Albert Einstein finally hit on the core idea underlying his famous theory of relativity one night after months of intense mathematical exercises. He had given himself a break from the work and let his imagination wander about the concepts of space and time. Various images that came to mind prompted him to try a thought experiment: If two bolts of lightning struck the front and back of a moving train at the same time, would an observer standing beside the track and an observer standing on the moving train see the strikes as simultaneous? The answer, in short, was no. The floodgates in Einsteins mind opened, and he laid down an ingenious description of the universe. With his sudden insight, Einstein turned our conceptions of time and space inside out.