公共英語PETS-2精品閱讀2

　　Time travel is clearly a trickier proposition than space travel, though. Put simply, Einstein's idea was that every object in the universe has it's own “time”, and these vary as objects move. The faster an object moves, the slower its time is, compared to the time of a slower moving object. The extreme situation would be if an object could move as fast as the speed of light, its time would be completely halted. But whatever an object--or person's--time is, it's only evident in contrast to other objects. In other words, it's all relatives.

　　與太空旅行相比,時間旅行很顯然是一個更為復雜的命題。簡而言之,愛因斯坦的觀點就是,宇宙中每一物體都有其自身的“時間”,并隨其運動的不同而不同。物體運動越快,其時間越慢(與運動較慢的物體相比而言)。最極端的假設是,如果一個物體運動達到光速,那么其時間就會完全停止。但無論一個物體或者一個人的時間為何,它只能參照其它物體才能得以體現。換句話說,萬物皆相對。