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My old toy train is a perfect way of illustrating Einstein's profound question.
我以前的玩具火车 最适合用来解释爱因斯坦的深奥问题
of what the fixed speed of light meant for the universe.
光速恒定对宇宙的意义
Einstein started with a simple question:
爱因斯坦先从一个简单的问题开始
How fast is something like this little train moving?
这列小火车的行进速度有多快
Well,this is the 1950s and toy trains weren't all that good.
当时是1950年代 玩具火车的品质并不怎么理想
So let's say it's traveling at about one mile per hour.
就假设行进速度大约每小时1600米吧
But change way you look at it from. You get a different answer.
但若改变观察点 就会有不同的答案
The earth spins on its axes at around 1,000 miles per hour.
地球以大约1600公里的时速绕着地轴旋转
So,seen from up here,my train is actually traveling much faster.
所以若从这里看 这列火车的速度就快得很多
Of course,the earth as a whole is orbiting the sun at 67,000 miles per hour.
当然整体而言 地球绕着太阳旋转 且时速为108000公里
And even the sun isn't stationary. It is orbiting the center of the milky way.
就连太阳也并非静止 而是绕着银河系的中心旋转
And the Milky Way is moving through space,too.
而银河系也在太空中旋转
So how fast is the train really moving?
那么火车的行进速度究竟有多快？
Well,it all depends on way you see it from.
答案完全取决于从哪里观察
It could be 1 mile per hour,1,000 miles per hour,60,000 miles per hour.Or many times faster.
可能是每小时16公里 每小时16000米 每小时10800公里 甚至快好几倍
