I don't know what might be considered "normal" for an adult special interest, but the intensity of my "trivia gluttony", as I call it, doesn't ever seem to diminish.
I had a couple of really important tasks to get done today [looks at the time, erm, I mean yesterday], but I did neither of them because I've been half asleep since waking up very late. I had been up until the early hours ploughing through the Wikipedia pages for every military aircraft flown by Japan in WWII (again!) Another time it might be the details of every single British railway disaster (again!) This will, of course, include multiple long, winding tangents - the engine in that plane, the history of the company that made the engine for the plane, the biography of the head designer of the company that designed the engine for the plane....
I'll go to bed when I finish this page. Oh dammit. Well, I'll go to bed at the end of the fighter planes section, then. Oh dammit. I'll just finish reading this one, but I mustn't click on any of its links. Oh dammit...
The most bizarre part to me is that I have absolutely no idea why these things fascinate me so much. I abhor war and violence and hate to see them glorified, so why is military hardware so fascinating to me? Who else do I know who cares about a boiler explosion in the nineteenth century? Why do I read the same facts over and over again, many of which I committed to memory already as a child? What am I going to use these facts for once I have committed them to memory? Why can't I ever seem to apply these research skills to something more beneficial?
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When you are fighting an invisible monster, first throw a bucket of paint over it.