[Acheron]

There's nothing at all wrong with having standards. Being with someone that you don't like is miserable, and in any case having no standards at all is a sign of desperation. But at the moment you're being too prescriptive. Chemistry beats type, every time. Try dating around a little. You've said that there are attractive girls that are interested in you, so it shouldn't be too difficult. Even if they aren't as scientific as you, you might be pleasantly surprised. And dating isn't exclusive, so you can still try to score with your sciencey types.

EDIT: OK, just saw your last post. If you just want them not to fall asleep during your science talk, that makes your job even easier. No matter the field, girls love to hear their guy talk about something he's passionate about, even if they aren't so interested in it. I've occasionally talked politics to girls that weren't political, and they've been interested just because it was something I was interested in. See, girls don't like to be the centre of your existence. If you have something going on that's more interesting than she is (in your case, maths and science) it actually makes her more interested in you. Your ex is pretty normal in that respect.