Slashdot Log In
How To Cloak Objects At a Distance
Posted by
samzenpus
on Thu Nov 06, 2008 07:57 AM
from the can-you-see-me-now dept.
from the can-you-see-me-now dept.
KentuckyFC writes "All invisibility cloaks to date work by hiding an object embedded inside them. Now a group of physicists have worked out how to remotely cloak objects that sit outside a cloaking material. The trick is to make the cloaking material with optical properties that are exactly complementary to the space outside them. Complementary means that the material reverses the effect the space has on a plane wave of light passing through it. To an observer this space would appear to vanish. The scientists say that to cloak an object sitting outside the cloaking material, first measure its optical properties and then embed a "complementary image" of the object within the cloak. So a plane wave is first distorted by the object but then restored to a plane by the complementary image of the object within the cloak (abstract). An observer sees nothing. This method has another benefit. Objects hidden in conventional cloaks are blinded because no light enters the cloaked region. But objects that are remotely cloaked like this should still be able to see their surroundings."
Related Stories
[+]
Technology: Illusion Cloak Makes One Object Look Like Another 219 comments
KentuckyFC writes "Metamaterials are synthetic substances that can steer light in any way imaginable. Their most famous incarnation is in invisibility cloaks which work by steering light around a region of space making any object inside that region invisible. But invisibility is just the start. A team of physicists in Hong Kong (the same guys who recently worked out how to cloak objects at a distance) have worked out how to create a cloak that makes one object look like another. Instead of steering light to make a region of space look empty, the illusion cloak manipulates light in a way that makes a region of space look as if it contains a specific object. So any object within that region of space, a mouse say, takes on the appearance of an elephant."
[+]
Big Bang Could Be Recreated Inside a Metamaterial 113 comments
KentuckyFC writes "Metamaterials are substances with a permittivity and permeability that has been manipulated in a way that allows fine control over the behavior of light. They have famously been used to create an invisibility cloak that hides objects from view. Now Igor Smolyaninov, a physicist in the US, has calculated how metamaterials could be used for a much more profound demonstration: to reproduce the behavior of light in various kinds of spacetimes, in particular a (2+2) spacetime (one having two dimensions of space and two of time). His method is to show that there is formal mathematical analogy between the way metamaterials and spacetimes affect light. He goes on to show how a phase transition in a (2+2) spacetime leads to the creation of a (2+1) spacetime filled with photons, an event analogous to the Big Bang." Here are the abstract and the preprint (PDF).
[+]
How To See Through an Invisibility Cloak 201 comments
AMESN writes "Ways to bend light around objects and render them invisible are becoming a major field of scientific study and gaining ground. While no actual invisibility cloak exists yet, researchers are also theorizing on how to beat the perfect cloak."
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Full
Abbreviated
Hidden
Loading... please wait.
Wow smart scientists... (Score:5, Funny)
"The trick is to make the cloaking material with optical properties that are exactly complementary to the space outside them. "
So if you are hiding a tank in the desert, paint it desert colors?
Oh wait more complex... desert != shiny...
use flat paint.
got it!
Re:Wow smart scientists... (Score:5, Funny)
So if you are hiding a tank in the desert, paint it desert colors?
We've actually gone one step further. We've actually built an entire tank made out of sand. Our prototype required very little materials other than that: a bucket, a shovel and a beach.
It's still a prototype though since it breaks easily, but it does blend in with its surroundings, and it has been proven combat worthy by having our troops stomp over sandcastles.
Parent
Re: (Score:2)
What do you mean prototype? that sounds almost ready for serious use - just look at most tanks ;)
Re:Wow smart scientists... (Score:5, Funny)
Heh, you know to this day I'm still pissed about something that happened when I was in 2nd grade. We were doing some kind of group work thing and I got was this multiple choice question about what a telescope could be made out of. One of the possible answers was sand. I instantly came up with the design in my head. The question wasn't very specific so I wasn't sure if I would need to melt the sand to form the lenses but I knew I could use a glue/sand mixture for the body (shaped by a mold while it hardened).
Naturally I got the answer "wrong" and nobody would listen to me. That episode basically represents how my entire life has gone when dealing with other people...
Parent
Re:Wow smart scientists... (Score:4, Funny)
Otherwise known as "Too smart for your own good." That happened to me all the time while I was growing up.
Now people just think I'm a crank when I make non-linear associations like that.
Parent
Not just schools, but everywhere (Score:3, Insightful)
It's not just the school systems that frown upon non-standard answers, it's the majority of society. In many situations, propose an idea even slightly outside of the predominant group-think, and watch how many folks start to get offended/shoot it down without thought.
For example - I had a bos
Re:Wow smart scientists... (Score:5, Insightful)
Background = 00110000
UncloakedObj = 11100000
CloakedObj = 00001100
CloakShows = 11110000
Parent
Re:Wow smart scientists... (Score:5, Informative)
Only on /. would someone try to explain such science in terms of bitmasks. :)
Parent
Re:Wow smart scientists... (Score:4, Funny)
Parent
Re: (Score:2, Insightful)
Firing while cloaked (Score:5, Funny)
The better question is, can they fire while cloaked? I hear the Klingons made substantial advances in that area.
Not a dupe, but... (Score:5, Funny)
"Gee, if we had enough money, we could make your troops invisible, Mr. General Sir."
wait (Score:5, Funny)
Jeez (Score:5, Funny)
Everyone knows that a tachyon sub-space burst from the main deflector dish invariates the sublimated inverse proportional fields that all cloaking devices use.
Phase the array with multi-numinal values and any cloak in the perimeter will be dropped due to subversive nominal decay but only if you attune your tertiary sensing systems to compensate for the quadralinear flux.
This is all so simple, and I have to wonder about the credentials of /. editors that would post such elementary issues on this website.
I mean really, this is first trimester stuff that any recruit can do off the tops of their heads.
Re: (Score:2)
... and, Mr. Data.
Yes, sir? ... Nicely done!!!
Go back to Academy, Ensign. (Score:2)
That's the oldest trick in the book, and it only works against objects that are polaron neutral against the subspace background. And since most variations of phase-harmonic shields break polaron symmetry any military warp-capable ship is immune.
How to not be seen at a distance, low-tech style.. (Score:5, Funny)
Re:How to not be seen at a distance, low-tech styl (Score:5, Funny)
Notquitecajun, will you stand up please. (gunshot)
This demonstrates the value of not being seen.
Parent
Re:How to not be seen at a distance, low-tech styl (Score:4, Interesting)
Parent
Re:How to not be seen at a distance, low-tech styl (Score:5, Informative)
I'd like to see your source on that one, Assuming that sound can't move through the rest of the rifle(for sake of discussion) and will only escape out of the muzzle the shooters ear is about 1 meter away form the source. The Barrett M82 (using .50 BMG round) has a max effective range of 6800m with a muzzle velocity of 853 m/s. That means that it will take that round 7.79 seconds to go the max distance or 2.16 seconds to go the effective range of 1850 meters.
The speed of sound is 340.29m/s, so for the sound of the gun shot to go from the muzzle to the shooters ear 1 meter away will take apx 0.0029 seconds.
At 853 m/s the round will have only traveled 2.47 meters away from the muzzle.
Provided the target is less than 2.47 meters away then yes the will have a whole in them before you the shooter hears teh shot, but you said thousands of yards, which as we proved is just wrong. Now had you said that you the target will have a whole in you before you the target even hears the report then yes you would be right.
Oh and you totally misused the joke anyway of th GP. It was a Monty Python sketch. /All figures from GIS and wikipedia) //Math could be wrong, please correct me if I'm wrong
Parent
Only transulcent objects? (Score:2)
This must only work with translucent objects. The other method works with any object.
It's trap (Score:2)
Soon, you'll get these kindof presentations:
"This! is the best thing ever since the previous thing that was the best thing ever!" "Can I see?"
"It's right here, it's cloaked.. You can see it but you cannot perceive it. But believe me, it's there."
"If it's invisible, it must be good! *throws monnies*"
If you give it some thought (Score:5, Insightful)
This technology, if adopted by the military, will probably only be useful against civilians. Against another sophisticated military there will always be a way to detect what you're trying to hide through other means than visible light - magnetism/alterations in the earth's magnetic field (in the case of big chunks of metal, heat), RF emissions, overhead imaging, radar, sonar, etc.
You won't be able to hide your tank like this, but the small laser turrets to keep the neighbor's cat off the lawn might work... now if only those sharks would stop swimming.
Re: (Score:3, Interesting)
Re:If you give it some thought (Score:5, Insightful)
I'm not so sure about that. I mean, the military currently uses a whole bunch of stealth technology against their enemies: everything from simple paint color and camouflage, to radar-reflective stealth paint or ultra-quiet engines for submarines. None of these are perfect, but all are useful.
You may not be able to make yourself 100% invisible to an enemy that has good tech, but as long as you can give yourself an advantage in hiding, it's worth using. The "advantage" could be increased survival (enemy hit accuracy is reduced), better range (you can get closer before being detected), or maybe just the cost to the enemy for them to launch all the overhead imaging and use all magnetic field sensing equipment you just mentioned.
If cloaking became viable, it would definitely be used by the military against other high-tech enemies. In battle, every advantage counts.
Parent
Re:If you give it some thought (Score:4, Insightful)
This technology, if adopted by the military, will probably only be useful against civilians.
Or unsophisticated military. Against other sophisticated military, it's good to have the tech first because that allows research into counter-tech sooner. One way to beat the enemy is to force them to spend too much in resources keeping a stalemate.
Parent
The key point (Score:4, Interesting)
... in your argument is "against another sophisticated military".
However this is rarely the case. Nowadays most engagements the US Military is involved in are against people with little more than 25-50 year old weapons. The problem the US Military has is the on the ground war against these kinds of insurgents - this tech. would be invaluable against them, you could approach a camp on foot without fear of being seen.
Parent
Re:If you give it some thought (Score:4, Insightful)
You obviously haven't given it much thought. If your logic held true, there would also have been no reason to develop stealth technology for our aircraft. As someone else astutely pointed out in response to you, every advantage helps. There would be many, many applications for 'cloaking' technology against even high tech militaries.
Of course, it's fashionable around here to say will really only be useful when used against civilians.
Parent
I just need an old-kind Invisibility Cloak (Score:2)
All invisibility cloaks to date work by hiding an object embedded inside them.
This conventional kind is enough for me. Where can I get one?
Re: (Score:2, Funny)
You do realize you will be blind, right?
Unless you poke some holes in your cloak, and then people will just see eyes floating in the air.
Actually, that seems like a fantastic idea.
Sign me up!
Re:I just need an old-kind Invisibility Cloak (Score:4, Funny)
You do realize you will be blind, right?
Unless you poke some holes in your cloak, and then people will just see eyes floating in the air.
Actually, that seems like a fantastic idea. Sign me up!
Okay so that's one invisibility cloak for...Mr Anonymous Coward.
Parent
The fast show (Score:2, Funny)
So, in summary... (Score:2, Funny)
General: "That's amazing, let's try these out."
Scientists: "Right, Here is one you can try, but if you want more then we need money... a lot of money."
General: "Sorry, the deals off, the soldiers say they can't see out of it when they're inside it."
Scientists: "Give us a few minutes."
[Obligatory view of shed with hammering and sawing noises]
Scientists: "Okay, how about your troops just hide behind it?"
Big-ass photo... (Score:2, Troll)
Re:Big-ass photo... (Score:5, Funny)
Parent
Re: (Score:3, Interesting)
Well, no, actually they take a photo of the subject, make a sort of translucent negative, and put it in front of the object and make the object disappear from view. Slightly more ingenious because the background can change.
Not sure how they handle the "light behind the 'cloaked object' isn't shining through it" scenario. Presumably you could bend the light around the object and back into it's orignal path - but that's the 'embedded cloaking device' as far as I can tell.
wrong road (Score:4, Funny)
Re:Yawn (Score:5, Funny)
Parent
Re:Yawn (Score:4, Funny)
You'll know when cloaking is really working when the monthly dupe of "cloaking, this time for real" stops showing up here.
Because they managed to cloak the article?
Parent
Re:Yawn (Score:4, Funny)
Parent
Re: (Score:2)
All invisibility cloaks to date work by hiding an object embedded inside them.
I had no idea we had working cloaks! Cool. Having an invisibility cloak would make raiding the Sorority Girls' dorm so much easier for the Engineering house. Where can I get one? :-)
Re: (Score:2, Insightful)
Re: (Score:3, Funny)
Re: (Score:3, Funny)
50% of the population does it all the time (Score:5, Funny)
How hard can it be if even girls manage it?
Parent
Re: (Score:2)
Get implants and shave.
Re: (Score:2, Insightful)
Re: (Score:3, Funny)
They should be working on the SEP field.
Hitchikers guide reference:
"The technology required to actually make something invisible is so complex and unreliable that it isn't worth the bother. The Somebody Else's Problem field is much simpler and more effective, and can be run for over a hundred years on a single torch battery. This is because it relies on people's natural predisposition not to see anything they don't want to, weren't expecting, or can't explain."
You don't even need a battery. Just build it to look like a sink full of dirty dishes in a student household and no one will see it.
Re: (Score:2)
Re: (Score:3, Interesting)
no, because then you're behind/inside the cloak and your visibility in the cloaked direction is zero. you're not unbending the light with a complementary image. if the light source is behind you, you'd just look like a jackass holding up a bed sheet.
the method proposed in the article is to hide objects outside (hence, "How to Cloak Objects At a Distance") of a cloak using a complementary material. no materials have yet been developed to do this.
it doesn't even necessarily have to be a physical material. if