Surfaces

 

Blue Horizon

Beyond the blue horizon
Waits a beautiful day
Goodbye to things that bore me
Joy is waiting for me
I see a new horizon
My life has only begun
Beyond the blue horizon lies a rising sun

The horizon is why Pythagoras Theorem applies Locally by not Globally

There are three kinds of surfaces. 1) Spherical, 2) Flat (Euclidean) and 3) Hyperbolic. While it seems like we live on a flat Earth, the existence of the horizon is actually one of the proofs that the surface of the Earth is actually a sphere, not flat. An observer can perceive 50% of any object that is between the observer and the horizon. An observer can not perceive the object at all if it does not extend above the horizon. However the observer can only perceive 50% of the portion of any object that extends above the horizon. That is why the mast of a sailing ship on the horizon is visible before the rest of the ship, because at that point  the mast extends above the horizon, but the rest of the ship does not. The horizon is defined by the radius of the spherical surface. If the sphere is large enough, then most objects which are perceived will be between the observer and the horizon. But that does not mean that the horizon does not exist, just that it is not always perceived. A Flat surface is thus only the limit of the spherical domain, not a domain itself. The surface will have a curvature defined by the major and minor axes, a and b, of the equations describing the eccentricity of the surface. If a and b are both less than infinity, then a spherical surface is described, and the eccentricity is less than 1. If a and b are both infinite, then a hyperbolic surface is described, and the eccentricity is greater than 1. A flat surface is thus only the boundary between these two conditions where the eccentricity is exactly equal to 1.

For any hyperbolic surface, regardless of the curvature, only 5/6 or 1/6 of an object will be perceived, depending on which side of the hyperbolic surface is being perceived by an observer. That is because a hyperbola has two solutions, one which is the opposite sign of the other. But the solutions are similar to the spherical solution until the numbers involved are very large: e.g. 2/3 the size of the universe or 5/6 the speed of light. Thus could it  also be said that the universe is flat locally, but hyperbolic universally.