The quest for the most spherical bubble

This study tells of progress in the quest for the most spherical bubble:

The quest for the most spherical bubble: experimental setup and data overview,” Danail Obreschkow, Marc Tinguely, Nicolas Dorsaz, Philippe Kobel, Aurele de Bosset, Mohamed Farhat, Experiments in Fluids, April 2013, 54:1503. (Thanks to investigator Tom Gill for bringing this to our attention.) The authors, at the University of Western Australia, Laboratoire des Machines Hydrauliques in Lausanne, Switzerland, and the University of Cambridge, UK, report:

“We describe a recently realized experiment producing the most spherical cavitation bubbles today. The bubbles grow inside a liquid from a point plasma generated by a nanosecond laser pulse. Unlike in previous studies, the laser is focussed by a parabolic mirror, resulting in a plasma of unprecedented symmetry. “

BONUS: “Pearls And The Puzzle of How They Form Perfect Spheres“, in the arXiv blog, about this study:

Pearls Are Self-Organized Natural Ratchets,” Julyan H. E. Cartwright, Antonio G. Checa, Marthe Rousseau, arXiv:1304.3704v1, April 12, 2013. The authors, at the Universidad de Granada, Spain, report: “Pearls, the most flawless and highly prized of them, are perhaps the most perfectly spherical macroscopic bodies in the biological world. How are they so round? Why are other pearls solids of revolution (off-round, drop, ringed), and yet others have no symmetry (baroque)? We find that with a spherical pearl the growth fronts of nacre are spirals and target patterns distributed across its surface, and this is true for a baroque pearl, too, but that in pearls with rotational symmetry spirals and target patterns are found only in the vicinity of the poles; elsewhere the growth fronts are arrayed in ratchet fashion around the equator. We demonstrate that pearl rotation is a self-organized phenomenon caused and sustained by physical forces from the growth fronts, and that rotating pearls are a – perhaps unique – example of a natural ratchet.”