Why geomagnetic reversals resist prediction
PAPER III — PHYSICS · QUESTION 35 OF 35
In plain terms: The free official archive of the Earth’s magnetic field and its recorded flips.
The question as set
The geodynamo has reversed the field hundreds of times without periodicity. State what a working dynamo requires, and say why the reversal statistics resist prediction rather than merely resisting measurement.
The question in Paper III · Its section on the reference page
The question in context
This is question 35 of the 35 set in Paper III — Physics of The Truly Hardest Exam in the World, the examination of The College of All Minds. In the College’s subject index it is filed under Climate and the Earth system and Seismology and the Earth’s interior. Like every question of the College, it carries three references of record, verified live at publication and described twice — technically, and in plain terms — so the ground can be judged before it is walked. The response required is an argument, not a survey, of at most three thousand words, as technical as the question demands and no more.
The references of record
Geomagnetism — the national data record
The observational record: field models, secular variation, and the palaeomagnetic reversal chronology.
In plain terms: The free official archive of the Earth’s magnetic field and its recorded flips.
The dynamo condition stated: magnetic Reynolds number, convection and rotation, with reversals emerging from the same equations that sustain the field.
In plain terms: A free review of how the numerical dynamos work, and why their reversals arrive without a schedule.
The current literature on reversal statistics, chron durations, and the case against periodicity.
In plain terms: The standing index to new work on why the reversals cannot be forecast.
Background: Geomagnetic reversal · Dynamo theory