The coldest stuff in the universe floats in a glass tube no bigger than a man's index finger, half-hidden amid a dizzying tabletop array of lenses, mirrors, magnetic coils, and lasers. Inside the tube, the temperature checks out at a mind-numbing three nanokelvin above absolute zero - more than a billion times colder than the icy emptiness of interstellar space. Suspended by magnets in their icy prison, a few thousand atoms of silvery rubidium gas are acting very strangely. Instead of whizzing around and colliding with each other at random, like atoms in a normal gas, the ultracold rubidium atoms are behaving like well-drilled soldiers, all lined up and moving as if they were a single atom. Which, in a sense, they are - thanks to a phenomenon called Bose-Einstein condensation, the subject of this year's Nobel Prize in physics.