Ask HN: What do you do and what did you study?

I'm continually impressed with the HN community. There's always some theoretical physicist who can explain the latest impossible-sounding discovery or a virologist who can explain differences between vaccine approaches. I'm sure I've only experienced the tip of the iceberg, so curious to hear from you all - what do you do and what did you study? I would love to get a sense of what fields of expertise we've all got access to!