Sesson 2: Reflection & Visibility

Key Idea

Vision is a result of light interacting with matter. The process involves a specific sequence: light travels from a source, hits an object, and then bounces off. This bouncing of light is called reflection.

However, reflection alone is not enough for vision. For an animal to actually see the object, that reflected light must travel away from the object and physically enter the animal's eye. If the reflected light goes in a different direction and misses the eye, the object will not be seen.

Key Idea

Scientific models of vision trace a continuous path of light. This path has three key components that must happen in order:

1. Light travels from the source to the object.
2. Light reflects off the object.
3. The reflected light travels from the object to the eye.

This entire journey must be completed for vision to occur. If the path is broken at any point, the visual system fails to detect the object.

Key Idea

Because light travels in straight lines, it can be easily blocked. An object that stands between the light source and the eye acts as an obstacle.

If an obstacle interrupts the path of light—either preventing light from hitting the object or preventing reflected light from reaching the eye—the object becomes invisible to the observer. An object's visibility is entirely dependent on an clear, uninterrupted line of sight.