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The Earth's magnetic field has been tremendously useful
over the years. A nice aligned field pointing to fixed
points
at the top and bottom of the globe is very attractive to
navigation enthusiasts. Once Harrison knocked together a
reasonable clock, figuring out where you were was
possible
even in uncivilized regions*.
As it turns out, the magnetic field isn't the reliable old
workhorse we assumed it to be. Instead, it wanders
about
like it doesn't have a job. Clearly, it needs boundaries.
The magnetic field strength of the Earth is weak. 50
micro
Tesla at the surface. Instead of furiously issuing
navigational corrections, we can simply turn the Earth
into
an electromagnet. 50 microTesla will need about 100
million Amps, which suggests about 1.5m^2
superconducting cable running a couple of loops around
the equator. Once the current is flowing, we won't need
to
worry about anything apart from cooling the cable and
barnacle accumulation, probably.
Careful choice of cable orientation will fix the Earth's
magnetic field right through True North where it's
supposed to be. No corrections no messing about.
Solar storm protection and aurora light shows are
delightful features that nations may draw mutual benefit
from, on the understanding that payments are prompt,
sudden discontinuation of the service may cause distress.
*There are many subtle techniques used in navigating
uncivilized regions of the planet. Often these are specific
to the location, which is tricky if you don't know which
location you're in. Some say that location is easily
derived
from a synthesis of environmental cues, but what if you
can't see them because there's a great big French
signpost
in the way?
Movable London
https://www.mortale...mortal-engines.html
[bs0u0155, Mar 11 2019]
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Annotation:
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//1.5m^2 superconducting cable// I thought the point of a
superconducting cable was that it was superconducting? In
which case, why does it need to be so fat? And how would
barnacles adversely affect its performance? |
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//why does it need to be so fat?// |
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Not my subject, but there's a limit to the current density
apparently. |
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Actually, there might be a cheaper way to do this. A much
thinner non-superconducting wire could be pumped with a
few billion amps. It would vaporise in the blink of an eye, but
the resulting plasma ought to sustain conduction for at least a
few microseconds. During that time, the magnetic field ought
to be sufficient to magnetize any magnetizeable minerals, so
we'd be good to go until tectonics messed it all up again. |
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Also, we ought to pilot this scheme on Mars. Giving it a
magnetosphere again ought to mean we can pour some
atmosphere on it, without having it solar-winded away. I
suppose the only downside would be that eventually Mars and
Earth would end up stuck together. |
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//tectonics messed it all up again// |
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Well, that's something else that needs solving. I'm fine with
India having a long crash into asia, but we have to maintain
standards. Greenwich stays where it is. |
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//pilot this scheme on Mars.// |
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Smaller and the cooling is almost pre-solved. |
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//Greenwich stays where it is.// That's an administrative
matter. When Greenwhich is several thousand miles north-
east of its present location, the North and South poles and all
the longitude lines will just have to be shifted. Of course,
there's always subduction to worry about but, once again, we
can simply redefine all surface features to be mountains. |
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Nice, just what humanity needs, a great leap towards the invariable. |
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Give my regards to Gibraltar, [Ian]. As far as I could tell from
when I was last there, it's basically the UK but in 1977. Mind
you, that was back in 2016. |
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The natural location for the EM north pole would of
course be Warsaw. |
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// //Greenwich stays where it is.// That's an administrative matter. // |
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Cut round Greenwich. Jack it up and slide some rollers underneath. Then just move it until it has the correct position relative to the pole. |
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//Jack it up and slide some rollers underneath. // |
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They did it in a crappy movie <link> |
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Apparently the books were much better, but not known
outside of Australia, so maybe they didn't think it was worth
it to make a good movie for North American audiences? |
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//didn't think it was worth it to make a good movie for
North American audiences?// |
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There's plenty of good movies made for the American
audience. I think one reason for the recent downturn in
movie quality is that movies are being made for appeal in
markets outside America. To make movies appeal to S.E.
asia, AND the Indian subcontinent AND Europe/USA, you
have to cut out anything that relies on specific locations,
particular people or events. It's better if there's no dialog,
and sadly, evidence of thought. |
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