# Flat Earth And Theorema Egregium You don't need physics to show that the earth is round. Theorema Egregium is literally what every math undergrad learns. It says that the Gaussian curvature of a surface is intrinsic. > The theorem says that Gaussian curvature can be determined entirely > by measuring angles, distances and their rates on a surface, > without reference to the particular manner in which the surface > is embedded in the ambient 3-dimensional Euclidean space. You can determine the Gaussian curvature of the earth without leaving the surface. And you know what? The value is not 0. In other words, it can't be flat. Despite of that, I think being a flat earther is a good thing though. Since ANYTHING GOES! If we modify the theory, we could apply it to our flat SOLAR SYSTEM and flat GALAXY. It might provide better explanations than the current theory. I just don't believe in flat EARTH.