Threshold Crossed on the Way to a Geodynamo in a Computer

摘要

How do you tell whether you've got the right answer if you never get to look at the answer sheet? Geophysicists trying to conjure up the geodynamo that generates Earth's magnetic field have been grappling with that conundrum for years. Seemingly any computer model with the basic physics of the churning molten-iron core produces a reasonable-looking magnetic field as seen at Earth's surface. Yet the models produce those similar surface fields by creating entirely different geodynamos in their cores (Science, 10 January 1997, p. 160). Without access to the real core, how do you tell which one is right?