I received an email today, with a subject, "Do you use two-by-two matrices when you write papers?"
It seems like a rather strange question, and it comes as part of an email soliciting papers for a new open access journal that I haven't heard of. They are running a special issue on "Physics based on two-by-two matrices". Now, these objects crop up all over the place; in rotations, for example. In any two-level mixing problem. Or they can be used to describe quantum mechanical particles with an intrinsic "spin" angular momentum, such as protons, neutrons and electrons, so yes - very applicable to my work in nuclear physics.
The question sounds so generic. "Do you use numbers?" might be as apt, yet it is also so specific - particularly concerning itself with matrices of a particular size. I can't help but think that it is a rather contrived way to promote interest in a new journal that charges a minimum of 500CHF (about £350) to authors to publish each paper. Perhaps I am being unduly sceptical and when the special issue comes out, I will discover that there are a slew of article showing profound links between diverse areas of physics. That is, if I even notice the issue be released amongst the huge number of very general new journals out there.