Some Provocative Unresolved Problems in Rayleigh-Benard Convection: Guenter Ahlers, University of California, Santa Barbara

This talk will address a number of experimental observations or measurements pertaining to pattern formation in Rayleigh-B\'enard convection (RBC) which fall into one or both of the following categories:

1.) They seem interesting but have never been addressed theoretically

2.) They disagree with theoretical predictions.

Included are:

a.) the re-emergence of relatively simple patterns in cylindrical samples at large Rayleigh numbers

b.) Unorthodox correlation-length scaling and defect formation in domain chaos, i.e. in RBC with rotation

c.) Formation of "squares" where K\"uppers-Lortz-unstable rolls are predicted in RBC with rotation

d.) A subcritical bifurcation without hysteresis in RBC with rotation

e.) Absence of convection above a predicted Hopf bifurcation in RBC with rotation