It's a naive question, but I'm pretty sure my professor said that space-time is locally flat (and I'm pretty sure that the volume of my room counts as "locally"). That said, I would expect falling objects to follow straight trajectories, but that's obviously not the general case. I thought this could be because straight lines in space-time can be curved when seen in space, but it doesn't seem possible when I try to make some calculations. Why are geodesics parabolae on the surface of earth? Where am I getting something wrong? Thanks!