Memes

You just discovered the field of calculus! If you look closely enough at any smooth function it looks locally linear, and the slope of that linear function is it's derivative

Not quite what's happening here, here the problem is if you consider geodesics on a sphere to be straight. In special geometry they are, for all intents and purposes, but in higher euclidian geometry they form large circles

I don't know... straight, I would assume, means that I could walk or drive a vehicle and not turn at all, ignoring any external influences like waves and currents in this case.