Here's why:

* Refraction: Light bends when it passes from one medium to another because the speed of light changes in different materials.

* Vacuum: A vacuum is the absence of matter. Since there's nothing to interact with, light travels at its fastest speed, the speed of light in a vacuum (approximately 299,792,458 meters per second).

* Other Materials: In all other materials, light interacts with the atoms and molecules, slowing it down. The more dense the material, the more the light is slowed and the more it bends.

Therefore, light experiences no bending in a vacuum because its speed remains constant.