In contrast, light waves can travel through a vacuum, and do not require a medium. In empty space, the wave does not dissipate (grow smaller) no matter how far it travels, because the wave is not interacting with anything else. ... Therefore, it fills a space given approximately by the surface area of a sphere.

Why does light fade over distance?

Notice that as the distance increases, the light must spread out over a larger surface and the surface brightness decreases in accordance with a "one over r squared" relationship. The decrease goes as r squared because the area over which the light is spread is proportional to the distance squared.

How does light disappear?

The fields in the photon, being exactly the same type of fields in the atom, interact with the atom and the photon "disappears" as the energy that it was made of is transferred by these fields into the atom.