New time for exercises from MONDAY 23/9!

Hi everyone! Just a quick note to clarify the program for the upcoming two exercise sessions.
On Friday 20/9 (10:15-12:00, Kristian Birkelands Auditorium) we'll finish up the discussion of Problem 9 about propagators. We'll also start tackling Problem Set 4, as far as we get.
On Monday 23/9 (09:15-12:00, Kjemi Auditorium 3) we'll continue where we left off. Since we got an extra hour (woohoo!), we will also discuss some new exercises (working out a few things that the book leaves up to the reader). I realize there isn't much time to prepare them in detail, but try to have a look at them so you at least understand the question and have a good idea for how to get started.

As the lectures will have covered the quantization of the Dirac field by then, it's a great opportunity to reflect on the course content of the past few weeks and read up in the book. It is impossible that this doesn't raise a single question (both at the conceptual level and regarding technical details of calculations/derivations), so we'll have a Q&A round on Monday.
By then, come up with at least one question so that we can do a complete round of class!