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I recently received this question via email: Hello there,
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Imagine we build a giant ring around the whole globe, perfectly round, no ups and downs.
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What you didn't know is that i installed explosives all around on each pole holding it up, and
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then boom.
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All the poles break at the same time.
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What will happen to the ring?
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Will it just sit there in the air?
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Or will it fall down?
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Will it start spinning like crazy?
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Best regards, Martin from Sweden.
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First off, Martin, that was sneaky.
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I cannot condone secretly installing explosives on poles holding up infrastructure projects.
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Second, I have a feeling you might really like the planet Saturn.
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And Third, fun question!
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The answer depends a lot on how strong the ring is, but in general you've touched upon
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an idea called symmetry breaking.
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As you've realized, a perfectly symmetric ring doesn't have any particular reason to
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fall or break in any one point!
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Like a perfectly balanced pencil, which way will it fall?
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Anyway, if the ring is really really strong, then it should just stay exactly where it
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is, "hovering", though that actually means being held up by its own strength, because
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each part will be gravitationally pulled toward the center of the earth, and since those forces
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are spread equally around the ring in a symmetric way they’ll cancel out.
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Like how in tug of war if both sides pull the same amount the rope won’t move).
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Now, if the ring’s not sufficiently strong, it might buckle in places and become scrunched
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up, like the coins that my friend Dianna shrunk by putting them in a very strong, very quickly
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changing magnetic field.
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It’s interesting to note that the properties of circumferences mean you’d only have to
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take out a few meters for the ring to be small enough to just lie on the ground.
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As for “will it start spinning like crazy”?
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I think you might be referring to the idea that the earth is spinning to the east “underneath”
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the ring – well, I have a whole other video about that, that you should definitely check
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out.
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Thanks for your question, and stay away from
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the high explosives.