From: The Low Golden Willow (phoenix@ugcs.caltech.edu)
Date: Wed Oct 29 1997 - 15:38:01 MST
On Oct 29, 10:36am, Anders Sandberg wrote:
} physicist, but I would argue it is unlikely. The core is believed to
} contain not just nickel-iron, but other heavy elements. This suggests
} to me that the core cannot form a nice crystal lattice, and likely has
What logic prompted this, Anders? Rubies/sapphires are high quality but
impure crystals of corundum, itself a complex of Si, Al, and O. And we
can make crystals out of protein, or for that matter, viruses.
The core is dense and magnetic, which implies a metal; iron is a very
common element, and has density, elasticity and electrical properties
similar to those of the core. (I quote Britannica.) I'm not sure how
they determined electrical properties of the core; the other two would
be from seismic tomography. As for crysttalline nature, well, at those
tempertatures and pressures you *assume* something is crystalline.
The core is somewhat less dense than pure iron at core conditions, so
you guess it is impure, and you guess the impurities from abundances and
chemisty. And by modelling; a 90 % iron core with sulfur, oxygen, and
possibly a bit of extra crud matches seismic observations.
} The most popular current theory is that the magnetic field is produced
} by dynamo currents in the liquid outer core, driven by the earth's
} rotation. The shifts in the magnetic field are caused in this model by
Yep. I think there's still a good bit of ignorance; last I heard
someone was saying the core doesn't rotate at the same rate as the rest
of the Earth. I forget all details.
Merry part,
-xx- Damien R. Sullivan X-) <*> http://www.ugcs.caltech.edu/~phoenix
"Dragonlords fight for honor, Iorich nobles fight for justice, Jhereg
nobles fight for money, and Dzurlords fight for fun."
-- Steven Brust, a Vlad Taltos book
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