A man goes back in time, and kills his grandfather before the grandmother can meet his grandmother. This means that one of the man’s parents will not have been born, and the man in turn, will not have been born. This would mean that he could not have travelled back in time after all, which means the grandfather would still be alive, and the traveller would have been conceived allowing him to travel back in time and kill his grandfather.
ANSWER: The moment the time traveller changes something in the past, a parallel universe splits. This is supported by quantum mechanics.
A crocodile steals a son from his father, and promises to return the child if the father can correctly guess what the crocodile will do. What happens if the father guesses that the child will not be returned to him?
ANSWER: There is no solution. If the crocodile keeps the child, he violates his rule, as the father predicted corretctly. If the crocodile returns the child, he still violates his rule as the father’s prediction was wrong.
2010-09-03 13:00 编辑：kuaileyingyu