Abstract:
Our principal lecturer, Stephen Childress, can be seen emerging
from the "magnetic cottage" he constructed to edify those of us who attended
G.F.D. '87. His central theme was the kinematic properties of the "fast" dynamo,
one whose growth rate is insensitive to electrical conductivity. These novel studies,
and the seminars given by Andrew Soward and others, offer assurance of more mechanistic
understanding of evolving magnetic fields in stars and planets. The timely
juxtaposition of Childress' lectures on kinematic fast dynamos and the seminars by
Bruce Bayly on inertial three-dimensional instabilities of shear flow, may lead soon
to a dynamic fast-fast dynamo.
Faster than convecting continents, slower than Antarctic bottom water, waves
in the Earth's magnetic field move to the west. Geophysicists' knowledge of the
underlying process appears to advance at a similar pace. Yet the dynamos of the
summer season already have suggested hydromagnetic flows which offer hope both
of realizeable laboratory dynamos and more realistic planetary models. Perhaps the
pace of testable predictions will quicken?
