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Earth's Core Made In Miniature

Posted by Unknown on from the evil-geniuses-for-a-molten-tomorrow dept.

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.'"

41 of 175 comments (clear)

  1. Re:Woohoo! by Anonymous Coward · · Score: 3, Funny

    what?

  2. Re:Woohoo! by durrr · · Score: 4, Interesting

    Next step is to drop the content of the sphere into a lake surrounded by high speed 4k cameras with hardened storage units.

  3. spherical ... in vacuum by mapkinase · · Score: 2

    In other words, they created a spherical model of Earth in vacuum.

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  4. Craving by Anne_Nonymous · · Score: 5, Funny

    Suddenly I'm having a craving for a Cadbury Cream Egg.

    1. Re:Craving by ae1294 · · Score: 2

      Suddenly I'm having a craving for a Cadbury Cream Egg.

      Be sure to microwave it for an hour first to get the right effect on chomping down.

  5. How they know... by gr8_phk · · Score: 2, Interesting

    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.'

    They probably know this physical model will exhibit a magnetic field because they did a FEA and CFD simulations of the thing. So why then did it have to be built?

    1. Re:How they know... by sslayer · · Score: 5, Informative

      Do you know what happens with practice and theory? In theory, they are both the same. In practice, they are not.

    2. Re:How they know... by RafaelGCPP · · Score: 2

      They probably know this physical model will exhibit a magnetic field because they did a FEA and CFD simulations of the thing. So why then did it have to be built?

      Because simulations do not substitute real experiments. For instance, why would one need LHC if the simulations show the Higgs boson? (Q.E.D.)

      --
      "There is always an easy solution to every human problem -- neat, plausible, and wrong."
      H. L. Mencken
    3. Re:How they know... by Anonymous Coward · · Score: 5, Insightful

      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.

    4. Re:How they know... by nine-times · · Score: 5, Insightful

      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.

    5. Re:How they know... by Anonymous Coward · · Score: 5, Funny

      Plus a lot of times theorists use rediculus...

      Wow, and here I am thinking calculus was hard.

    6. Re:How they know... by JosKarith · · Score: 4, Insightful

      Calculations showed powered flight to be possible - why did Orville & Wilbur build the Flyer?
      Why was the first atomic pile built? Why the first moon shot?
      Because we can. Because theory is all well and good, but to actually have the thing in reality confirms (or disproves, usually dramatically) the theory.

      --
      'Don't worry' said the trees when they saw the axe coming, 'The handle is one of us.'
    7. Re:How they know... by Anonymous Coward · · Score: 4, Funny

      Imagine if it was three complex!

    8. Re:How they know... by TheLink · · Score: 2, Insightful

      I believe the physical model will experience gravity in one direction, whereas the simulated model doesn't have to?

      --
    9. Re:How they know... by DarkOx · · Score: 3, Insightful

      Well powered flight has immediate and obvious useful applications, this thing less so, at least as far as I can see. Powered flight means I can get there faster, or cross rough terrain impossible in other vehicles, etc etc. Giant sphere of super heated liquid salt, not really sure how I can use that. Which is not say that is a reason not build the thing.

      A better analogy would be Orville and Wilbur carving a wooden wing and running around the bike shop with it to feel that it does indeed produce lift when pushed through a fluid like air. Its a required precursor to powered flight, and would more represent this sort of basic research. At some point you have to try things.

      --
      Repeal the 17th Amendment TODAY! Also Please Read http://www.gnu.org/philosophy/right-to-read.html
    10. Re:How they know... by Sockatume · · Score: 2

      Hopefully, the effects they're looking to measure are larger than the anomaly from gravity.

      Of course in the best case scenario, they'd just have a three-metre ball of molten sodium on the ISS, but I don't think NASA can afford to replace all the staff who would die of horror just contemplating the idea. Maybe they could send it up on the vomit comet, or just drop it from a great height? I'd watch a video of that.

      --
      No kidding!!! What do you say at this point?
  6. Re:That doesn't sound right... by Megahard · · Score: 4, Informative

    Well, you could check. Melting point of sodium is 97.72 C.

    --
    I eat only the real part of complex carbohydrates.
  7. Inaccurate Model by Mr+Bubble · · Score: 3, Funny

    This model is inaccurate as it does not provide for the Reptilian space.

    --
    "The world is a construct of forceful imagination. Those who don't know walk around in the reailties of those who do"
    1. Re:Inaccurate Model by DrXym · · Score: 3, Funny

      It's inaccurate because the simulated Earth is not resting on a 4 elephants or a giant space turtle.

    2. Re:Inaccurate Model by rubycodez · · Score: 3, Funny

      That model has been disproven. You'll note the model has support system that quite accurately simulates the stiffness, damping and degrees of freedom of Turtles All The Way Down.

  8. Now work can begin... by Saishuuheiki · · Score: 4, Funny

    ...on our doomsday device to stop the earth's core from spinning.

    Small scale tests first before we build the full-size model.

  9. How can this produce accurate results? by wisebabo · · Score: 3, Interesting

    How can this produce accurate results that will possibly match that of reality? This device (unless they are planning to put it on the space station) will be overwhelmingly influenced by the (real) earth's gravity. Convection will obviously be way off.

    So, unless they are trying to model how the earth's core would act if it were enclosed in a giant metal sphere and placed on a gigantic table subject to one-gee, won't this simulation be way off?

    Even if they put it in space, I'm not sure the simulation would be correct, the forces provided from the self-gravitation would probably be off.

    1. Re:How can this produce accurate results? by u38cg · · Score: 3, Funny

      Alternatively, you could stop worrying about these things, and enjoy the fact you've built a thirteen tonne sphere of rotating molten sodium. Enjoy yourself, you know?

      --
      [FUCK BETA]
    2. Re:How can this produce accurate results? by athmanb · · Score: 4, Insightful

      A team of physicists has worked 10 years on this, writing hundreds of pages of papers to coerce funding out of federal institutes but you can spot the flaw in their plans after 30 seconds of thinking and writing an Internet comment?

    3. Re:How can this produce accurate results? by clickforfreepizza · · Score: 3, Insightful

      I'm sick and tired of this kind of banal and destructive comment. Please read GP again. Is "This cannot work. Case closed." really what you get from it?

      I think GP is trying to understand the experiment. Pointing out issues which are problems according to his current understanding is an excellent first step to learn more.

      Always adding a disclaimer that we are aware that we are no experts would be as superfluous as your answer. Don't you hate it when you teach someone and it goes like this: "Okay, what don't you understand?" - "Well... everything." Pointing out "Here's what doesn't make sense." should be a relatively obvious and welcome form to ask for clarification.

      And even if you do not believe that the poster wants to learn, you could answer him in a constructive manner and thus help others with similar questions. If you cannot or do not want to do that, please ignore him.

    4. Re:How can this produce accurate results? by Sockatume · · Score: 4, Insightful

      Being able to answer that question, and not merely ask it, is why these people get to play with 3-metre balls of molten sodium for a living.

      --
      No kidding!!! What do you say at this point?
    5. Re:How can this produce accurate results? by bruce_the_loon · · Score: 2

      Yes Mr Pizza, "This cannot work. Case closed." is exactly what I read from a comment like that. When someone makes a comment about how the experiment can't possibly work because it might be affected by the gravity, it tells me instantly that the poster knows absolutely nothing about the scientific method and that they believe that building a device that partially matches the reality of earth and will be verified against a model with parameters that take that into account is useless.

      It is exactly the same as the idiot posters about the neutrino speed discrepancy who said that the scientists obviously didn't measure the distance right or something equally idiotic.

      People who post comments like that are irreparable and I made the decision long ago to actively ignore them since it was taking too much energy to try and get a clue into their thick skulls about how science actually works.

      </rant>

      --
      Trying to become famous by taking photos. Visit my homepage please.
    6. Re:How can this produce accurate results? by n3umh · · Score: 2

      How can this produce accurate results that will possibly match that of reality?

      One of the things that we're trying to do is generate a dynamo that offers the same challenges to those who wish to simulate Earth's dynamo while keeping a pretty simple geometry and forcing.

      We don't use convection because the velocities you can get from convection in the lab are too small, even when you crank up "gravity" which is dominated not as much by Earth's gravity but by centrifugal acceleration. Rotating convection in the lab has been done by heating the OUTSIDE and cooling the inner core. The cold dense fluid at the inner core gets flung outward, the light hot fluid at the outside moves inward.

      Centrifugal convection in a sphere is very cool (or in a hemisphere: http://hakusan.s.kanazawa-u.ac.jp/~sumita/%20hemisphere.html) but is not a very likely candidate for dynamo action because convection isn't very vigorous at sane heat fluxes (and by "sane," keep that in context: I'm a dude who thinks spinning 13 tons of sodium isn't really a big deal)

      We're forcing our experiment by spinning the two boundaries at different speeds, which isn't really earthlike at all.. but the real point is to help figure out how to make practical computer models of the dynamo process by having a controlled testbed for studying a turbulent dynamo in a geometry that doesn't require the dynamo simulation community to greatly change their codes. They just have to spin the boundaries of their spherical shell simulation instead of using internal heat sources. The geodynamo simulation community has done a lot of optimization for calculating fluid flow and magnetic field generation in rapidly rotating spherical shells.

      And from the perspective of relevant physics, the rotation and spherical shell geometry allow some internal waves and vortices that are fairly similar to what might happen in the core.

      We can't hope for an exact scale model of the earth that will do earthlike things by itself. Really, we just want to get a laboratory dynamo that has ingredients like rapid rotation and spherical shell geometry. To hit ALL of the parameters correctly to get an exact convective scale model of the Earth's dynamo would probably need something like metallic hydrogen at four million atmospheres pressure (so that it might go into a metallic superfluid state) and a small laboratory black hole at the center.

      This is what I like to call an "engineering challenge."

      -Dan Zimmerman

  10. Good example of the use of physical models... by Zrako · · Score: 3, Interesting

    in relationship to yesterdays article on physical models in the age of computers (http://science.slashdot.org/story/11/12/06/1736231/physical-models-in-an-age-of-computers). This is a great example of when a physical model is invaluable to scientific research even though a computer model could have been used. What happens in theory doesn't always hold true in practice.

  11. Yawn by Oswald+McWeany · · Score: 5, Funny

    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
  12. Re:Woohoo! by Dunbal · · Score: 2

    Better yet make them look like the name of some sheik but upside down.

    --
    Seven puppies were harmed during the making of this post.
  13. Just starting? by Lando · · Score: 3

    Hmmm, knowing that I've seen this before, I decided to go lookabout http://www.popularmechanics.com/technology/engineering/4277476 Ummm so what did they do? Apparently they emptied the thing of the sodium it had in 2009, either that or the 2009 article is in error.

    Not sure if this is all that interesting, appears to just be a pr piece to help ensure people don't forget about them. Not sure why there is a time discrepancy. The show I saw before has some sort of sodium filled ball for measuring magnetic fields, and I assume that it's probably the same one. Since I watch most of my documentaries on Netflix now, I have to assume this thing is several years old.

    --
    /* TODO: Spawn child process, interest child in technology, have child write a new sig */
    1. Re:Just starting? by schiiz · · Score: 5, Informative

      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.

    2. Re:Just starting? by n3umh · · Score: 2

      So, what you're saying is that the popular mechanics article where it specifically says that they were using sodium is false and they were using water?

      Unfortunately, that is the case. We find out about weird stuff like this when the piece comes out. The grand total of all the sodium spinning in the three meter experiment so far has been when Santiago Triana and I melted the partially full sphere and spun the inner shaft and sphere by hand a few weeks ago.

      I'm not sure why the Popular Mechanics people said we were already running sodium... we certainly didn't tell them that or give them that impression. I was taking data in water for my dissertation. Since I graduated we have mostly been doing logistics and sodium-filling engineering and logistics stuff.

      This Nature article is excellent both in the description of the experiments and the projected timeline. Of course things might slip a bit because we always have a lot of work to do, but we DO actually have quite a lot of sodium in there (73% full) and have the rest inbound on a boat from France right now. Won't take too long to top it off. We have a little bit of instrumentation work to do but that's really just wiring some commercially available hall effect sensor into an existing rotating computer. We always have to do some debugging, but we're really quite close.

      -Dan Zimmerman

  14. Re:Drop it into water! by Quiet_Desperation · · Score: 2

    Are they still doing that? It's why I stopped watching. Too much just blowing things up, to much overacted reactions, too much "Warning! Science Content!" as if that's a bad thing...

  15. Re:Woohoo! by Anonymous Coward · · Score: 4, Funny

    what?

  16. Re:That doesn't sound right... by Baloroth · · Score: 4, Informative

    Sodium != salt, which is probably what you are thinking of (seems to be the trend in the comments around yours). Sodium is a metal, not a salt (NaCl is common table salt, which melts closer to 1000C or something).

    --
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  17. Re:Woohoo! by Jeng · · Score: 2

    Prototypes are currently being tested in earth orbit.

    http://www.bigelowaerospace.com/

    --
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  18. mathematical models not great by peter303 · · Score: 2

    A dynamo may have phase changes in it are very hard to model or may require expensive tiny grid cells or modeling accuracy. It was a big announcement in the mid-1990s to model magnetic pole-flipping on a supercomputer. And took three months to compute.

  19. Re:Woohoo! by Mindcontrolled · · Score: 5, Funny

    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.
  20. Re:Somebody please hint... by n3umh · · Score: 2

    Sodium is the best liquid electrical conductor. Order of magnitude better than things like mercury and gallium which are sometimes used in smaller MHD experiments. It's fairly cheap. Gallium is about a thousand dollars a liter and I guess we paid about $7.50/liter for the sodium.

    And it's low density (about the same as water). The fluid mass would be about 75 tons if we used gallium and 170 tons if we used mercury.... (honestly I don't even know if you can buy that much of either of them anyway).

    Sodium is the only game in town for liquid metal dynamo experiments.

    -Dan Zimmerman