Speed of light
A consequence of this fact that the speed of light is the same for all observers, is that nothing can go faster than the speed of light. Another consequence is that for objects that have mass, no matter how much energy is used to increase the speed of an object, it will get closer and closer, but it will never reach the speed of light. These ideas were discovered in the early 1900s by Albert Einstein, whose work completely changed our understanding of light.