In the physical sciences, a horizon is a defined boundary of observation or causality.
The concept of a "horizon" serves as both a literal boundary and a powerful metaphor across science, philosophy, and strategic planning. Physically, it is the line where the earth and sky appear to meet, but intellectually, it represents the limit of what we can currently see, know, or achieve. The Scientific Horizon: Physical and Cosmological Limits
: A horizon is seen as a paradoxical limit; when you look directly at it, it ceases to be the horizon and becomes part of your view, always receding as you move. The Strategic Horizon: Planning and Scanning