The devil (or the good god) is in the detail
Today I realized that no matter how much you dig into a topic, there are always interesting things to learn and surprises to be had.
The concrete example is this: My first research project ever, a 2-month research internship at Uppsala University, was to analyze spectropolarimetric data of a star and infer properties of its magnetic field. I had little time to dig into details. So I learned about polarization a bit, I learned about stellar spectra a bit, I learned about stars a bit, and about topographic imaging. This was a lot of fun and motivated me to continue into astronomy, eventually taking up a PhD with the same supervisor at Uppsala University.
During the PhD, I worked more on spectropolarimetry. I also helped build a spectropolarimeter for the CRIRES+ instrument. I got to learn about the instrument itself, how we can get the polarized spectra from the stellar light. I dug into the realms of instrument electronics, hardware, the optics, the control software, the mechanics. In the end, I thought I had a good idea how things work in the instrument (I was a bit wrong).
Now, during my postdoc, we commission the instrument at last at the telescope! It’s time to test many things I had little idea about: the way the observation blocks are handled, observing templates, FITS header management, and quality control. It was also time to test the data reduction pipeline on on spectropolarimetric observations. I got to dig into the equations of Stokes parameter demodulation, and see all the kinks and clever details in the software implementation.
The bottom line is: I found interesting things, strokes of genius, clever implementations, and also seemingly absurd things at all levels. I would actually not mind keep going deeper into the instrument business, e.g learning more about the manufacturing of polarization gratings (which are still a mystery to me), or into the pipeline-writing business.