The idea that a beam emitted from a starship can draw in another object is one of sci-fi's oldest and wildest concepts. It's also slowly becoming a reality. Since 2010, nano-scale tractor beams made up of light particles have been capable of drawing in their tiny nanoparticle prey. A new, acoustic method developed by an international team of scientists has effectively supercharged the nascent technology.
Beams of light and sound function in similar ways, both existing as waves of varying frequency. Imagining them like ocean waves, you might be a bit bewildered as to how waves can tug at you instead of crashing and pushing you away. By making sonic waves strike a target object at just the right angle, however, the research team has found that they can actually create a low pressure zone in front of it, effectively coaxing the object closer with every wavelength. Think of it like manufacturing a sonic undertow.
The use of acoustic wavelengths has improved the effectiveness of existing tractor beams that we can now move objects visible to the naked eye. The size of the objects is still limited to about a centimeter in diameter, meaning that we won't be abducting anybody out of their bed anytime soon. Still, even at today's limited power, doctors are already beginning to eye tractor beams as medical devices. Maybe, as the technology continues to advance, we will someday equip our own starships with real life tractor beams just like those we see in the movies.