Some clusters of very cold atoms have physicists foxed, the American Physical Society's March meeting heard this week in Seattle.
Ordinary matter comes in five forms.
The fourth, plasmas, are found in high-temperature systems such as flames and fluorescent tubes. Christened in honour of Albert Einstein, who postulated their existence in 1924 based on the work of Satyendra Bose, the first BECs were produced by Eric Cornell and Carl Wieman at the University of Colorado in 1995. Even so, they fascinate physicists keen to deepen their understanding of quantum phenomena. Eventually, the wavefunctions from neighbouring atoms overlap and the whole condensate starts to behave as a single quantum-mechanical object. Nonetheless, the new technique gave researchers a tool rather like a pair of magnetic pliers to manipulate the condensates.