评论
打印
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,
视角的改变是由一个所谓的洛伦兹变换来表示的，
which is a kind of squeeze-stretch rotation of spacetime that I've mechanically implemented with this spacetime globe.
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。
A quick reminder - spacetime diagrams plot position on the horizontal axis and time on the vertical axis,
快速提醒一下--时空图画出了横轴上的位置和垂直轴上的时间，
and something moving as time passes traces out a path through spacetime called a worldline.
随着时间流逝而移动的物体在时空中划出了一条称为世界线的路径。
One of the first things you might notice about Lorentz transformations is that events that were at different places at the same time before the transformation aren't at the same time after the transformation.
关于洛伦兹变换，你可能注意到的第一件事就是变换前在不同地方同时发生的事件在变换后就不同时发生了。
This means that from the perspectives of people going different speeds, simultaneous events for one person won't be simultaneous for the other, and vice versa.
这意味着，从速度不同的人的角度来看，一个人的同时事件不会对另一个人同时发生，反之亦然。
For example, if from my perspective these two boxes spontaneously combust at the same time,
例如，如果在我看来，这两个盒子同时自燃，
and you're moving at a third the speed of light to my right, then from your perspective,
你正以三分之一的光速向我的右边移动，那么从你的角度来看，
that is, the perpective from which you're not moving so your worldline is purely vertical,
也就是你没有移动的角度，所以你的世界线是完全垂直的，
from your perspective the box on the right will combust first, and the box on the left will combust second.
从你的角度来看，右边的盒子会首先燃烧，左边的盒子会第二个燃烧。
The takeaway here is that our universe has neither an absolute notion of time nor an absolute sense of simultaneous events,
这里的结论是，我们的宇宙既没有绝对的时间概念，也没有绝对的同时发生事件的概念，
and that simultaneity breaks down more the farther away from each other two things are – a box even farther to the left that from my perspective simultaneously spontaneously combusts with the others will,
同时性分解得越远，两件东西彼此之间的距离就越远——在我看来，更左边的盒子会和其他东西同时自燃，
from your moving perspective, be even farther out of sync with the box on the right.
从你移动的角度来看，会与右边的盒子更不同步。
This is described by the time part of the Lorentz Transformation equations, the part that says t new = gamma times t minus v times x over c squared).
这是由洛伦兹变换方程的时间部分描述的
Because of the x in there, the farther away an event is from you, the more its time from the new perspective will be out of sync with events closer to you.
因为x在这里，一个事件离你越远，从新角度来看，它的时间与离你越近的事件就越不同步。
Though because of the factor of c squared in the denominator, which is huge,
虽然由于分母中c的平方因子非常大，
it's hard to notice anything being out of sync until either your speed or distance to the object in question are really really really big
所以很难注意到有任何东西不同步，除非你的速度或到这个物体的距离非常非常非常大，
– like, you'd have to be going half the speed of light and be comparing things farther apart than the earth and moon before things would become more than 1 second out of sync.
你必须以光速的一半的速度，比较距离比地球和月球更远的物体，它们才会出现超过1秒的不同步。
But in that case, events that were simultaneous from my perspective really would be out of sync for you!
但在这种情况下，从我的角度来看，同时发生的事件对你来说真的是不同步的！
As surprising as this may seem, it might feel more familiar and comfortable when you remember that this “getting out of alignment” phenomenon happens to points at the same place in space, too,
尽管这看起来令人惊讶，但当你想起这种“偏离直线”的现象也发生在空间中相同位置的点时，你可能会感到更熟悉和舒适，
which is literally what we think of as defining motion – from my perspective, this box is at the same position at different times
这就是我们认为的定义运动的东西，从我的角度来看，这个盒子在不同的时间处于相同的位置
– that is, it's not moving; maybe, “simulspacious”– but from your moving perspective it's at different positions at different times – it is moving.
也就是说，它不动了; 也许，同时发生——但从你移动的角度来看，它在不同的时间处于不同的位置——它在移动。
Relativity of simultaneity is just the other side of the coin – the fact that events that happen at the same time at different spatial positions happen at different times when viewed from a moving perspective.
同时性的相对性只是硬币的另一面-从移动的角度来看，在不同空间位置同时发生的事件发生在不同的时间。
All together, in our universe, the takeaway is this: events that were previously either all at the same place or all at the same time get out of alignment with each other when you change to a moving perspective.
总之，在我们的宇宙中，结论是:以前所有的事件要么都在同一个地方，要么都在同一时间发生，当你改变到一个移动的视角时，它们就会相互偏离。
A big thanks again to Mark Rober for making the spacetime globe a reality, and to dive more into the details of relativity of simultaneity,
再次感谢Mark Rober让时空地球成为现实，并深入研究了同时性相对论的细节，
I highly recommend heading over to Brilliant.org's course on special relativity that they've been developing simultaneously with this video series (well, at least, simultaneous from my perspective).
我强烈推荐大家去Brilliant.org上的狭义相对论课程，这门课是和这个视频系列同时进行的(至少在我看来是同时进行的)。
There, you can explore custom scenarios and do actual puzzles and problems that help you build on what you learned in this video, like figuring out how laser tag would work at relativistic speeds!
在那里，你可以探索自定义的场景，并解出实际的谜题和问题，帮助你巩固你在这个视频中学到的东西，比如弄清楚激光标签如何在相对论速度下工作!
The special relativity questions on Brilliant.org are specifically designed to help you go deeper on the topics I'm including in this series,
Brilliant.org上的狭义相对论问题是专门设计来帮助你深入了解我在这个系列中提到的主题的，
and you can get 20% off of a Brilliant subscription by going to Brilliant.org/minutephysics.
你可以通过登录Brilliant.org/minutephysics获得Brilliant订阅8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，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。
