The most important conclusion to be drawn from the Michelson-Morley experiment is that b) light does not travel through a luminiferous ether.
This groundbreaking experiment, conducted in 1887, aimed to detect the presence of a hypothetical medium called the luminiferous ether, which was once thought to be necessary for the propagation of light waves. The experiment used an interferometer to compare the speed of light in perpendicular directions, expecting to find a difference due to Earth’s motion through the ether.
However, the results were null, showing no significant difference in light’s speed in either direction. This unexpected outcome challenged the existing ether theory and ultimately led to the development of Einstein’s theory of relativity, which posits that the speed of light is constant in a vacuum regardless of the observer’s motion. The Michelson-Morley experiment is thus a pivotal moment in physics, illustrating that light does not require a medium to travel, fundamentally altering our understanding of space and time.