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I recently received this question via email:
我最近通过电子邮件收到了这个问题:
Hello there, Imagine we build a giant ring around the whole globe, perfectly round, no ups and downs.
你好,想象一下，我们在地球周围建立了一个巨大的环，完美的圆形，没有起伏。
What you didn't know is that I installed explosives all around on each pole holding it up, and then boom.
你不知道的是我在每根柱子上都装了炸药，然后就爆炸了。
![M60%1HV`CDYE)7B7[S]KR4Y.png](http://upload.kekenet.com/2021/0926/73021632655179.png "M60%1HV`CDYE)7B7[S]KR4Y.png")
All the poles break at the same time. What will happen to the ring? Will it just sit there in the air? Or will it fall down? Will it start spinning like crazy?
所有的杆子同时断裂。环会怎么样? 它会在空中停留吗?还是会倒塌?它会开始疯狂地旋转吗?
Best regards, Martin from Sweden.
最好的问候，来自瑞典的马丁。
First off, Martin, that was sneaky.
首先，马丁，这太卑鄙了。
I cannot condone secretly installing explosives on poles holding up infrastructure projects.
我不能容忍在支撑基础设施项目的电线杆上秘密安装炸药。
Second, I have a feeling you might really like the planet Saturn.
其次，我有一种感觉，你可能真的很喜欢土星。
And Third, fun question!
第三，有趣的问题！
The answer depends a lot on how strong the ring is, but in general you've touched upon an idea called symmetry breaking.
答案很大程度上取决于环的强度，但一般来说，你会接触到一个叫做对称破缺的概念。
As you've realized, a perfectly symmetric ring doesn't have any particular reason to fall or break in any one point!
正如你已经意识到的，一个完美对称的环没有任何特别的原因掉下来或在任何一点破裂!
Like a perfectly balanced pencil, which way will it fall?
就像一支完美平衡的铅笔，它会往哪个方向掉?
Anyway, if the ring is really really strong, then it should just stay exactly where it is, "hovering", though that actually means being held up by its own strength,
不管怎样，如果这个环非常非常结实，那么它就应该原地不动，“悬停”，尽管这实际上意味着被自己的力量支撑着，
because each part will be gravitationally pulled toward the center of the earth, and since those forces are spread equally around the ring in a symmetric way they’ll cancel out.
因为每个部分都会被重力拉向地球中心，并且由于这些力以对称方式均匀分布在环周围，它们会相互抵消。
Like how in tug of war if both sides pull the same amount the rope won’t move.
就像在拔河比赛中，如果双方的拉力相同，绳子就不会动。
Now, if the ring’s not sufficiently strong, it might buckle in places and become scrunched up, like the coins that my friend Dianna shrunk by putting them in a very strong, very quickly changing magnetic field.
现在，如果这个环不够牢固，它可能会在一些地方弯曲，变成一团，就像我的朋友戴安娜把硬币放在一个非常强大，变化非常快的磁场中缩小了一样。
It’s interesting to note that the properties of circumferences mean you’d only have to take out a few meters for the ring to be small enough to just lie on the ground.
有趣的是，圆周的特性意味着你只需要取出几米，环就足够小，可以放在地上。
As for “will it start spinning like crazy”?
至于“它会开始疯狂地旋转吗?”
I think you might be referring to the idea that the earth is spinning to the east “underneath” the ring.
我想你可能指的是地球在环“下方”向东旋转。
