Dumb question: why is it hard to make something spin really fast?
Simple example: put your frictionless spherical cow on a spinny plate. Make it a very small cow; it's only there to have a point of rotation. Why frictionless? You don't want its butt to catch fire. Why spherical? It'll need to maximize volume dedicated to arm muscles; see below.
Have the cow hold two ropes, each leading to a full-sized cow 10m away. Apply force to those cows (blow on them, or magnetize them and do a solenoid thing, or just make them very gassy cows and orient their spherical butts in opposite directions). Get them spinning at 1Hz. (This is very fast; remember the diameter is 20m.) Now have the middle cow pull the ropes, shortening them to 10cm. It's now spinning at 1Khz. 10mm gives 1Mhz. Conservation of angular momentum, baby.
Do this in a vacuum in microgravity, and you don't need the center cow.
Sure, if you're doing this at a bovine scale, the tension is ridiculously large. What makes it infeasible at a small scale?
So, if you use eddy currents to delay the phase of an exciting field long enough that the object those eddy currents are inside of can spin more than 90 degrees, the response eddy current fields now AID instead of opposing the original field?
This sounds quite a bit like what Steorm[1] was doing years ago. If ultraconductors[2] worked, you could actually build a mechanical device that had losses low enough to actually gain energy once a critical speed were obtained.
sfink ·4 hours ago
Simple example: put your frictionless spherical cow on a spinny plate. Make it a very small cow; it's only there to have a point of rotation. Why frictionless? You don't want its butt to catch fire. Why spherical? It'll need to maximize volume dedicated to arm muscles; see below.
Have the cow hold two ropes, each leading to a full-sized cow 10m away. Apply force to those cows (blow on them, or magnetize them and do a solenoid thing, or just make them very gassy cows and orient their spherical butts in opposite directions). Get them spinning at 1Hz. (This is very fast; remember the diameter is 20m.) Now have the middle cow pull the ropes, shortening them to 10cm. It's now spinning at 1Khz. 10mm gives 1Mhz. Conservation of angular momentum, baby.
Do this in a vacuum in microgravity, and you don't need the center cow.
Sure, if you're doing this at a bovine scale, the tension is ridiculously large. What makes it infeasible at a small scale?
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colanderman ·7 hours ago
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mikewarot ·6 hours ago
This sounds quite a bit like what Steorm[1] was doing years ago. If ultraconductors[2] worked, you could actually build a mechanical device that had losses low enough to actually gain energy once a critical speed were obtained.
[1] https://en.wikipedia.org/wiki/Steorn
[2] https://patents.google.com/patent/US5777292A/en
(Claim 7 is for material with a conductivity of 10^11 S/cm, which is 150,000 times better than copper)
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bloopernova ·9 hours ago
Would this mean that a rotating body in space would eventually slow down? In other words, amplifying EM radiation draws energy from angular momentum?
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cdiamand ·9 hours ago
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