Slashdot Mirror
Earth's Core Made In Miniature
ananyo writes "A 3-meter-tall metal sphere full of molten sodium is about to start work modeling the Earth's core. The gigantic dynamo, which has taken researchers ten years to build, 'will generate a self-sustaining electromagnetic field that can be poked, prodded and coaxed for clues about Earth's dynamo, which is generated by the movement of liquid iron in the outer core.'"
Suddenly I'm having a craving for a Cadbury Cream Egg.
Do you know what happens with practice and theory? In theory, they are both the same. In practice, they are not.
Be cause none of the theories, Magneto Hydro Dynamics (MHD), the Vlasov Equation, etc... are correct. The equations are two complex to solve so they have to make approximations. You need experiment to understand what terms are important and what terms are wrong. Plus a lot of times theorists use rediculus scaling parameters such that these phenomena can never happen in nature.
In science nobody believes the theory except the theorist and everybody believes the experiment except the experimentalist.
Yawn! Wake me when they have a dual-core earth.
The single-core model is bound to revolve to slowly!
"That's the way to do it" - Punch
And this distinction is noteworthy because you can measuring what happens in practice, find where it doesn't meet the theory, and revise your theory. This is how science gets done.
Plus a lot of times theorists use rediculus...
Wow, and here I am thinking calculus was hard.
The experiment was previously filled with water in order to resolve the fluid flow. Water and Sodium have very similar viscous properties so long as you have the temperatures correct. Sodium is also opaque so you can't use lasers and are limited to a combination of ultrasound and flow tomography (basically, backing out the flow from the induced magnetic field), so its somewhat common practice to do a water model of sodium experiments. Lathrop's Water part of the experiment lasted 4ish years? (I think, perhaps between 2 and 4?) because he encountered some interesting hydrodynamic effects. I saw Dr. Lathrop speak at a conference about 3 weeks ago and they were about halfway thru the fill process then, so this article lines up quite nicely with what would have been a reasonable completion time.
No highspeed cameras, but here you go - disposal of a couple of 1000 pounds of sodium metal by dumping it into a lake. Old newsreel footage from a time when men were men and chemists were the most manly of them....
Ubi solitudinem faciunt, pacem appellant.