Tractor beams, from Star Trek to Star Wars to Babylon 5, have always been quite direct things. A beam fires out from one spaceship directly towards another, and ship two moves towards ship one. Simples.
Turns out, it’s not like that. Apparently it needs to hit at a very specific angle to work. Yes, someone has come up with something that may work as a tractor beam. Most awesome.
A laser can act as a “tractor beam”, drawing small objects back toward the laser’s source, scientists have said.
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The trick is not to use a standard laser beam, but rather one known as a Bessel beam, that has a precise pattern of peaks and troughs in its intensity.
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If such a Bessel beam were to encounter an object not head-on but at a glancing angle, the backward force can be stimulated.As the atoms or molecules of the target absorb and re-radiate the incoming light, the fraction re-radiated forward along the beam direction can interfere and give the object a “push” back toward the source.
Sure, it’s not going to shift a multimegaton space freighter anywhere anytime soon, but it’s a promising start. I look forward to the day when you can see AA trucks moving about the place because of their strangely pointing laser beams…