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Hank tells us about some developments that are being made in the dramatic area of laser tractor beams.

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Thank goodness, finally, NASA is starting to take some tips from Darth Vader.

And why wouldn't they? I've been taking tips from Darth Vader all my life. It's how I learned to make people gag without touching them. Thankfully they're not trying to explode entire planets; they're trying to create a tractor beam.

Late in 2011 NASA announced that they were developing technologies to harness objects with lasers. The point of this, however, is not to capture the Millennium falcon or whatever; it's to use these laser beams to pull in particles from the tail of a comet or from the upper atmosphere of a planet without getting so close that you get all caught up in the drama of that thing's gravitational pull.

The fact is, we actually already know how to capture stuff and move it around with beams of light. So we all know that light behaves both like a wave and like a particle and those particles, which really are more light packets are called photons. Photons can work a little bit like quantum billiard balls. You can shoot them at an object and they'll knock into it and actually give it a little push. That's the concept behind this hot little concept, the optical tweezers.

Starting in the 1980s scientists have been able to trap particles with lasers and then sort of slap them around with photons. They are now tons of different types of optical tweezers.

The simplest version involves shooting a laser at this this relatively large translucent particle. As photons refract through that particle, it kicks it at a slight angle. Multiple lasers from multiple angles are refracted through and they basically kick back against each other holding that particle in a very specific place.

Scientists are using this technology to study DNA, and viruses, and bacteria. So we can freeze, and even push particles with light, but pulling particles, now that turns out to be a much more difficult problem.

The first possible solution to this fairly difficult problem involves using lasers whose energies take different shapes. Typically, a laser beam is most intense at its center, but with one kind, called a solenoid beam, the highest intensity forms a spiral around the center of the beam. In lab experiments, photons sent at an angle through this corkscrew of energy succeeded in attracting tiny particles and kicking them back toward the source of the light. And there are some other tractor beam ideas out there, but they are so far totally theoretical and they involve using some other properties of light, including its electromagnetic field, to alter the polarity of particles isolated by overlapping beams and then use that polarity to draw them toward the source of the beams.

If you don't quite get it, don't feel bad, 'cause neither do I, and neither does NASA. That's why they're dropping 100 grand on some geniuses at the Goddard spaceflight center in Maryland to connect the dots for them. And you've probably by now noticed that we're only talking about tractor beams moving very small particles - well thanks for pointing that out, yeh, it's not as exciting as Star Trek or Star Wars. NASA originally was interested in using tractor beams to help clean up space junk which we have a lot of, floating around up there now. But the technology is just not feasible yet. So it's dead, we're just gonna have to use the technology to make cool new discoveries. And when that happens, don't forget, hat tip to Lord Vader.

Thank you for watching this episode of SciShow. Our references, of course, are in the description because we're good little scientists. You can connect with us on Facebook and Twitter, if you would like to uh ask us questions or suggest ideas for new SciShow episodes, and of course we'll be in the comments below.

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