Scientist Proposes Light-Powered Tractor Beam

Hevva

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Scientist Proposes Light-Powered Tractor Beam



This theory could help create the world's first light-powered, ultra-tiny tractor beam.

For as long as fictional spaceships have been roaming the skies of our collective imagination, they've been stopping every now and then to drag objects, people, or space aliens up into their monsterous underbellies using tractor beams. Over the years, various scientists have proposed different methods for making these beams a reality - using heat to manipulate air pressure, for example, or doing the same with magnetic charges - with varying degrees of success. Now a physicist has proposed a novel way to handle the problem: light.

The physicist in question is Mordechai Segev of the Technion-Israel Institute of Technology, who put forward his theory in the journal Optics Express [http://www.opticsinfobase.org/oe/fulltext.cfm?uri=oe-20-8-8907&id=231689#r17]. In his article, Segev postulates that scientists may be able to use the peculiar phenomenon of negative radiation pressure to move objects using refracted light.

Negative radiation pressure occurs when light hits a material that has a negative refraction index, which means that light refracts off of it on the same side as it hits the object rather than anywhere else. Materials that possess such an index are known as "metamaterials," and have been used in the past to create semi-effective invisibility cloaks [http://www.escapistmagazine.com/news/view/99264-Invisibility-Cloak-Might-Actually-Be-Possible]. In cases like the cloak, the metamaterial's negative refraction index effectively re-routes the light that enters it, rendering the object beneath it semi-invisible (well, in theory, at least).

What does this phenomenon have to do with tractor beams, then? Segev's theory goes like this: When light enters a metamaterial, the material's negative refraction index sends its photons barrelling back out in one direction; however, the overall shape of the light waves will be refracted in exactly the opposite direction. According to Segev, when these two groups diverge, we should find a miniscule area of negative radiation pressure between them. If physicists were able to control this negative zone, they might be able to move it - and any particles trapped within - around.

"But wait!" I hear you cry. "All the metamaterials we have are made of metal, and would therefore just absorb the electromagnetic particles essential to this operation, rendering it null and void!" You're right, science fan, that's a problem. Luckily, Segev plans to solve it by implementing quartz and other "birefringent" (something with multiple refraction indices) non-metal materials.

The end result of all this hypothesizing will be a seriously tiny (we're talking micrometers thick) layers of these materials could be manipulated to generate even tinier negative radiation zones between them. Boom! World's first light-powered tractor beam.

As Segev notes, this technology, if it works, will probably be at its most useful in sterile environments where people need to move around tiny objects without undue disturbance. He cites lung surgery, where stable air pressure and gas content are a necessity, as a specific example.

Sadly, we'll have no way of knowing if a negative pressure zone of the kind created by divergent light has the power to hold molecules in its thrall until Segev and his lab complete their tests of his hypothesis. So while this isn't a tractor beam yet - and certainly not one suitable for space-based activities - it is a genuinely interesting step towards practical tractor beam technology. Will further investigation of this theory lead to possible applications outside of the tiny, or will it fall flat in practice?


Source: Wired [http://www.wired.com/wiredscience/2012/06/light-tractor-beams/]







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RvLeshrac

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Awesome, we can theoretically move infinitesimal particles around using a substantially less efficient method than the hundreds of other methods we have for moving infinitesimal particles around.
 

The Rogue Wolf

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RvLeshrac said:
Awesome, we can theoretically move infinitesimal particles around using a substantially less efficient method than the hundreds of other methods we have for moving infinitesimal particles around.
Baby steps. Somebody once said "What do we need an engine for? We have horses."
 

Thaliur

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The Rogue Wolf said:
RvLeshrac said:
Awesome, we can theoretically move infinitesimal particles around using a substantially less efficient method than the hundreds of other methods we have for moving infinitesimal particles around.
Baby steps. Somebody once said "What do we need an engine for? We have horses."
Actually, I was a bit disappointed too. Not about the size, though, that's just a matter of scale, but apparently this is a coating that enables moving things with light, rather than a beam that can move things. Well, maybe someone will figurethat out, too, and one day one of my favourite Farscape conversations (well, one of the several hundreds...) can happen:

John: Pilot, get a tractor beam on that shuttle.
Pilot: Tractor beam? What's that?
John: Graviton field, attracto ray, superglue. Whatever it is you yanked me aboard with.
Pilot: You mean the docking web.
 

RvLeshrac

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The Rogue Wolf said:
RvLeshrac said:
Awesome, we can theoretically move infinitesimal particles around using a substantially less efficient method than the hundreds of other methods we have for moving infinitesimal particles around.
Baby steps. Somebody once said "What do we need an engine for? We have horses."
The engine was substantially more efficient than the horse, and cleaner. The automobile helped remove millions of tons of horse manure, yearly, from our cities.
 

Bvenged

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DVS BSTrD said:
Hevva said:
"But wait!" I hear you cry. "All the metamaterials we have are made of metal, and would therefore just absorb the electromagnetic particles essential to this operation, rendering it null and void!" You're right, science fan, that's a problem. Luckily, Segev plans to solve it by implementing quartz and other "birefringent" (something with multiple refraction indices) non-metal materials.
So there's still a ray of hope?
Yes, there is a light at the end of this tunnel. I bet there are some surgeons and doctors who have read this and are beaming with joy.
 

Able Seacat

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Bvenged said:
DVS BSTrD said:
Hevva said:
"But wait!" I hear you cry. "All the metamaterials we have are made of metal, and would therefore just absorb the electromagnetic particles essential to this operation, rendering it null and void!" You're right, science fan, that's a problem. Luckily, Segev plans to solve it by implementing quartz and other "birefringent" (something with multiple refraction indices) non-metal materials.
So there's still a ray of hope?
Yes, there is a light at the end of this tunnel. I bet there are some surgeons and doctors who have read this and are beaming with joy.
This will be great to pick up chicks... I'll see myself out.
 

Artemicion

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Uh oh. Now Dr. Evil may finally be able to crash "Midas 22" into Earth. With the "tractor beam".
 

VladG

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I'm confused as to how "negative refraction" works.

" which means that light refracts off of it on the same side as it hits the object rather than anywhere else"

EDIT

Right, I looked it up and it's about the angle of refraction, but that still leaves me confused. Instead of the light diverging slightly to one side once it passes the interface, it diverges to the other side.

Extra EDIT

upon looking into it a bit more, I think I get it, the initial light wave basically covers up and hides the negatively refracted ray. Sort of.
 

Bvenged

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Able Seacat said:
Bvenged said:
DVS BSTrD said:
Hevva said:
"But wait!" I hear you cry. "All the metamaterials we have are made of metal, and would therefore just absorb the electromagnetic particles essential to this operation, rendering it null and void!" You're right, science fan, that's a problem. Luckily, Segev plans to solve it by implementing quartz and other "birefringent" (something with multiple refraction indices) non-metal materials.
So there's still a ray of hope?
Yes, there is a light at the end of this tunnel. I bet there are some surgeons and doctors who have read this and are beaming with joy.
This will be great to pick up chicks... I'll see myself out.
If you're struggling to have a light-bulb moment, it's cool. Today I'm having a shining moment, but we can't all be bright all of the time.
 

sorsa

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Dec 19, 2011
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Wait.. the aliens were supposed to come up with this first. This is going all wrong.. are we supposed to build the flying saucers too? Next thing we know humanity takes to the stars, abducting aliens and violently collecting rectal samples with modified dildo-probes, we were supposed to be the good guys. :(