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Science

Earth's Core Made In Miniature 175

Posted by Unknown Lamer 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.'"
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Earth's Core Made In Miniature More

Earth's Core Made In Miniature

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  • spherical ... in vacuum (Score:3)

    by mapkinase ( 958129 ) on Wednesday December 07, 2011 @11:24AM (#38291056) Homepage Journal

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

  • Craving (Score:5, Funny)

    by Anne_Nonymous ( 313852 ) on Wednesday December 07, 2011 @11:27AM (#38291076) Homepage Journal

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

  • How they know... (Score:2, Interesting)

    by gr8_phk ( 621180 )

    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?

    • Re:How they know... (Score:5, Informative)

      by sslayer ( 968948 ) on Wednesday December 07, 2011 @11:31AM (#38291108)
      Do you know what happens with practice and theory? In theory, they are both the same. In practice, they are not.

      • Re:How they know... (Score:5, Insightful)

        by nine-times ( 778537 ) <nine.times@gmail.com> on Wednesday December 07, 2011 @11:53AM (#38291396) Homepage
        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.

      • Re: (Score:3, Insightful)

        by TheLink ( 130905 )
        I believe the physical model will experience gravity in one direction, whereas the simulated model doesn't have to?

        • 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.

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

          Does not the Earth also experience gravity in primarily one direction? I hope they built the model so that gravity pulls at 57.5 degrees off the spinning axis.

          • Re: (Score:2)

            by TheLink ( 130905 )

            Does not the Earth also experience gravity in primarily one direction?

            The physical model will have its weight pulling in one direction. The real (and simulated) core won't since it's in the center.

      • "...and you can't just do the math and ignore the fringe effects! With electric motors, it's all fringe effects" (Carnegie Mellon EE professor).

        Real theorists are painfully aware of how their models don't reflect reality, and are careful to say so.

    • 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.)

    • Re:How they know... (Score:5, Insightful)

      by Anonymous Coward on Wednesday December 07, 2011 @11:47AM (#38291332)

      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.

    • Re:How they know... (Score:5, Insightful)

      by JosKarith ( 757063 ) on Wednesday December 07, 2011 @11:58AM (#38291466)
      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.

      • Re:How they know... (Score:4, Insightful)

        by DarkOx ( 621550 ) on Wednesday December 07, 2011 @12:47PM (#38292158) Journal

        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.

        • Well powered flight has immediate and obvious useful applications, this thing less so, at least as far as I can see.

          Understanding the behavior of the earth's core has implications for pretty much all of geology; I hope I don't have to tell you what the "useful applications" of the field as a whole are! By way of analogy to powered flight, what the researchers are doing here isn't so much like the work of the Wright Brothers as it is like the work of Bernoulli and Cayley.

        • 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.
          Actually that would be a pretty dumb thing to do. First of all, I'm sure paper airplanes and other gliders had been pretty well established by then. Next, solid-body wings were quite sensibly rejected on lift vs weight vs strength grounds. All early airplanes used cambered single-surface wings. Now, building a small mode

        • Now you have me thinking that this experiment will lead to us building another Earth in 100 years.

          Too bad we would need more than paper-maché to do that.

    • These models are built on prior experience with given phenomena. They are kept, because up to now, they have successfully predicted physical occurrences to within small margins of error.

      The problem is, we can not be certain of two things
      (1) The model accurately maps the events happening to a mathematical basis, rather than mapping something else entirely, that happens to overlap reality in the cases we've tested.
      (2) There are effects, that in previous tests, have had very minor effect on previous experiment

    • Re: (Score:2)

      by b0bby ( 201198 )

      From TFA:

      No one knows whether this feedback loop will work, says Lathrop, because “there are neither theory nor experiments at these parameters”.

      Enthusiasm for the effort is building beyond Lathrop's group. “Everyone in the community is waiting with bated breath,” says Andrew Jackson, a geophysicist at the Swiss Federal Institute of Technology Zurich. “He's asking questions that we don't know the answer to.”

    • Re: (Score:2)

      by Hentes ( 2461350 )

      To see if the models hold up to an actual experiment.

    • 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.

  • You can get molten sodium at 105C?

  • Inaccurate Model (Score:4, Funny)

    by Mr Bubble ( 14652 ) on Wednesday December 07, 2011 @11:37AM (#38291210)

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

  • Now work can begin... (Score:5, Funny)

    by Saishuuheiki ( 1657565 ) on Wednesday December 07, 2011 @11:37AM (#38291214)

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

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

  • They could let Mythbusters have it when they are done. Take it to a suitable pond (inside a dense metropolitan area the way things are going for them lately), rig it with explosives to open the outer shell, and let all that yummy sodium drop into the water. Make sure several angles of slo-mo are being shot.

    • 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...

  • How can this produce accurate results? (Score:4, Interesting)

    by wisebabo ( 638845 ) on Wednesday December 07, 2011 @11:44AM (#38291288) Journal

    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.

    • Re:How can this produce accurate results? (Score:4, Funny)

      by u38cg ( 607297 ) <calum@callingthetune.co.uk> on Wednesday December 07, 2011 @12:10PM (#38291602) Homepage
      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?

    • Re:How can this produce accurate results? (Score:5, Insightful)

      by athmanb ( 100367 ) on Wednesday December 07, 2011 @12:15PM (#38291690)

      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?

      • Re: (Score:3, Insightful)

        by clickforfreepizza ( 2465094 )

        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

        • 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

          • Re: (Score:2)

            by khallow ( 566160 )

            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.

            That's not the same, since in the case of measurements of neutrinos, they get a speed in excess of the speed of light by one part in 50,000. Given that no other superluminal phenonema have been found and they're dealing with very hard to detect particles at the threshold of measurement for their system, then that tells me that error is likely to be the cause of the measurements.

          • Look guys, sorry if you misconstrued my comments. I honestly don't know why they made an experiment with this design. I was thinking, if they wanted to remove the effects of gravity, shouldn't they do a 2D simulation using a (relatively) thin flat plate of liquid sodium held horizontally? But then I have no clue if this would give any better results. I've heard that 2D supercomputer simulations of exploding supernovas turn out to be completely different (wrong?) from 3D simulations (which are much more

      • I suppose the argument is that physicists were involved? We could replace that one key words and you basically described the whole lobbying process and many people have issues with the way that money is spent:

        A team of [managers] 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?

        I'm not saying the GP was right or wrong, but I had to point out the comparison.

        • I'm not saying the GP was right or wrong, but I had to point out the comparison.

          It's a bad comparison. "By their fruits ye shall know them" -- physicists have a history of producing useful results, managers (as a group) do not. So a reasonable default assumption, in the absence of evidence to the contrary, is that the physicists' plan is basically sound while your hypothetical managers' plan is a load of crap.

    • 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.

      FTFA:

      The experiment will use Earth's natural magnetism as a 'seed field' to kick-start the process. As this field is dragged and stretched by the spinning, conducting liquid it will generate electric currents. Those currents will then create additional magnetic fields that, when sufficiently twisted around, can amplify themselves and drive the process forward.

    • Re:How can this produce accurate results? (Score:5, Insightful)

      by Sockatume ( 732728 ) on Wednesday December 07, 2011 @12:52PM (#38292230)

      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.

    • Re: (Score:2)

      by Hentes ( 2461350 )

      From the article it seems that they aren't building this to be a perfect model of the Earth's core. The question they would like to answer is if it's even possible for heated sodium to generate a magnetic field.

    • Simple: it's not thermal convection driven. The sodium will be nearly isothermal and won't have a density gradient to drive convection.

      But there will be fluid flow that looks like thermal convection. The inner sphere is solid and rotates at a different rate than the outer spherical shell. This will pump fluid from the equator of the inner sphere (like a disk spinning in water, viscous drag will cause it to "throw" fluid outward).

      Then there are the nifty magneto-hydrodynamic stuff they are researching.

    • *Sigh* Lets not bother with fundamental science, even knowing that it is loaded with assumptions and targeting experiments as a starting point for further work, along with modling that can potentially make corrective measures, I mean it's not exactly the way that the Earth works, so it's a bad thing to do. FOR THE LOVE OF PETE! This is exploratory science. It is understood that it is not perfect by a long shot, hell! it may not even have any practical applications (although this does), it may be a complete

    • Re: (Score:3)

      by n3umh ( 876572 )

      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 co

  • Good example of the use of physical models... (Score:3, Interesting)

    by Zrako ( 1306145 ) on Wednesday December 07, 2011 @11:45AM (#38291318)
    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.

  • Yawn (Score:5, Funny)

    by Oswald McWeany ( 2428506 ) on Wednesday December 07, 2011 @11:48AM (#38291338)

    Yawn! Wake me when they have a dual-core earth.

    The single-core model is bound to revolve to slowly!

  • A la Cities In Flight. Cool!!

  • Just starting? (Score:4)

    by Lando ( 9348 ) <lando2+slashNO@SPAMgmail.com> on Wednesday December 07, 2011 @12:11PM (#38291612) Homepage Journal

    Hmmm, knowing that I've seen this before, I decided to go lookabout http://www.popularmechanics.com/technology/engineering/4277476 [popularmechanics.com] 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.

    • Re: (Score:2)

      by Bengie ( 1121981 )

      I was wondering this to and I also recently saw a documentary on Netflix involving a large sodium 3m sphere.

    • Re:Just starting? (Score:5, Informative)

      by schiiz ( 2526742 ) on Wednesday December 07, 2011 @01:25PM (#38292628)
      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.

      • Re: (Score:2)

        by Lando ( 9348 )

        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?

        • Re: (Score:3)

          by n3umh ( 876572 )

          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. Sin

  • Did I read that right? They built this thing for only $2 million dollars!

    Ten years in the making, the US$2-million project is nearly ready for its inaugural run.

    That's incredibly cheap for a project like this. Over the 10 years it took to build, that's only $200k/yr. That's only 2 or 3 salaries, not including materials, and overhead.

    • I think the students worked for free . This was my first thought also. The $200k would barely pay for space and materials.

  • I just want to say I'm really glad that it visibly spins. If it were just a funny looking sphere sitting there that made noises, this would more or less all be for naught. But since it actually spins while it makes noises, you can tell that real science is being done. I'm not saying it couldn't use a few concentric rings, each spinning on its own axis, but this is definitely a step in the right direction.

  • Surely there is a cheaper quicker way to do this?

    In CYC's defense I see no shortcut to AI but I also question the path taken by CYC.

    My bet: neither experiment pans out: both are _eventually_ defunded.

    • How does going out sailing on a boat (in California, Corinthia, Chicago (or any other place starting with the letter C, being home to a yacht club) advance the cause of AI? Also, why do you assume that the 3 m spinning ball of sodium will not produce useful results?

    • Surely there is a cheaper quicker way to do this?

      Maybe you'd like to tell us what it is? Modeling the liquid metal core of the Earth with a sphere of liquid metal seems like a pretty reasonable approach to me. And given the scale of the project, a $2 million price tag doesn't seem particularly high.

  • Sentient bacteria [sciencedaily.com] have constructed a 0.000000708 meter tall model of the model of the earth.

  • ...if it were a life-sized replica...we would have quite a problem on our hands.
  • Why do they need sodium? Why any other conductive liquid is not good enough?

    • Re: (Score:3)

      by n3umh ( 876572 )

      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

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