The concept that light requires a medium to travel through space was proposed by ancient scientists, known as the "luminiferous aether" theory. However, it was ultimately debunked by the famous Michelson-Morley experiment in the late 19th century, which provided evidence against the existence of such an aether.
The Michelson-Morley experiment was designed to detect the motion of the Earth through the hypothetical aether medium by measuring the speed of light in different directions. The experiment involved splitting a beam of light and directing it along two perpendicular paths, then recombining the beams to observe any interference patterns. If there were an aether, it was expected that the speed of light would be faster in the direction of the Earth's motion through the aether and slower in the perpendicular direction.
However, the results of the Michelson-Morley experiment showed no significant difference in the measured speed of light along the different directions. This suggested that the speed of light is constant and independent of the motion of the observer or the hypothetical medium it travels through.
The absence of any detectable effects in the Michelson-Morley experiment led to the development of Albert Einstein's theory of special relativity, which revolutionized our understanding of space, time, and the behavior of light. According to special relativity, the speed of light in a vacuum is always constant and is the same for all observers, regardless of their motion relative to the source of light or any medium it may pass through.
Since the Michelson-Morley experiment, numerous other experiments and observations have consistently confirmed the principles of special relativity and the constancy of the speed of light. These include measurements of the speed of light in various media, the behavior of particles traveling at high speeds, and the observation of cosmic phenomena.
In conclusion, the Michelson-Morley experiment and subsequent scientific investigations have provided strong evidence that light does not require a medium to travel through space and that it can propagate through a vacuum. This understanding is a fundamental principle of modern physics and has been extensively validated through experimental and observational data.