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I recently received this question via email: Hello there,
Imagine we build a giant ring around the whole globe, perfectly round, no ups and downs.
What you didn't know is that i installed explosives all around on each pole holding it up, and
then boom.
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?
Best regards, Martin from Sweden.
First off, Martin, that was sneaky.
I cannot condone secretly installing explosives on poles holding up infrastructure projects.
Second, I have a feeling you might really like the planet Saturn.
And Third, fun question!
The answer depends a lot on how strong the ring is, but in general you've touched upon
an idea called symmetry breaking.
As you've realized, a perfectly symmetric ring doesn't have any particular reason to
fall or break in any one point!
Like a perfectly balanced pencil, which way will it fall?
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, 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.
Like how in tug of war if both sides pull the same amount the rope won’t move).
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.
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.
As for “will it start spinning like crazy”?
I think you might be referring to the idea that the earth is spinning to the east “underneath”
the ring – well, I have a whole other video about that, that you should definitely check
out.
Thanks for your question, and stay away from
the high explosives.