Contrary to the old warning that time waits for no one, time slows down when you are on the move. It also slows down more as you move faster, which means astronauts some day may survive so long in space that they would return to an Earth of the distant future. If you could move at the speed of light, your time would stand still, if you could move faster than light, your time would move backward.
Although no form of matter yet discovered, moves as fast as or faster than light, scientific experiments has already confirmed that accelerated motion causes a travelers time to be stretched. Albert Einstein predicted this in 1905, when he introduced the concept of relative time as part of his Special Theory of Relativity. A search is now under way to confirm the suspected existence of particles of matter that move at a speed greater than light. And therefore, might serve as our passports to the past. An obsession with time--saving, gaming, wasting, losing and mastering it-- seems to have been a part of humanity for as long as human have existed. Humanity also has been obsessed with trying to capture the meaning of time. Einstein used a definition of time for experimental purposes, as that which is measured by a clock. Thus time and times relativity are measurable by any hour glass, alarm clock, or atomic clock that can measure a billionth of a second.
