"Invisibility shields will become a reality": U of Penn scientists

[jay gw]

The cloaking device, famously used by the Romulans in Star Trek to hide their spacecraft from enemies, may yet become reality, thanks to US researchers.

University of Pennsylvania PhD student Andrea Alu and professor Nader Engheta have written a paper for the journal Nature describing how a crude cloaking device could be built.

Mr Alu and Professor Engheta say their "plasmonic cover" could render objects "nearly invisible to an observer".

So far, research into invisibility has concentrated on camouflage: a screen is coloured to match its background, for example. But the invisibility shield proposed by the two researchers is more ambitious - a "self-contained structure that would reduce visibility from all viewing angles", according to Nature.

"We see objects because light bounces off them; if this scattering of light could be prevented (and if the objects didn't absorb any light) they would become invisible. [The] plasmonic screen suppresses scattering by resonating in tune with the [frequency of the] illuminating light," they say.

Plasmons are waves of electron density, caused when the electrons on the surface of a metallic material move in rhythm. For visible light, such plasmonic materials include silver and gold.

The calculations show that spherical or cylindrical objects coated with the shields scatter little light. "When lit by light of the right wavelength, the objects become extremely small, so small they cannot be seen," according to Nature.

The journal also says the shielding "would work fine for concealing large objects such as spaceships from sensors or telescopes that used long-wavelength radiation instead of visible light."

http://tinyurl.com/3lwha

Fascinating. I hope they pursue this research, the applications are numerous.

[Bodhi Dharma Zen]

Extremely nice, but I wonder if this would be just "vaporware" for ages...

[Dymanic]

One scheme I remember seeing discussed involved collecting light from one side of an object, chanelling it to the other side through fiber optic strands, and sending it on its way. I don't see why it couldn't work. In fact, while we're at it, we might blend in some digitally-created stuff on the fly, so the bad guys not only couldn't see what was there, they'd see stuff that wasn't.

[Ashles]

Originally posted by Dymanic
One scheme I remember seeing discussed involved collecting light from one side of an object, chanelling it to the other side through fiber optic strands, and sending it on its way. I don't see why it couldn't work. In fact, while we're at it, we might blend in some digitally-created stuff on the fly, so the bad guys not only couldn't see what was there, they'd see stuff that wasn't.
But all these 'project from one side what's on the other' ideas have the same problem that the same fiber optic strand/photocell/etc. can't show different colours to people standing in different places.

I just fan't see how any of this would work practically.

And the whole plasmon field thing... well I'll believe it when I, er, don't see it.

[CurtC]

Originally posted by jay gw
The calculations show that spherical or cylindrical objects coated with the shields scatter little light. "When lit by light of the right wavelength, the objects become extremely small, so small they cannot be seen," according to Nature.
I don't understand this - are we approaching April 1 again? If an object doesn't scatter light, wouldn't it just look black? What does that have to do with its becoming small? You still have the fundamental problem that the light from an object on the other side of this "thing" will have to pass through unimpeded, no matter whether its surface scatters light or absorbs it.

[aofl]

Originally posted by jay gw
Mr Alu and Professor Engheta say their "plasmonic cover" could render objects "nearly invisible to an observer".

"Plasmonic Cover"? This sounds like something out of Dr Who. I bet if they reverse the polarity of the neutron flow they can actually make the object look larger.

A

[RussDill]

Originally posted by CurtC
I don't understand this - are we approaching April 1 again? If an object doesn't scatter light, wouldn't it just look black? What does that have to do with its becoming small? You still have the fundamental problem that the light from an object on the other side of this "thing" will have to pass through unimpeded, no matter whether its surface scatters light or absorbs it.

I think they are going to make it perfectly shiney, like a mirror. My opinion, such a technique could work, but you need to change the absorbtion on different parts of the mirror based on the direction of viewing angle, and what is on the other side of the object, both I think, would be possible.

[69dodge]

The OP left out the catches:
However, there are a couple of catches. The first is that a shield only works for one specific wavelength of light. An object might be made invisible in red light, for example, but not multiwavelength daylight.

The second catch is the effect only works when the wavelength of the light scattered is roughly the same size as the object.

So shielding from visible light is only possible for microscopic objects, not people or spaceships.

[neutrino_cannon]

LOL!

Wait, are they saying cover a lot of big, spherical objects in the little invisible ones?

And finally, wasn't there the Japanese engineer who worked out a way to use spherical retroreflectors and active projection of light to achieve some degree of invisibilty?

[Brian the Snail]

If anybody is interested, I'm selling invisibility devices at $9999.99 each. Guaranteed to be completely invisible, or your money back. Just to prove that this is legit, here's a picture of the prototype:

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[Darat]

Paint it pink and make it someone else’s problem..

I do wonder if this is going to appear in the April edition of Nature?

[BillHoyt]

I'm always leery of claims shot over the starboard bow around about April, but you may want to google "plasmonic" a bit before dismissing it. For instance, here's something very suggestive. (http://www.csulb.edu/~mbarbic/plasnano.htm)

[hgc]

Originally posted by Dymanic
One scheme I remember seeing discussed involved collecting light from one side of an object, chanelling it to the other side through fiber optic strands, and sending it on its way. I don't see why it couldn't work. In fact, while we're at it, we might blend in some digitally-created stuff on the fly, so the bad guys not only couldn't see what was there, they'd see stuff that wasn't. Q fixed up a BMW for 007 that does this. He used it outside an ice palace hotel in Greenland or somesuch cold-ass place. That ice palace hotel was totally ridiculous.

[Rolfe]

Originally posted by hgc
That ice palace hotel was totally ridiculous. Except it was real, or was based on a real construction. Amazing what you find out when you listen to the commentary tracks on the DVDs!

Rolfe.

[Darat]

And all the gadgets on the Jaguar were real, all available as options in the "Villian Pack".

[LW]

Originally posted by hgc
He used it outside an ice palace hotel in Greenland or somesuch cold-ass place. That ice palace hotel was totally ridiculous.

I don't have any idea on what Bond you are talking about, but there is an annually-rebuilt ice castle in Kemi, Finland that operates as hotel and restaurant every winter. This winter it was opened on 31.12. and it is scheduled to stay open until beginning of April, weather permitting.

The URL [url}http://www.snowcastle.net[/url] may have some English information but as the pages are incompetently made I found only Finnish stuff.

[Soapy Sam]

The human eye / brain is very good at identifying visual patterns and anomalies. Visually detecting an invisible man would be pretty easy, I suspect, especially if he moved.

The best way to conceal something is to put it where nobody looks.

It's behind you...

[Ashles]

Originally posted by Rolfe
Except it was real, or was based on a real construction. Amazing what you find out when you listen to the commentary tracks on the DVDs!

Rolfe.
I've been to the ice hotel and it's a damn sight different to the colossal elaborate palace in the Bond film.

Real ice buildings look like you might imagine: blocky and of one, possibly occasionally 2 stories. Bond baddies can build Liechtenstein like structures.

[Dragon]

As Q would say - "Please try and keep up."

It was Iceland, not Greenland.
Bond's car was an Aston Martin, the villain with the diamond-studded face had a Jag.

Back OT -
I'm sure I read somewhere that the military are actively researching this, as you'd expect.

I think Version 1 will just present the same colours, tones and lighting from behind the tank, or whatever, to the observer. Should prove effective for a static vehicle against something like a wooded background.
IIRC light-emitting polymers are the favoured way of acheiving the effect. No time to Google at the moment, might try later.

[Ashles]

Originally posted by Dragon
I'm sure I read somewhere that the military are actively researching this, as you'd expect.
Yeah, but haven't the military researched remote viewing and staring at goats to stop their hearts?

The military's involvement is hardly a certificate of legitimate research. :)

[DangerousBeliefs]

The future is now (http://www.8bm.com/diatribes/volume02/diatribes002/diatribes21-41/diatribes39.htm) and now... (http://www.nasatech.com/Briefs/Aug00/NPO20706.html)

I'm willing to bet the military already is working on something much better than this stuff.

[jay gw]

The idea is that if the object is stationary, it would project what is behind it, right? Take the image from behind it, and then project it in front of it.

So, if you stared at it, you would see thru it. Or so you think.

I can see one application for this: spy cameras in obvious and public places. If you didn't know it was there, you would do things you wouldn't ordinarily do. Any kind of sensor may need to be disguised.

If a special forces type needs to get in close, they could use something like it. As long as the camera/projector has something to project in front of it, and you are absolutely motionless it would work.

Taking advantage of any shadows or using it at night would require someone with very good eyes to spot you.

[Soapy Sam]

If a special forces type needs to get close, he looks like your neighbour, turns up on Saturday morning when you're busy and carries a kitchen knife in a plain brown envelope.