that

allows birefringence to occur and yields deviations from the standard

Etherington distance duality relation which can be probed observationally.

# Optical Geometry and Constructive Gravity

Event type

Event date

Venue

Venue Maths. Dept. Room Sousa Pinto

Ends on

Speaker

Marcus Werner (IPMU, Japan)