Timeline for An electromagnetic space elevator?
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
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| Sep 5, 2014 at 14:06 | comment | added | Ron Maimon | @Floris: You don't need to do work to get the thing off the ground, you supply the current once, it's next to no work, then you cool it to superconducting and it traps the current in there. Then you let it go, and it rises up, the Earth just slows down as it lifts the thing. The magnetic field of the Earth is ultimately because the core is rotating. The cryostat doesn't need to be heavy compared to the wire, the wire can be a bundle of wires 1m in radius, the cooling is at the boundary. This is perfectly feasable. | |
| Sep 5, 2014 at 5:55 | comment | added | Floris | @RonMaimon - why do you say that the earth's rotation provides the lift force? I assumed the magnetic field would be the one that mattered - and you would have to do work (by supplying current into a giant inductor) in order to get this thing off the ground. The mass of the wire isn't what will kill you - it's the cryostat around it (even without the mass of the helium)... | |
| Sep 16, 2012 at 7:31 | comment | added | Ron Maimon | Sorry, ignore the top comment above, the expulsion of magnetic field is not important at all, the lift force is determined by conservation laws away from the wire, and it doesn't care about whether the wire is superconducting or not. The lift is provided by the Earth's magnetic field, and the lift force is provided by the Earth's rotation--- the Earth will slow down infinitesimally that's all. | |
| Sep 16, 2012 at 7:02 | comment | added | Ron Maimon | @Everyone: You are right, my idea that it is stupid was the stupid one. The idea works. The superconductor expels the field, but the current-magnet force is the same as if it didn't, the force just acts on the surface of the wire instead of in the bulk (or around a vortex). The field stresses that transmit the force are the same incoming around the wire, and the details of the interior don't matter except to the detailed force distribution. | |
| Sep 16, 2012 at 3:36 | comment | added | Everyone | @RonMaimon: I beg to differ. It is not a stupid idea - perhaps unusable given the state of technology, but certainly not stupid. Then again, I may be prejudiced because I'd been entertaining a similar thought (+: | |
| Sep 15, 2012 at 21:24 | comment | added | Ron Maimon | This is not true--- nothing is going up, my idea is stupid. | |
| Sep 15, 2012 at 19:19 | history | answered | jcohen79 | CC BY-SA 3.0 |