Your question touches on the nature of light and how it behaves in different environments. While it is true that many waves, such as sound waves or water waves, require a medium to propagate, light is a bit different.
Light is an electromagnetic wave, and it doesn't require a medium to travel through. This property was one of the fundamental discoveries in the field of electromagnetism, credited to James Clerk Maxwell in the 19th century. Maxwell's equations mathematically described the behavior of electric and magnetic fields, leading to the conclusion that light is an electromagnetic wave.
In a vacuum, such as outer space, there is no air or other matter to act as a medium for light to travel through. Yet, light can still propagate because it is not dependent on a physical medium like other types of waves. Instead, light consists of oscillating electric and magnetic fields that can travel through empty space.
The wave-like behavior of light arises from the interaction of these electric and magnetic fields, as described by Maxwell's equations. These fields generate each other and can sustain each other's propagation, allowing light to travel as an electromagnetic wave even in a vacuum.
It's important to note that while light can travel through a vacuum, its speed can be affected by the presence of matter. When light passes through different materials, such as air, water, or glass, its speed and direction can change due to interactions with the atoms or molecules of the medium. This phenomenon is known as refraction. However, in a vacuum, light travels at its maximum speed, often referred to as the speed of light in a vacuum, which is approximately 299,792,458 meters per second (or about 186,282 miles per second).