This blog contains thoughts and observations on a wide range of physics related topics that I find interesting and which I believe are worthwhile sharing. My goal is to create one new entry every month. Some of the entries are rather opinionated and I'm always happy to discuss them in more depth. Feel free to send me an email for further discussion, and of course also if you find any mistakes: stefan.kehrein@theorie.physik.uni-goettingen.de