Albert Einstein was arguably the most influential physicist of the 20th century who is synonymous with genius. Learn more about him and other influential people, authors, scientists, and more from around the world!
SPECIAL RELATIVITY THOUGHT EXPERIMENT Einstein used gedankenexperimente (thought experiments) to help him devise some of his theories. In one of these thought experiments, he imagined how two people, one on a fast train and the other stationary on a platform, would observe a flash of light. Einstein postulated the speed of light is the same for all observers in all directions. In order for this to be true, other things like time and length, needed to change. His theory of special relativity put forward the idea that time and distance is not the same for two observers if they are both moving at a different relative speed.