What is Bose-Einstein condensation? According to quantum mechanical theory, all matter behaves like waves, just like waves on water. For objects with a reasonable mass at ordinary temperatures, the wavelength of these objects is extremely small. This makes it impossible to perceive an object's wavelike properties. But as an object is cooled down to extremely low temperatures, the wavelike nature of the object become prominent.
In our experiment, we cool sodium vapor to extremely cold temperatures and observe its wavelike nature. We start with hot atoms, which bounce around in our atom trap just like little billiard balls. As we lower the temperature, the atoms become de-localized, and their wavelike properties emerge. At even lower temperatures, the wave functions of many atoms overlap each other. They loose their individual identities, and together they form a Bose-Einstein condensate. As we continue to lower the temperature, more and more of the trapped atoms join the Bose condensate.