Gravitational waves after Easter

After Easter we will start directly with the discussion of gravitational waves. I will unfortunately not be able to make it for the first lecture, on April 22, so I just uploaded a lecture video instead. There are also 'slides' in case you want to skip the video or recap.

NB: On Wednesday, April 23, I will continue by assuming that you have all watched these lectures! (But of course there will still be opportunities for questions at the beginning, as usual)