The mere asking of these questions stretches our minds, and the continual search for answers provides useful insights along the way. The concept of time is central to all the world's religions.
Most cultures have a grammar with past and future tenses.
Most societies have some kind of demarcation such as seconds and minutes, and yesterday and tomorrow. The study of time became scientific during the time of Galileo and Newton, but a comprehensive explanation was given in the twentieth century by Einstein, who declared, in effect, time is simply what a clock reads. For physicists, the question as to whether or not time travel is possible is a most important one, if only to discover whether we live in a causal or acausal universe. Thanks to Einstein we may at least approach the notion of Time Travel. As Albert Einstein showed back in 1905 with his special theory of relativity, time slows down for objects moving close to the speed of light, at least from the viewpoint of a stationary observer.