Inventions in sci-fi fall into two main camps: 'could happen' and 'might as well be magic'.
Tractor beams - invisible tethers which pull space ships into cargo bays through no definable mechanism or physical law - are the latter.
Or they were. Researchers at the Australian National University say they have developed what amounts to a tractor beam which is capable of pulling objects using 3D wave currents.
The idea only works in liquids, unfortunately, not the nightmarish wastes of space, but it's very cool. Essentially the team can make waves and currents on demand, and direct boats and objects to specific points without using any on-board engines.
The potential uses included bringing in ships to dock and helping small boats in difficult seas.
So far the team has only made the idea work on a small scale, but it's incredibly neat stuff. Check it out in the video below and head here for more info on how it works.