One of the larger mysteries of physics currently is likely the barrier between classical and quantum mechanics. At some point the rules change and discovering that point could allow us to eventually understand how the world we live in arises from the quantum world. Researchers at McGill University, the University of Vermont, and Leipzig University have recently performed an experiment that should help uncover the transition point.
Superfluid is a curious state a matter that is currently only known to exist for very cold liquid helium. In this state, the liquid flows without viscosity, which allows it to do some weird things, like move through small pores normal fluids could not. Normal fluids will also speed up as they travel through a small channel, like a river through rapids, but according to the Tomonaga-Luttinger theory, a superfluid will actually slow down if the pore size is small enough. It took a pore size less than 30 atoms wide, but the researchers finally observed such a slowdown.
It took a long time and an accident to finally make this experiment happens, as cutting the pores required using an electron beam and only after a student left a valve open during a run did they solve a problem with containments. Now that the nano-faucet is working though, it could be applied to help explore the region between quantum and classical mechanics, by observing behaviors at pores of different sizes. It could also be used to develop advanced nano-sensors.