The Grass is Always Greener Dept - Balls of clay may stick to each other when they collide. This is because the original energy they had before the collision gets so mixed up in heating the clay that the balls have none left to separate. Molecules, particularly small ones, don't generally act this way, since there are not many places for the energy to disappear into. However, Michael Mayle, Brandon Ruzic, and Goulven Quéméner have discovered that at ultralow temperatures, some might actually stick. For example, RbCs molecules (cross section below) may have myriad opportunites to waste energy in rotations and vibrations, rather than in getting away from each other. They should eventually escape this mess, but on time scales long enough to affect the experiment.

Figure. No, we're not working on your lawn again. This is an estimated cross section for scattering of RbCs molecules at ridiculously low collision energies. It is full of resonances, which may enable molecules to stick together for a while. (You may want to water that brown spot, though).

Oil and Water Dept - It is widely known that mixtures of Bose-Einstein condensates (BEC's) can "phase separate" under circumstances where the mutual repulsion of the two BEC's overcomes their self-repulsion. Typically, one BEC goes to one side of the enclosure, and the other goes to the other side. Now, along with Chris Ticknor and Eddy Timmermans, Ryan Wilson has expanded this notion to include dipolar BEC's that possess a roton instability. In this case the separation produces fine patterns like the one shown below.

Figure. Do not adjust your picture. This is an example of the snake-like pattern formed when a dipolar Bose-Einstein condensate (blue) separates itself from a non-dipoalr BEC (black). The way in which this separation happens revelas the "hidden structure" inside the gas.

Will They or Won't They Dep't. Scientists at JILA have recently produced a gas of ultracold molecules. The thing is, these molecules, made of one atom of potassium and one atom of rubidium, react chemically, so they just dissolve out of the experiment. Is this an unavoidable consequence of working with molecules? Or can this pernicious behavior be stopped? Goulven Quéméner shows that, yes it can, by exploitng the right combination of Fermi statistics, confinement in a "pancake" trap, and the natural repulsion that dipolar molecules can feel for one another.

Figure. This is the effective, repulsive potential between two KRb molecules in the JILA experiment, as a function of the frequency v in the tight confinement direction of the pancake trap, and the dipole moment d of the molecules. Increasing the dipole moment helps for a while, as it can make the potential barrier higher and prevent the molecules from getting close together. But for very large dipoles, you need extrmely tight traps, too.