The medium through which light travels is called the electromagnetic field. Light is an electromagnetic wave consisting of oscillating electric and magnetic fields, and these fields propagate through space. However, it is important to note that light does not require a physical medium to travel through, unlike sound, which needs a medium like air, water, or solids to propagate.
In the early days of scientific understanding, there was a concept known as the "luminiferous aether," which was proposed as the medium through which light waves propagated. However, experiments such as the Michelson-Morley experiment in the late 19th century failed to detect any evidence of such an aether, leading to the abandonment of the idea.
The development of electromagnetic theory by James Clerk Maxwell in the 19th century provided a mathematical framework that unified the understanding of electricity, magnetism, and light. Maxwell's equations describe how electric and magnetic fields interact and propagate through space. These equations demonstrate that electromagnetic waves, including light, can exist and propagate even in the absence of a physical medium.
Based on experimental evidence and theoretical frameworks like Maxwell's equations, we understand that space itself is not made up of light or other forms of electromagnetic radiation. Instead, space is considered a vacuum, devoid of any substantial matter or medium. Light can travel through this vacuum because it is an intrinsic property of electromagnetic waves to propagate through empty space.
In summary, light travels through the electromagnetic field, but it does not require a physical medium. Space itself is not composed of light or electromagnetic radiation but acts as a medium through which light can propagate.