In a gas that’s cold enough, the wavelets of matter we call atoms become long and shallow, lose their individuality and blend into one. At least, that’s what happens in a state of matter called a Bose-Einstein condensate. This computer simulation shows a pancake-shaped BEC cloud kept inside an electromagnetic trap and initially (upper left) divided into three parts. Removing the partitions unleashes three matter waves, which collide and interfere with one another (upper right). A honeycomb array of vortices appears for a few milliseconds (bottom left) before the orderly pattern breaks up i...
Credit: Gary Ruben/Monash Univ.

In this simulation of a Bose-Einstein condensate, each vortex rotates in the opposite direction (shown by arrows) as its neighbors, just like a cogwheel rotates clockwise if it’s interlocked with one that’s rotating counterclockwise. Initially observed in experiments, such vortices have been theorized to form from random quantum fluctuations. The new simulation suggests that vortices can form without such fluctuations; instead, they may arise from the interactions of the matter waves, Gary Ruben and his colleagues at Monash University in Australia write in an upcoming Physical Review A. -...
Credit: Gary Ruben’s Lab, Monash University

TOPOLOGICAL HARMONY Familiar relationships between sets of musical notes, such as transposition between chords, directly translate into geometrical structures such as this Möbius strip — where each dot represents a class of equivalent two-note chords — or into more complex structures. MORE
Credit: Science

Flocks of starlings flying over Rome. Physicists used computers to track the motion of single birds in flocks of up to 4,000 starlings. Read the full story.
Credit: STARFLAG Project/INFM-CNR

With computer tracking, physicists found that each starling in a flock adjusts its trajectory to those of its six or seven neighbors, no matter how close or far they are. The technique helps the flocks stay cohesive when attacked by a predator such as a peregrine falcon — although in that case a flock will often still break up into two. Read the full story.
Credit: STARFLAG Project/INFM-CNR

More flocks of starlings’ evening acrobatics — a behavior that may be explained by the need to help other starlings navigate home to their roosting sites after a day spent roaming for food. Read the full story.
Credit: STARFLAG Project/INFM-CNR