abstract
| - In 1905, shortly after composing his special relativity paper, Albert Einstein described the origin of the Earth's magnetic field as being one of the great unsolved problems facing modern physicists. Since then, there have been many studies of the geodynamo problem based on historical measurements of the Earth's field. In order to maintain the magnetic field against ohmic decay (which would occur for the dipole field in 20 kyr) the outer core must be convecting. Convection is likely some combination of thermal and compositional convection. The mantle controls the rate at which heat is extracted from the core. Heat sources include gravitational energy released by the compression of the core, gravitational energy released by the rejection of light elements (probably sulphur, oxygen, or silicon) at the inner core boundary as it grows, latent heat of crystallization at the inner core boundary, and radioactivity of potassium, uranium and thorium.
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