The Horizon Problem for Faster than Light Travel
Hello all, As I have mentioned in previous posts, a major hurdle for autonomous FLT travel is the horizon problem. But what is a horizon? Is it some single well-defined concept or a catch-all term for many phenomena? In this post, I present some thoughts on horizons in general relativity theory and their implications for FTL travel using warp drives. A horizon is a limit to the region that can be observed or communicated with in a space. On Earth, horizons can be used to refer to edge of what can be seen when looking out over a vast body of water like an ocean. The limit to what can be seen in this case is caused by the curvature of the Earth's surface and is a cute problem to calculate how distant the horizon appears given the height of an observer above the surface of a spherical Earth (ignoring effects of the Earth's atmosphere) that is straightforward to solve as it is embedded in a Euclidean geometry. An observer looking out to the Earth's horizon from a height h abov...