The 3-metre-tall ribbed sphere looks like a 'visitor' from another planet, dramatically lit and encased within a sturdy steel box. In fact, the giant orb, housed in a cavernous warehouse at the University of Maryland, College Park, is meant to approximate Earth's core.
Ten years in the making, the US$2-million project is nearly ready for its inaugural run. Early next year, the sphere will begin whirling around while loaded with 13,000 kilograms of molten sodium heated to around 105 °C. Researchers hope that the churning, electrically conducting fluid 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. If it works, it will be the first time that an experiment that mirrors the configuration of Earth's interior has managed to recreate such a phenomenon.
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“Dynamos are easy to generate in nature,” says project leader and experimental geophysicist Daniel Lathrop. “The same is not true for the lab.” Yet simulating this process in the laboratory will guide our understanding of processes that take place 3,000 kilometres below ground, at depths that can be probed only indirectly — by analysing seismic waves that have travelled through Earth's deep interior, for example.
“There's no way for us to measure anything near the core directly,” says Lathrop. “It exceeds the deepest well by a factor of 100.”
The University of Maryland set-up consists of two concentric spheres (see ‘Recreating Earth’s core in the lab’). The inner sphere, at 1 metre across, stands in for Earth's solid inner core; the outer sphere the edge of Earth's mantle. The space between the two is filled with liquid sodium, mimicking the liquid outer core. Each sphere is powered by a separate motor so that it can rotate independently of the other. By spinning the spheres across a range of matched and unmatched velocities — up to 4 revolutions per second for the outer sphere and 12 for the inner — Lathrop and his team will study how heat and rotation might affect the movement of the molten iron in Earth's core.
But the question that looms largest is whether the churning sodium will mimic the geodynamo and generate a self-perpetuating magnetic field. 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. No one knows whether this feedback loop will work, says Lathrop, because “there are neither theory nor experiments at these parameters”
Pretty cool experiment. It will be interesting to see what comes out of it!
Sabre (Julian) 92.5% Stock 04 STI
Good choice putting $4,000 rims on your 1990 Honda Civic. That's like Betty White going out and getting her tits done.
The “georeactor” hypothesis is a proposal by J. Marvin Herndon that a fissioning critical mass of uranium may exist at the Earth’s core and indeed that it serves as the energy source for the Earth’s magnetic field. You can read all about Herndon’s ideas at his website.
Herndon’s georeactor hypothesis is not widely accepted at all by the scientific community, outside of Herndon himself and a very small number of defenders.
Herndon’s georeactor hypothesis is sometimes confused with the existence of natural nuclear fission reactors in the Earth’s crust in rich uranium deposits at Oklo in Western Africa – however, it must be stressed that these are not the same thing – there is absolutely no doubt at all, scientifically, as to the occurrence of nuclear fission and the formation of natural nuclear “reactors” at Oklo approximately two billion years ago.
The kook has an appropriately kooky and 1997-web-design-in-vi look.
