Will Time Ever End?

It’s an old story but one worth repeating.  A man rushed into the railroad station and breathlessly asked, “When does the 8:01 leave?” “At 8:01,” replied the railroad clerk, not bothering to look up from his newspaper.  “Well,” said the man, “it’s only 7:55 by my watch,” but, somewhat worried, added, “it’s 8:04 by the station clock.  Which one should I go by?”  Sardonically the railroad clerk replied, “You can go by any clock you wish, but you won’t be going on the 8:01 because it has already left.”