Make sure your brain is good and warmed up for this one. Here we go. There’s a limit to how much of the Universe we can observe. That’s a simple enough concept but think about what that really means. Even when we send the most powerful telescope ever made as far into space as we can, there’s a limit to what it can observe because light does actually travel–and no matter how far that telescope goes and no matter how far it can see, there will always be light that still hasn’t reached it yet. The very edge of that limit, in physical terms, is the particle horizon horizon. That’s actually a distance to a point in space that can be calculated. But when we move into the theoretical realm we can start talking about infinity in a mathematical sense rather than a physical one. But if we follow that all the way through, the boundary might actually encode the physical universe it contains as a holograph on its surface.