Just wanted to hijack and say about mechanics vs. theoretical physics... that yeah, we can research steam-based mechanics more easily than quantum physics, but it's more obvious if you don't do your research fully. Given an appropriate setting (i.e., The Future, or a more advanced civilization), you can make up stuff and, provided you have enough grasp of the basics and a way with words, make it work. You can't really make up stuff with steampunk, you have to really figure out what you're talking about.

Which isn't to say steampunk isn't just as awesome ;) GUH. I love it.