A “tractor beam” is a science-fiction term that refers to a device capable of pulling in distant objects without any physical contact.
As any true Star Wars fan could tell you, the Death Star was equipped with hundreds of tractor beam generators that were used to seize and capture ships like Han Solo’s Millennium Falcon. But even those who are not quite geeky enough to get those references will still be amazed to know that scientists have now created a real-life sonic tractor beam that can be used to hold, move, and even rotate small objects completely without touch.
The concept of the tractor beam stretches back long before Star Wars. Short for “attractor beam,” the science fiction writer E.E. Smith first coined the term in his 1931 novel Spacehounds of IPC. In addition to Star Wars, the television show Star Trek was responsible for popularizing and solidifying the idea as part of popular culture. In it, tractor beams were routinely used by starships and space stations to tow in smaller crafts that were either inert or in trouble. Since then, tractor beams have pervaded mainstream media, getting referenced by non-sci-fi films such as the Austin Powers franchise, Dumb and Dumber, and Wayne’s World. Some of us might delight in remembering when Garth warns Wayne saying, “Stacy alert. We’ve been spotted and are being pulled in by her tractor beams.”
Whereas in Star Trek, tractor beams appeared as shimmering rays of light, those in Star Wars were invisible. The real-life version has more in common with the latter, as scientists from the Universities of Bristol and Sussex, in collaboration with Ultrahaptics, have used pure sound to control objects.
The study, published in the journal Nature Communications, describes how the team of researchers was able to create the first sonic tractor beam using 64 miniature speakers to generate high-intensity sound waves. These waves work by—get this—creating an acoustic hologram, which acts as a bona fide force field that can manipulate multiple objects in mid-air. Sounds pretty badass, right? The technique is a perfect example of how quickly our technology is beginning to blur the lines between science fiction and reality.
However, this isn’t the only tractor beam to be invented by physicists. Just last year, lasers were used to create the first long-distance optical tractor beam, which was able to move particles a fifth of a millimeter in diameter across a distance of almost 8 inches. However, the sonic tractor beams of this most recent study reeled in spherical beads about 10 times that size, albeit from a shorter distance away. One significant advantage of sonic beams over light-based ones is that it can do a lot more manipulations than just pushing and pulling. The scientists were able to position the high-amplitude sound waves in ways that created three different shapes of tractor beam force fields: one shaped like a pair of tweezers, another like a cage that surrounds and holds objects, and also a vortex that traps them in its center.
Beyond just being a really neat phenomenon, there are very practical real-world applications for sonic tractor beams. In the past, acoustic force fields that could control particles required speakers that surrounded the object. These new sonic tractor beams use a single beam, allowing a device that is placed on the skin’s surface to manipulate particles inside the body. In this way, things like drug capsules, kidney stones, or microsurgical instruments can be maneuvered with a high degree of precision. Additionally, sonic tractor beams could be used to assemble delicate objects that are too fragile to be touched.
As impressive as all this is to the scientific community, it is certain that some technology-spoiled members of society won’t be as satisfied with the findings. Moving small beads less than an arm’s length is nothing close to the tractor beams we’ve encountered in our favorite sci-fi stories. To those naysayers, I can only give you the same advice that Obi-Wan Kenobi gave to Luke Skywalker when Luke wanted to stop his training to go fight before he was ready: “Patience!”
According to the lead author of the study, Asier Marzo, their team has more ambitious plans for the future. At the moment, they are designing different variations of the system, such as “a bigger version with a different working principle that aims to levitate a soccer ball from over 30 feet away.” Holy crap, that is cool. And if we can soon expect sonic beams that can do all that, who knows what can be achieved in the next few decades. Maybe we will see tractor beams that can pull in small aircraft over long distances, and—just maybe—some lucky Star Wars geek will be behind the controls, living out his ultimate nerd fantasy.