本文作者： 21ST
ALBERT einstein’s Theory of Relativity makes us think hard about time. If time is relative like space, then can you travel through time as well? Science fiction has explored this idea throughout the 20th Century. But there are some problems with time travel. The twin paradox shows how time can be slowed down, and perhaps you can see how it could be used to travel to the future. But what about traveling back in time?