Non-scientists can introduce themselves to the concept of symmetry-breaking by reading this newly published study by Creppy and colleagues:
“Symmetry-breaking phase transitions in highly concentrated semen,” Adama Creppy, Franck Plouraboué, Olivier Praud, Xavier Druart, Sébastien Cazin, Hui Yu, Pierre Degond, Journal of the Royal Society Interface, epub October 12, 2016. The authors write:
Depositing fresh semen sample in an annular shaped microfluidic chip leads to a spontaneous vortex state of the fluid at sufficiently large sperm concentration. The rotation occurs unpredictably clockwise or counterclockwise and is robust and stable. Furthermore, for highly active and concentrated semen, richer dynamics can occur such as self-sustained or damped rotation oscillations. Experimental results obtained with systematic dilution provide a clear evidence of a phase transition towards collective motion associated with local alignment of spermatozoa akin to the Vicsek model.
Here’s further detail from the study:
(Thanks to Bob O’Hara for bringing this to our attention.)