Mantle rock motion is about one million times slower than the motions of the outer core. Sinking, cold mantle material spreads into blobs when it reaches the core and shoves aside hot material at the boundary. The resulting cold patches, which remain for hundreds of millions of years, pull heat more rapidly from the core and seem to affect the magnetic field's evolution. This uneven heat exchange has features too small for current supercomputers to mimic when treating the whole globe, so Olson uses simulation of a different sort. With an attached shaft, postdoc Ikuro Sumita spins the bowl at 250 revolutions per minute to approximate the Earth's rotation and gravity.
Wires inject appropriate hot and cold patterns from the mantle and inner core.
As the apparatus revs up, green-dyed water portraying molten iron rolls around inside the bowl. A parade of spirals soon join in a pinwheel. Eventually, the dye drifts westward. Olson smiles because observations show the Earth's magnetic field does that. Likewise, temperature probes on the bowl confirm a measured large heat loss around the Pacific Ocean.