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In our universe, when you change from a non-moving perspective to a moving one, or vice versa,
在我们的宇宙中，当你从一个静止的视角变成一个移动的视角，或者反之亦然，
that change of perspective is represented by a what's called Lorentz transformation, which is a kind of squeeze-stretch rotation of spacetime that I've mechanically implemented with this spacetime globe.
视角的改变是由一个所谓的洛伦兹变换来表示的，这是一种时空的挤压-拉伸旋转，我用这个时空球体机械地实现了这种旋转。
The spacetime globe illustrates many of the features of special relativity, like length contraction and time dilation and the twins paradox.
时空球说明了狭义相对论的许多特征，如长度收缩和时间膨胀，双生子悖论就是如此。
Which is a linguistically confusing situation that can arise in special relativity when somebody learns about time dilation - the fact that in our universe,.
双生子悖论是一种在语言上令人困惑的情况，当有人了解到时间膨胀时，狭义相对论就会出现这种情况-在我们的宇宙中，这是一个事实。
(that) things moving relative to each other each view the other's time as passing more slowly (which is called “time dilation”).
(即)相对运动的物体彼此认为对方的时间过得更慢(这被称为“时间膨胀”)。
As the paradox goes “if each person views time as passing more slowly for the other, then if my twin travels away from earth for a while and then comes back, who's actually younger when we meet again?”
正如悖论所说，“如果每个人都认为对方的时间过得更慢，那么如果我的双胞胎兄弟离开地球一段时间，然后又回来了，那么当我们再次相遇时，谁实际上更年轻呢？”
When you have a potentially confusing situation in relativity, it's really helpful to actually draw a spacetime diagram to understand what's going on.
当你在相对论中有一个潜在的令人困惑的情况时，实际绘制一张时空图来理解正在发生的事情真的是很有帮助的。
So we'll use the spacetime globe.
所以我们将使用时空球体。
The situation is this: you're sitting on earth for, let's say, 12 seconds.
情况是这样的：比方说，你在地球上呆了12秒。
Your twin travels out at a third of the speed of light for what you measure to be 6 seconds, then they turn around and come back at a third the speed of light for what you again measure to be 6 seconds.
你的双胞胎以三分之一的光速旅行，你测量的是6秒，然后他们转过身来，以三分之一的光速返回，你再次测量的是6秒。
So what does your twin think?
你的双胞胎兄弟怎么想？
Well, to understand the situation from their moving perspective we need to transform the spacetime diagram so they no longer appear to be moving – that is, so that their worldline is vertical.
要从它们移动的角度来理解情况，我们需要转换时空图，使它们看起来不再移动--也就是说，使它们的世界线是垂直的。
That's what it means for the spacetime diagram to represent their perspective.
这就是时空图代表他们的观点的意义所在。
Having done so for the outward leg of their journey, it's clear that your twin would say that leg of their journey took them – I dunno, what's that look like?
在他们向外旅行时这样做了，很明显双胞胎会说他们旅行的那段路把他们带走了-我不知道，那看起来是什么样子？
About 5 and 2/3 seconds?
大约5又2/3秒？
And then they turned around and headed back to earth, which corresponds to a different moving perspective.
然后他们转身返回地球，这与不同的移动视角相对应。
Let's transform things to see how they look from that perspective; that is, so that the worldline of that leg of the journey is vertical.
让我们对事物进行变换，看看它们从那个角度看起来是什么样子；也就是说，这段旅程的世界线是垂直的。
Having done so, it's clear that your twin would say that the return leg of their journey took them – again, looks like about 5 and 2/3 seconds.
这样做之后，很明显，你的双胞胎会说他们的回程带他们去了-同样，看起来大约是5又2/3秒。
So from the perspective of your twin, their whole journey takes 5.66+5.66=11.3 seconds, while for you it took 12 seconds.
所以从你双胞胎的角度来看，他们的整个旅程需要5.66+5.66=11.3秒，而你需要12秒。
So you, who stayed put, are older.
所以你，呆在原地不动，年纪更大了。
The key to why the two of you do in fact age differently is that your traveling twin has two separate perspectives during their journey, while you, staying put, only have one.
你们两个实际上年龄不同的关键是移动的双胞胎在旅途中有两种不同的观点，而你留在原地只有一种观点。
And that's the resolution to the linguistically confusing twins situation, demonstrated with a hands-on spacetime diagram
这就是解决双胞胎在语言上令人困惑的方法，用一个实际操作的时空图来演示
- I want to say that even though I knew and understood the math and physics behind this, my belief in the trueness of the solution to the twins paradox went up a million times the first time I actually measured the times each twin experienced with my hands, in real life like this.
——我想说的是，尽管我知道并理解这背后的数学和物理， 当我第一次用我的手测量每个双胞胎在现实生活中的经历时，我对双生子悖论解决方案的真实性的信念增加了一百万倍，就像这样。
So I hope that I've managed to capture even a small percentage of that gut level belief in this video.
所以我希望我能在这段视频中捕捉到哪怕是一小部分的直觉信念。
You also don't have to use Lorentz transformations to figure out the solution to the twins paradox if you know about proper time (spacetime intervals),
如果你知道适当的时间(时空间隔)，你也不必使用洛伦兹变换来找出双生子悖论的解决方案，
because spacetime intervals are/proper time is a way of calculating the time that passes for somebody according to their perspective.
因为时空间隔是/适当的时间是一种根据某人的视角计算经过的时间的方法。
So in the case of your twin, on each leg of their journey they take 6 seconds to travel the distance light would travel in two seconds (or, 2 light-seconds),
因此，就你的双胞胎来说，在他们旅行的每段路程中，他们需要6秒才能走完光在2秒(或2光秒)内行驶的距离，
and taking the square root of the difference of those numbers squared gives a proper time of 5.66 seconds for each leg of their journey – exactly what we measured on the spacetime globe!
取这些数字的平方的平方根可以得出他们每段旅程的适当时间为5.66秒-正好是我们在时空球体上测量的！
If you're interested in a little more insight into how the “each person views time as passing more slowly for the other” part of the paradox actually makes sense (and I promise, it does),
如果你有兴趣更深入地了解矛盾中“每个人都认为时间过得更慢”这一部分实际上是如何说得通的(我保证，的确如此)，
I have another pair of videos diving into more detail on the twins paradox that I highly recommend you check out!
还有另外两个视频，它们深入探讨了双生子悖论的更多细节，我强烈建议你们去看看！
And to deepen your personal understanding of the resolution to the twins paradox, I highly recommend Brilliant.org's course on special relativity.
为了加深你对双生子悖论的理解，我强烈推荐Brilliant.org的狭义相对论课程。
There, you can work through the calculations I've glossed over in a step-by-step guided exploration, giving you essential hand-on experience with spacetime intervals and other tools of relativity along the way.
在那里，你可以完成我在逐步引导的探索中略去的计算，在这个过程中，你可以亲身体验时空间隔和其他相对论工具。
The special relativity questions on Brilliant.org are specifically designed to help you go deeper on the topics I'm including in this series, and you can get 20% off of a Brilliant subscription by going to Brilliant.org/minutephysics.
Brilliant.org上的狭义相对论问题是专门为帮助你深入了解我在本系列文章中涉及的主题而设计的，如果你想订阅Brilliant，可以登录Brilliant.org/minutephysics获得八折优惠。
Again, that's Brilliant.org/minutephysics which gets you 20% off premium access to all of Brilliant's courses and puzzles, and lets Brilliant know you came from here.
再次强调，那就是Brilliant.org/minutephysics，在这里你可以以20%的优惠访问Brilliant的所有课程和题目，让Brilliant知道你是从这个视频来的。
