Most people imagine time as a constant. Physicist Albert Einstein illustrated that time is an illusion that it is relative which it can differ for different observers depending on the speed through space. To Einstein, time is a fourth dimension and space is described as a three-dimensional arena, which provides a traveler with coordinates such as length, height and width showing location. Time provides another coordinate direction although conventionally, it only moves forward. Time travel is transporting between different points in time. It has been a popular theme for science fiction for decades. From the science fiction movies "Doctor Who" to "Star Trek" to "Back to the Future" has seen humans get in a vehicle of some kind and arrive in the past or future, ready to catch on new adventures. The reality still is more muddled. Not all scientists think that time travel is possible. Some even say that an attempt would be fatal to any human who chooses to take on it. Albert Einstein is one of the greatest scientists in the 20th century who developed the theory named Special Relativity. The ideas of Special Relativity are very hard to imagine because they aren 't those things that we experience in everyday life, but scientists have already confirmed them. The Special Relativity theory says that space and time are really the aspects of one thing which is the space-time. There 's a speed range of 300,000 kilometers per second (or 186,000 miles per second) for