[@sntabe] Ah, sorry, I must've missed that. I'm going to say no calculus, thereby no Newtonian mechanics yet. Though, if you want, you could have your character working such problems out, as he's a pretty smart dude. The earliest lenses were a 12th century invention according to google, so Zeke is cutting edge, but not in the realm of implausible. Microscopes, however, were a 17th century thing, so no cell theory. Heliocentrism is fine. It's really the church's fault it took so long to catch on. Hope that answers your questions.

[@ReusableSword][@Force and Fury] Well, if you guys don't mind, he can jump in. Just make a profile, Sword, and I'll take a look.