
New kind of metal in the deep Earth - llambda
http://www.sciencedaily.com/releases/2011/12/111219112216.htm
======
ChuckMcM
The truly fascinating part of this is how FeO is a conductor at these
temperatures and pressures, but ceases to be so when the temperature or
pressure drops. So for you computational physics students out there, consider
the effects of a current in a moving current where the conductivity is
determined by temperature and pressure. That is a simulation that has to take
into account the thermodynamics of heat transfer out of the core, the
temperature changing effects of constricting magnetic fields, and the effects
of shock waves in a fluid in motion.

Basically we don't have the science to describe the behavior of a planetary
core made up of this type of material! Is that cool or what.

~~~
rubidium
We definitely have the science to describe this.

It just happens to be very complicated. You're right in that it's a mixture of
E&M, thermodynamics, and fluid mechanics. Whether it becomes computationally
prohibitive to model is something I am unsure of, but may be possible with
some simplifying assumptions.

Edit: after a bit more research, I found a paper where, if I follow correctly,
they are laying out a framework for creating such a model:
<http://arxiv.org/abs/1004.1611>

~~~
ChuckMcM
Seriously? Except its not a plasma, its a fluid, and computational fluid
dynamics (CFD) simulations don't include (at this stage) electromagnetic
forces. Show me a paper that can describe a fluid in motion where the force on
each element is computed as a function of the electromagnetic state, the
thermal state, and the viscosity state of each other element and I'll show you
a candidate for a Nobel prize.

At least in the open literature I haven't seen CFD models that consider the
influence of elements beyond a few centimeters, the magnetic forces in the
Earth's core move elements meters, if not kilometers, away so the date sets do
get very strange, and you have to mix in that if they cool to much or you hit
an eddy current and the pressure drops the current gets cut off and the
electrodynamic forces stop.

~~~
Bjartr
So these are the guys to watch then?

<http://www.youtube.com/watch?v=2dm4RvDSkUY>

~~~
ChuckMcM
If you can blend that with a CFD simulation and then add in the changes in
conductivity as the material goes in an out of its conductive and non-
conductive modes sure.

Its the latter bit that seems so mind bending to me. MHD simulations start
with a plasma and it can be conducting throughout the simulation in all
places.

CFD simulations deal with the forces between elements that express as
viscosity, turbulent, and laminar flows.

MHD assumes that elements in the flow are _always_ affected by the electro-
magnetic forces in play, CFD doesn't account for electro-magnetic forces.

CFD assumes that the elements in the flow are only affected by the forces of
nearby elements and not the actions or state of elements that are further
away.

An FeO simulation has to combine them somehow, and account for whorls and
eddies converting elements from the MHD domain into the CFD domain and then
back again.

Anyway, I am looking forward to the papers on this stuff. It combines two
areas I enjoy, complex systems and physics!

~~~
troystribling
Magnetohydrodynamics (MHD) is the combination of Maxwell's Equations in a
moving frame of reference and The Navier Stokes Equation. So it includes both
the impact of inertial and electromagnetic forces of the flow. MHD is the long
wavelength limit of kinetic (particle) plasma theory. The Earths core has in
the past been modeled as an MHD fluid but it is usually assumed to be
incompressible. I am not aware of compressible models but I have not worked in
this field in a decade.

------
JonnieCache
To save you reaching for gunits or doing any upsetting mental arithmetic,
4000°F == 2204°C, and 3000°F == 1649°C.

~~~
jberryman
So... really hot.

------
tezza
On a related note, I was astonished how many different states water (H20) can
be in.

Many more than just solid, liquid, gas.

.

See <http://www.lsbu.ac.uk/water/phase.html>

My ice goes up to ice-eleven (XI) ?

~~~
khafra
Thankfully, it skips IX.

~~~
jarin
<http://en.wikipedia.org/wiki/Ice_IX>

------
nvk
Disappointed, thought we would be expanding the Periodic Table.

~~~
guelo
The periodic table is pretty much complete at this point, the super-heavy
elements after about 112 are very unstable and are probably very rare in
nature.

~~~
Confusion
There are however even heavier elements that are hypothesised to be stable. In
that sense, the periodic table is not complete.

    
    
      probably very rare in nature.

I don't know the scope you had in mind, but this seems to suggest these
elements may occur naturally on earth. Just to be on the safe side, I want to
point out that they don't. They just don't occur at all on earth, outside of
laboratories for near infinitesimal amounts of time.

The probability of them occurring naturally in cosmic-scale events is also
extremely small. For all practical purposes, probably for at least a thousand
year to come, these elements do not exist naturally.

~~~
guelo
Any condition you can create in a lab probably exists somewhere in the
universe. There's probably a planet of molten Californium somewhere out there
being bombarded by Einsteinium asteroids.

~~~
Confusion
That's only true under the assumption of an infinite universe, in which even
an event of the smallest probability will take place. Let's stick to the
observable universe: it won't happen there.

------
noonespecial
Sounds like the kind of thing that would sent Tesla running back to his lab
the moment he learned of it.

------
Tloewald
I wonder how the pressures were achieved. I remember a sciam article way back
which discussed attempts to create metallic hydrogen in the lab using, in
essence, g-clamps. (Only a tiny amount of substance could fit into the
apparatus, of course. Still it was amazing that such a simple device could
achieve the necessary pressure.)

~~~
mhb
Diamond anvil?

<http://en.wikipedia.org/wiki/Diamond_anvil_cell>

~~~
Tloewald
Yup, looks like the exact thing.

------
jarin
Kind of makes you wonder why Mars doesn't have a magnetic field then?

Its composition is similar to Earth's, and I assume that it's big enough to
have similar pressures and temperatures closer to the core?

~~~
EwanG
Mars is about half the size of Earth, so it's possible that is too small to
make enough of this conversion happen to generate a magnetic field. Also some
theories of Mars formation would lead to a different composition of its core
due to prior collision(s).

------
nsxwolf
Do the electrons really get squeezed closer to their nuclei? I thought that
only happened in massive collapsing stars where gravity overpowers everything.

~~~
InclinedPlane
There's a continuum. In the cores of stars that continuum bumps up against the
physical limits of electron degenerate (white dwarf) matter. But even within
ordinary planets like our own solid matter is compressed to a significant
degree. For example, even though Earth's inner core is primarily comprised of
Iron and Nickel it is compressed to such a degree that it is denser than Lead.

~~~
samstave
Disclaimer: I have no clue what I am talking about

What if gravity is an emergent result from the compression of matter? The
greater the compression, the greater the density and gravity?

~~~
chc
"The greater the compression, the greater the density" is essentially
tautological. Of course packing the same amount of stuff in a smaller space
makes it more dense. It's true in the same way the statement "Enlarging things
makes them bigger" is true.

But as for gravity, no. Gravity is a function of mass. Compressing a body into
a smaller space will not increase the gravity you experience at a given
distance from the mass's center of gravity (though it will allow you to get
closer to the center of gravity). If you magically replaced the Sun with a
black hole of equal mass, the planets would continue their orbits undisturbed
— even though a black hole's singularity is infinitely dense and the Sun is
less dense than the Earth on average.

~~~
samstave
Thanks for that reply!

------
politician
Banish the thought, but for a moment, I thought of dwarves.

------
LearnYouALisp
At 690,000 atmospheres, you can see this too!

------
ryandvm
Heavy.

