I've felt similarly, but I found that part of the problem was that I was seeking acceptance and participation from my friends, even though I was occupying myself with increasingly specific and esoteric things. Part of the solution was just caring less what other people think, and mentioning to them only the pretty/nifty/cool/engaging things that I work on, not the theoretical stuff.
Another good tip is that, with some time and effort, you can largely shape the kind of new friends you meet, especially today with the web. You could organise some informal gettogethers, interest groups, lectures, etc. Providing free beer helps a lot. Leverage your workplace, your school, your local watering hole. Hunt for people who are doing the same things you do. Blog about what you do, so others can find it. These days, you can automate a lot of this just by setting up search feeds on Google, Twitter, etc. Even on something as noisy as Twitter, there's someone talking about fluid dynamics, linguistics, philosophy, etc. Find them, see what places they link to, and join their communities so you can find out where they hang out in real life. The trick is to not treat the online world as a separate place where the "cool people hang out", but simply the medium through which "cool people hook up". Most of the people you want to hang out with are in the same boat as you: bored, alone and online.
The fact is that you are less likely to meet someone truly interested in your pursuits than just regular 'nice people'. Accept this, but make sure you are ready to encounter these special people and show them, very quickly, that you are a smart person worth getting to know and worth having in depth conversations with.
Also, though the hacker lifestyle has its perks, it never hurts to expand your interests to include more outdoor activities. Often you can be as intellectual and nerdy about those as you want, without suffering the nerd penalty.
As for correcting people on urban legends: people don't like being told they're wrong and many people enjoy urban legends for the drama and excitement, because it gives them a story to tell. Often they don't really care if it's true or not.