Any copyeditor who tells you he or she doesn't love the learning part of the job is probably not a great copyeditor. Though my own university-level science background was more along the lines of rocks for jocks and math for divas, I'm still more than conversant with the major topics in various scientific disciplines. What I don't know, I love finding out.
Always an armchair scientist and self-described geek, I will usually drop everything (thanks, gravity!) to work on a book of popular science. However, it should be known that I can't stop making "hadron" jokes to myself as I work on books on particle physics or shouting, "Science!" like Thomas Dolby. I'd like to think it's part of my charm.