tractor beam
A tractor beam is a hypothetical beam, familiar from science fiction, that can attract or move objects from a distance. In UFO literature it appears as an alleged capability of UFOs, mainly in abduction stories; in physics, only microscopic-scale counterparts are known.
A tractor beam is an imaginary or experimental device that moves, attracts or holds an object from a distance by means of a light beam, an energy beam or some other physical effect. The term was coined in 1931 by the American science fiction writer E. E. "Doc" Smith in his novel Spacehounds of IPC, and it later spread through science fiction films and series, where it is mostly used by spacecraft to capture one another or to lift cargo.
In UFO literature
Some eyewitnesses and UFO researchers describe a beam of light directed from the alleged craft toward the ground, by means of which vehicles, animals or people were lifted or moved. A light that pulls upward is a common element in abduction stories. One of the best-known examples is Travis Walton's 1975 case in Arizona: according to Walton, a beam of light struck him, and his next memory was already set aboard the craft. These descriptions are personal accounts; no physical evidence supports them.
Scientific background
Physics knows of methods by which small objects can be moved from a distance without contact. Optical tweezers use a tightly focused laser beam to grab and move microscopic particles, even living cells; Arthur Ashkin received the Nobel Prize in Physics in 2018 for developing them. In 2014, researchers at the Australian National University used a donut-shaped laser beam to move gold-coated glass spheres about 0.2 millimeters in size over distances of up to 20 centimeters, both forward and backward. Here the effect was caused not directly by the light but by the heating of the particle and the air streaming out around it. In 2015, researchers at the University of Bristol and the University of Sussex used a device made up of 64 tiny loudspeakers to lift, move and rotate small objects with an "acoustic hologram" created by high-intensity sound.
These methods currently work only at a microscopic or very small scale and over short distances. No device is known that is capable of moving everyday-sized objects, cars or people from a great distance, and based on physics as currently known, such a device would require an astonishing amount of energy.
Skeptical view
There is no official position on tractor beams, and there is no documented case in which a device of unknown origin has been proven to have used a tractor beam. Skeptical researchers mostly explain the accounts as misinterpreted phenomena. A common natural cause of vertical beams of light reaching from the sky to the ground is the light pillar: in cold weather, lights on the ground reflect off tiny ice crystals suspended in the air and appear as vertical columns. A helicopter's searchlight produces a similar sight. In the case of abduction accounts, the most common explanations are memory distortion, sleep paralysis and the influence of the imagery of popular culture.
Sources
- Nobel Prize: Arthur Ashkin – fizikai Nobel-díj 2018
- Sci.News: Scientists Build „Long-Distance” Optical Tractor Beam (2014)
- University of Bristol: From science fiction to reality – sonic tractor beam invented (2015. október 27.)