Final answer:
Light can travel through a vacuum because it is an electromagnetic wave that does not require a medium, while sound cannot travel through a vacuum because it is a mechanical wave that requires a medium.
Step-by-step explanation:
The reason light can travel through a vacuum, such as outer space, but sound cannot is that light is an electromagnetic wave, which does not require a medium to transfer energy. In contrast, sound is a mechanical wave that needs a medium, like air, water, or solids, to propagate because it is essentially a series of pressure disturbances. To illustrate, think of light as capable of self-propagation through its oscillating electric and magnetic fields, while sound waves require a material substance through which the molecules can vibrate and pass the wave along.