Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Scientists Make Item Invisible to Microwaves 219

Vicissidude writes "A team of American and British researchers has made a cloak of invisibility. In their experiment the scientists used microwaves to try and detect a copper cylinder. Like light and radar waves, microwaves bounce off objects making them visible and creating a shadow, though it has to be detected with instruments. If you can hide something from microwaves, you can hide it from radar and visible light. In effect the device, made of metamaterials — engineered mixtures of metal and circuit board materials, which could include ceramic, Teflon or fiber composite materials — channels the microwaves around the object being hidden. When water flows around a rock, co-author David R. Smith explained, the water recombines after it passes the rock and people looking at the water downstream would never know it had passed a rock. The first working cloak was in only two dimensions and did cast a small shadow, Smith acknowledged. The next step is to go for three dimensions and to eliminate any shadow."
This discussion has been archived. No new comments can be posted.

Scientists Make Item Invisible to Microwaves

Comments Filter:
  • Moo (Score:4, Insightful)

    by Chacham ( 981 ) on Thursday October 19, 2006 @01:54PM (#16504489) Homepage Journal
    A team of American and British researchers has made a Cloak of Invisibility. Well, OK, it's not perfect. Yet. But it's a start, and it did a pretty good job of hiding a copper cylinder.
    So, we'll just just change his name to Harry Copper.

    This title is absurd. Invisibilty?

    The research is very kewl though, and i hope it progresses. But why not lay off the stupid titles, and produce results based on kewlness or usefulness, instead of what can be termed with a popular buzzword. Information Technology is bad enough from its buzzword infusion. Must we destroy legitamte research/discoveries as well?
  • Color me dubious (Score:2, Insightful)

    by Ancient_Hacker ( 751168 ) on Thursday October 19, 2006 @01:59PM (#16504567)
    Sounds mighty fishy.

    You might be able to channel some energy around an object, but:

    • There's no way to effectively pass an image through. You can't detect that the light is hitting at a 43 degree angle, therefore you have to pass that photon through and emit it from the other side at the same angle.
    • Detecting, moving, and reemitting the light loses a certain and irreducible percentage of the light, so the "invisible" image is always going to appear darker.
    • Doing this from every possible angle of source and destination is almost infinitely complicated.
  • Re:bad analogy (Score:2, Insightful)

    by wyldeling ( 471661 ) on Thursday October 19, 2006 @01:59PM (#16504573) Homepage
    Both follow the path of least resistance. It just happens that most of the time light follows a straight line. A mirage [] is an example of when light doesn't follow a straight line.
  • by Anonymous Coward on Thursday October 19, 2006 @01:59PM (#16504579)
    "The next step is to go for three dimensions and to eliminate any shadow..."

    Uh, yeah. This is a bit like saying "now that we've learned to jump 2 feet in the air, the next step is to jump up to the moon." That's a hell of a difference i nmagnitude and it's going to take enormous improvements in scientific understanding to achieve, if invisibility cloaks are ever possible at all.
  • Re:Just talking... (Score:3, Insightful)

    by Daniel_Staal ( 609844 ) <> on Thursday October 19, 2006 @02:01PM (#16504609)
    I'd say the simplest is just to make a few small holes in the cloak. If they are small enough they will be overlooked. Attach a small camera to the hole, and you've got a good chance of a wide field of view with a dust-mote sized hole.
  • Stealth Ship (Score:5, Insightful)

    by rlp ( 11898 ) on Thursday October 19, 2006 @02:13PM (#16504815)
    Sounds like a better version of stealth. I recall reading that an early attempt at a stealth ship did TOO good of a job of dispersing microwaves (compared to background reflection of empty ocean) and showed up as a moving 'hole' on surface radar screens. Assuming that this technology could be applied to bending light around an object, it would need to do so without creating obvious distortions.
  • by angelasmark ( 856143 ) on Thursday October 19, 2006 @02:16PM (#16504869) Journal
    You obviously didn't grow up on too much star trek. Any true trekkie would know that its a Romulan Warbird and a Klingon Bird of Prey...
  • by toddbu ( 748790 ) on Thursday October 19, 2006 @02:20PM (#16504937)
    The reasoning for making them illegal was that the criminal element used them to evade law enforcement.

    This assumes, of course, that the criminal element (or anyone else for that matter) will be able to use the cloaks successfully. Think about how hard it would be to rob a bank. If you're wearing the cloak then how does the teller know that you're there demanding money? Perhaps you just want to cloak the getaway car. How do you find it back when you're done with the job? Even if you remembered where you parked it, finding the door handle would be problematic. If you could turn the cloak on and off then maybe you'd be ok, but with this particular technology it doesn't look like that's possible.

  • by UbuntuDupe ( 970646 ) on Thursday October 19, 2006 @02:20PM (#16504941) Journal
    True, but to dismiss something like this because it's still possible to detect the cloaked object would be in error. Think about the camoflauge gear militaries already use. You can still see them. HOWEVER, if you're not looking carefully enough, it's a lot easier to miss them in certain environments. The point of cloaking or camoflauge is not to make you undetectable, but to make it require more resources to detect you, just like the point of encryption is not to make the data unreadable to others but to make the threshold required to read it (in terms of money, time, etc.) high enough.

    An infiltrator who appears as a dark spot will still be much more effective in how he's so hard to detect.
  • by MrHops ( 712514 ) on Thursday October 19, 2006 @02:23PM (#16504981)
    Seems to me, even given perfect invisibility, that the object in question would radiate energy all by itself.

    Do some spectranalysis, and you immediately know something fishy is going on. (Copper won't radiate like the ground, for example)
  • Re:bad analogy (Score:4, Insightful)

    by zippthorne ( 748122 ) on Thursday October 19, 2006 @02:30PM (#16505145) Journal
    fluids follow the path of least resistance. Light follows the path of least time.
  • by Rei ( 128717 ) on Thursday October 19, 2006 @02:39PM (#16505359) Homepage
    That's silly. The teller can hear you.

    Even if there was no "on-off" button on this, it would be trivially easy to "make" one. Paint water colors on all or part of the object that you can wash off. Tape on visible objects. Put a cover over it. Etc. This assumes that the cloak *itself* isn't flexible, allowing you to take that on or off.

    Also, I doubt it'll be perfect invisibility. Even if, to the naked eye it appears perfect, I doubt it would to custom goggles analyzing the scene. Surely there are some wavelengths that it won't work on (from the sound of it, you need to customize a layer of this for a *specific* wavelength). Or the polarity could be thrown off. Or all sorts of other things.
  • by XenoRyet ( 824514 ) on Thursday October 19, 2006 @02:41PM (#16505413)
    The real issue, and the major downside to a cloak of this nature, is how do you see where you're going while you are wearing it?

    If it's diverting all the light around you, there's no light to get in and hit your eye so you can see.

    The solution would be much more complex than the basic cloak. You'd have to let some light in, but make sure it didn't get back out again. I can see that being problimatic.

  • by CmdrGravy ( 645153 ) on Thursday October 19, 2006 @02:43PM (#16505459) Homepage
    I'm sure any relatively non moronic criminal would quickly work out how to maximise the benefits of being totally invisible and avoid the risks you have mentioned. For example if you were invisible you wouldn't need to ask the teller anything, just follow someone into the secure area of the bank, hang around for a while seeing where all the keys etc are kept and then wander into the vault stuff as much cash as you can carry under your invisibility cloak and wander out again. I don't see why you'd need a getaway car but assuming that you did then cloaking it when you parked it would be a stupid idea, you'd only activate cloaking if you were actually being pursued and trying to hide. With a cloak of invisibility and half a brain you should never be in any situation where you're being pursued.
  • by DrKyle ( 818035 ) on Thursday October 19, 2006 @02:47PM (#16505527)
    There's this thing called a pinhole camera, it's a relatively new advance. By allowing this pinhole of light in with the proper equipment just enough light could be absorbed to allow the user to navigate. Of course there would be a visible pinhole floating in space, but could you reliably pick it out at a distance of more than a few feet?
  • by c6gunner ( 950153 ) on Thursday October 19, 2006 @03:11PM (#16506007)
    It just means that organized combat would evolve to take advantage of them also. Ever since WW2 we've been moving to smaller and smaller units working as independent organizations, then re-combining to carry out more complex tasks. With the introduction of cloaking technology you'd see the extreme end of that. 4-8 man squads operating independently on foot and light vehicles, hunting down guerrillas the same way the currently hunt us. Biggest obstacle to us doing that NOW is that we're so easy to identify. If we could have small units operating all over a city, totally invisible to anyone...well, good luck trying to plant IED's, or even gathering at your buddy Ahmed's house to discuss tomorrow's plan of attack.
  • by gutnor ( 872759 ) on Thursday October 19, 2006 @03:20PM (#16506195)
    You only need 2 little holes of 5 mm and you have all the lights needed for your eyes. Considering the likely imperfection of the invisibility suit, it is likely that when you can spot the holes, you are already close enough to detect the wearer.

  • by avirrey ( 972127 ) on Thursday October 19, 2006 @03:26PM (#16506301)
    I'm not as smart as thermopile, but I will say that the definition of 'invisible' for the most part should be limited to the human visual range. While this may be the ultimate goal the truth is that our 'detection' of a massive range of frequencies across the spectrum is so advanced, that anyone hiding behind a 'vision inhibiting' cloak could still be detected by other methods. Again, I'm not a hard-core physicist, but I would assume if you do some sort of city-sweep with X-rays you should be able to pick up spectral anomolies since these cloaks presently work in the micro-wave range. Somebody please explain this better if you understand what I'm saying... LoL.
    X's and O's for all of my foes... ^^
  • by JasonTik ( 872158 ) on Thursday October 19, 2006 @03:52PM (#16506841)
    You'd have to let some light in, but make sure it didn't get back out again.

    This would be devastating to the cloaking effect if the same wavelengths were let in that you were trying to cloak against. Your cloak would make the area it covers darker by not passing all light.

    If you were trying to cloak against visible, you would have to use microwave or something else to look at things with to avoid this.
  • by Anonymous Coward on Thursday October 19, 2006 @05:01PM (#16508225)
    Your points are well taken. However, this is not a single experiment, but a way of proving that there is an operational way to work with waves that was previously only theoretical. When the audio-cassette was first invented it was assumed to be so crude that it could only be used in dictation machines. The last manufactured high-end cassette player, the 'Nakamichi Dragon' I believe, combined with Dolby-S noise reduction actually recorded a music signal that was higher in frequency and more fully defined in terms of harmonic coherence than could be obtained from a standard audio CD (albeit with higher, though inaudible, wow and flutter). In like manner, when the first laser was invented there was some talk about it being useful for scientific measurements. Remember that the founders of Intel originally believed that the only use for a computer in the home might be to store recipes. Even in 1995 an issue of Popular Computing reported that the Intel 486 was so powerful (at 66mhz) that only servers really needed that level of CPU. Invisibility to light was made popular by the Klingon Cloaking Device, but this technology is probably going to be more useful in cloaking us from many other forms of electromagnetic energy. Consider the fact that their experiment worked on the first try. Even the Wright brothers never had that kind of track record. Methinks that this growing understanding of diffraction technology may be the tip of a 21st Century iceberg.
  • Not only that (Score:3, Insightful)

    by phorm ( 591458 ) on Friday October 20, 2006 @01:49AM (#16513091) Journal
    But a moving object is still traceable, as it will physically disturb the environment around it. A human will trample vegetation, break branches, or leave footprints etc. A tank will leave track prints, stir up a whole lot of dust, and many other such things.

    So this technology would be most useful for hiding static vehicles/persons, or perhaps even moreso for hiding buildings (think, a whole, semi-invisible bunker).

    I wonder how it would affect sound waves as well. Perhaps sonar would pick up things that radar would not. After all, a mirror or glass might be used to distort or reflect light, but does little against sound...

"My sense of purpose is gone! I have no idea who I AM!" "Oh, my God... You've.. You've turned him into a DEMOCRAT!" -- Doonesbury