Many people think time travel is absolutely ludicrous, but one has to consider what kind of time travel they are referring to. To travel back in time is ludicrous, because if this were ever to become possible, there would have been discovered evidence of time travelers from the future that came to our time. Time travel according to Einstein's theory of Relativity, however, is not only plausible, but true. According to Einstein, as one increases the speed at which they travel, the rate of change of time is less for them than it is for an outside observer. Based on this idea, one can travel in time by going at incredibly high speeds. By traveling at high speeds, a person will age slower than an outside observer, showing the person traveling so quickly will have, in essence, time traveled forward. So time travel backward will, most likely, never exist, but time travel forward, if great enough speeds are attainable, is fairly simple to accomplish.