# Johannes Oude Groeniger: How to choose your gauge

**Time: **
Fri 2022-04-29 15.15 - 16.15

**Location: **
KTH, 3721 and Zoom (meeting ID: 68578498723)

**Participating: **
Johannes Oude Groeniger (KTH)

**Abstract**

A key feature of Einstein's theory of general relativity is its invariance under coordinate transformations. This doesn't rhyme well with the idea of an evolving system or an initial value problem, let alone proving existence and uniqueness of solutions to such a system.

In order to do so, one has to "break the gauge freedom of the equations'', i.e. one has to choose a gauge. What does this mean? And how do you do it?