I am a programmer and my colleague is a scientist, we are similar ages and at the same seniority. Neither of us have a background in economics, though I have studied some economics out of interest.
One day an economist was visiting our department, and the Phillips Economic Machine came up. My colleague started explaining to me what it was, and I said "Oh yes, they're awesome, there's one in the Science Museum in London...", and the conversation carried on happily.
Later the same day, with a different economist, the subject of Nassim Taleb came up, and my colleague turned to me and started to explain to that Nassim Taleb wrote a book called Black Swan, about unusual events... I rolled my eyes and said "I know who Nassim Taleb is", before the conversation continued. My colleague perceived my eye-rolling as rude, and said so.
I believe my colleague was trying to be helpful, and I shouldn't have rolled my eyes. However, I was annoyed by my colleague's assumption that I needed the explanation, about a really popular author, in a field in which neither of us is an expert, when I had demonstrated that I already knew about a more obscure topic in popular economics a few hours earlier.
Unfortunately, explaining happens to me quite a bit, and I usually ignore it, but get irritated internally. Sometimes after I've given a talk about a specialist programming topic, people will come up and start telling me about much more introductory topics in the same field, unsolicited.
What's a polite, gentle way to stop people explaining to you things that you already know? I'm not talking about situations where the person has no context about you: I'm talking about situations where you've already shown that you have knowledge of the area, and the person continues to assume you know less than they do.
Perhaps I should just allow the explaining, especially with strangers. But I would like to find a polite, non-hurtful solution, because (i) it's boring to have things explained to me that I already know, and (ii) it feels strangely invalidating, like the other person hasn't really absorbed who I am.
Thanks for any advice.