Here's why:

* 3D Space: Light travels in three-dimensional space.

* Angles: Within that space, a ray of light can be pointed in any direction, which can be defined by its angles relative to a set of axes.

* Continuous Values: Angles can take on any value within a range (typically 0 to 360 degrees or 0 to 2π radians). Since these values are continuous, there are infinitely many possible combinations of angles.

Therefore, the number of possible directions for a single ray of light is infinite.