Theoretical Physicists Chris Van den Broeck and Ryoichi Kawai are toying with the idea of creating the world's smallest refrigerator. But before you get excited, you'd have to keep in mind that it would take some spectacularly cunning molecular engineering to make the nano device a reality.

The proposed miniature fridge will rely on the random jittering of molecules known as brownian motion, named after the botanist Robert Brown who discovered that bits of pollen under a microscope wouldn't stop jigging around. In general, the faster the molecules move, the higher their temperature. To set the proposal in motion, the mini fridge will use a tiny paddle wheel to speed up the molecules in one pool to suck the energy of a neighboring one. This idea reverses a previous notion about how to use two pools with different temperatures to make a mini motor.

In Van den Broeck and Kawai's model, here's how it works: The two pools start out at the same temperature. Then a motor is used to drive the bottom paddle wheel around counter-clockwise. One principle of thermodynamics says that the system will respond by trying to induce a counteractive force in a clockwise direction. This can happen if the bottom pool gets much hotter than the top one.
The intriguing thing is that the researchers calculate, using standard equations of thermodynamics, that this can not only heat up the bottom pool, but actually cool the top one down.

Making a device to drive a mini wheel around is the tricky part. Lasers or magnets might be used but they're considered borderline of what's feasible. Oh well, they're theoreticians, so they really don't have to bother with reality. So, I guess your nano beers would just have to wait.