So what's the problem?
这是怎么回事?
Anyone can understand that speed is relative to your perspective.
大家都知道 速度多少是相对于观察点的
But when you remember that unlike the speed of the toy train.
不同于玩具火车的车速
the speed of light is fixed no matter what your perspective.
无论从任何观察点 光速始终保持恒定
then that common sense view things starts to break down.
因此一般的观点就开始瓦解
To explain why Einstein imagined a train,too.
为了解释原因 爱因斯坦也想象出一列火车
Only his was full-sized.
只不过是真实大小的
He devised a thought experiment,asking how something as simple as the lighting of a cigarette light tip.
他设计了一项思考实验 探寻像点燃打火机这么简单的事
would look to people with different points of view.
为何不同的人会看到不同的结果
He imagined a man playing with his lighter in the center of a railway car.
他想象有人在车厢中央玩打火机
being watched by two people at either end.
车厢两头各有一个人在看
Both at exactly the same distance from the lighter.
两人与打火机的距离相等
Einstein said the interesting question is not what do these people see.
爱因斯坦表示值得探究的问题 不在这两人看见了什么
But when do they see it.
而是何时看见
Because they're in the same car or moving together at the same speed.
因为他们都在同一节车厢里以相同的速度前进
the two observers see the light at exactly the same time.
两名观察的人都在同一时间看见火光