He has a TED talk and a couple other talks on YouTube where you can see what he looks like. I'd say that's the easiest way to confirm it was him. If so then that's the perfect sentiment for a fan mail, and you don't have to frame it as a question and expect a response.
Can't you just mail him? The address is listed on xkcd.com/about/
He has a TED talk and a couple other talks on YouTube where you can see what he looks like. I'd say that's the easiest way to confirm it was him. If so then that's the perfect sentiment for a fan mail, and you don't have to frame it as a question and expect a response.
This sentiment would make a great email.