Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Sci-Fi Science

Duke University Creates Perfect, Centimeter-scale Invisibility Cloak 96

MrSeb writes "Scientists at Duke University have created the first invisibility cloak that perfectly hides centimeter-scale objects. While invisibility cloaks have been created before, they have all reflected some of the incident light, ruining the illusion. In this case, the incident light is perfectly channeled around the object, creating perfect invisibility. There are some caveats, of course. For now, the Duke invisibility cloak only works with microwave radiation — and perhaps more importantly, the cloak is unidirectional (it only provides invisibility from one very specific direction). The big news here, though, is that it is even possible to create an invisibility cloak of any description. It is now just a matter of time before visible-light, omnidirectional invisibility cloaks are created."
This discussion has been archived. No new comments can be posted.

Duke University Creates Perfect, Centimeter-scale Invisibility Cloak

Comments Filter:
  • by Anonymous Coward

    I always hoped they would work on Warp technology first....

    Also, does this mean we are the Romulans....

    • ... well, I keep hearing about 'disruptive' technologies.

    • Re:Cloaking first? (Score:4, Interesting)

      by captainpanic ( 1173915 ) on Monday November 12, 2012 @10:55AM (#41956175)

      Looking at the capabilities of mobile phones today, I would suggest the tricorders arrived before the cloaking.

      What I am saying is that it's one thing to develop an invisibility cloak. It's another thing altogether to avoid being tagged while wearing it.

    • There is a Fictional Element to Science Fiction.
      We have observed Light being bent we know it is possible.
      We have not observed anything going faster than light. We don't even know if we have the means or power to warp space/time, it is purely theory.

      • by Gilmoure ( 18428 )

        Strictly speaking, I'm warping space as I sit here. A probably time as well, seeing as how I'm wasting it on slasgdot. But yeah, warping space/time to have travel that appears to exceed spacetime? Only hallmark channel movies and algebra classes taught by high school football coaches can approach that level of time fluxuation.

        • If you're using phrases like 'time fluxuation' you're well on the way to making one of those websites [timecube.com] with ground breaking post Einstein theories that are mysteriously ignored by The Cabal of conventional physicists.

    • I always hoped they would work on Warp technology first....

      Technically, the warp [wikipedia.org] always comes first when you are working on a cloak. The warp is the layer of threads that you weave the weft [wikipedia.org] through to create the fabric. If you don't have the warp first, the fabric, space and time are simply chaos.

      • by EdZ ( 755139 )

        If you don't have the warp first, the fabric, space and time are simply chaos.

        Unless, of course, the Universe is crocheted.

    • by osu-neko ( 2604 )
      We tend to be Romulans during war, and Ferengi the rest of the time...
    • Now that is funny! oh and of course we are! lol

  • Hmmm (Score:5, Funny)

    by ciderbrew ( 1860166 ) on Monday November 12, 2012 @10:38AM (#41956081)
    I'll believe it when I see it.
    • Re: (Score:2, Funny)

      by BriggsBU ( 1138021 )
      I'll believe it when I /don't/ see it.
    • Unidirectional microwave-only cloak -> omnidirectional visible light cloak?

      It's gonna take a little more than "a few years".
      • Re:Hmmm (Score:5, Interesting)

        by vlm ( 69642 ) on Monday November 12, 2012 @11:06AM (#41956265)

        Unidirectional microwave-only cloak -> omnidirectional visible light cloak?
        It's gonna take a little more than "a few years".

        The biggest problem I see from having done lots of RF engineering in the lower microwave range (mostly FCC part 97, but some telco work, aside from the wifi stuff that "everyone" does) is specs always improve, but the basic layouts / schematics / ideas don't change very much.

        Higher freqs? Sure. A heck of a lot of orders of magnitude? Um, maybe, over the course of a lifetime and billions of bucks. Unidirectional to omni? Um no.

        You can make a "better" horn antenna. You can do crazy stuff to eat the sidelobes. You can make it lighter, or wider bandwidth, or better behavior when it multimodes. You can make it lower loss. But fundamentally, its still a microwave horn antenna. This fundamental issue is analogy to trying to make a unidirectional cloak.

        This doesn't mean its useless. You know what would be funny? A anti-anything missile that is radar invisible from the pointy end. Who cares if you can see it from the back or side, its too late by then. To the best of my limited knowledge from playing Harpoon, etc, all American anti-anti-ship missiles are radar guided as are the ancient Phalanx miniguns.

        One interesting RF observation is its a serious challenge to "really" do microwave RF work over a factor of 2 in freq. Can be done, but doesn't mean its easy or its more than cheating (multiple colocated systems... making a big pile simply isn't technologically interesting). The relevance is an X-band invisible car would probably not be invisible at K band. Or something invisible to red is probably going to be blue visible, unless you run multiple systems. Or something invisible to blue is probably not going to be invisible to IR targeting lasers.

        • by Anonymous Coward

          Higher freqs? Sure. A heck of a lot of orders of magnitude? Um, maybe, over the course of a lifetime and billions of bucks.

          Optical frequency metamaterals have already been demonstrated. They can be made via various lithography techniques, so in some sense it is not that hard to make things smaller, to the limit of what current lithography research is. There is still a lot of work to be done in improving the quality, and figuring out how to best apply multitude of lithography techniques and materials to get the desired structures (or designing structures that work better with those methods), so it is probably decades away. I

        • Higher freqs?

          The problem isn't just higher frequencies, which as you say getting to optical frequencies will be really hard, but not impossible. The rest of the problem is bandwidth. I can't find the source article for this, but I'd bet the bandwidth is tiny. Visible light covers and entire octave of bandwidth. I've seen zero sign that metamaterials will ever have close to that much bandwidth. Increasing the frequency just means making things smaller. Most of the metamaterials have elements that resonate at specif

    • by Gilmoure ( 18428 )

      Too small for my figures (25 mm).


  • Optimism. (Score:5, Insightful)

    by Anonymous Coward on Monday November 12, 2012 @10:39AM (#41956087)

    "It is now just a matter of time before visible-light, omnidirectional invisibility cloaks are created."

    Wow. Just Wow. Just because we sent men to the moon, it does not mean that we'll be traveling to other galaxies soon.

    Unless of course by "just a matter of time", they mean like a hundred thousand years.

    • by slim ( 1652 )

      It depends on will.

      It was just 61 years from the Wright Brothers demonstrating heavier-than-air flight, to the Apollo 11 moon landing.

      So space exploration has slowed down a bit in the last 40 years. Who knows what'll happen in the next 60?

      • Re:Optimism. (Score:4, Insightful)

        by CastrTroy ( 595695 ) on Monday November 12, 2012 @12:01PM (#41956899) Homepage
        I always like to refence this Hitchhiker's Guide quote

        Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

        There's a big different between going to the moon and even something like going to Mars. It only took Apollo 11 astronauts 3 days to get to the moon. Even the shortest trips to Mars have taken close to 300 days. And Voyageur 1 has been travelling for 25 years and is only now reaching the edge of the solar system.

        While warp speed and worm holes could allow matter to travel vast distances over short periods of time, I don't know if actual things could travel though a worm hole or at warp seed without being torn apart.

        • Re:Optimism. (Score:4, Interesting)

          by slim ( 1652 ) <john@NosPam.hartnup.net> on Monday November 12, 2012 @12:15PM (#41957049) Homepage

          Buzz Aldrin's proposed Mars Cycler would take about 5 months to shuttle "stuff" to and from Mars' orbit.

          • Yes, but from what I'm reading, you have to wait over a year between trips so the planets line up correctly so that you can make the trip in such a short period of time. Doesn't really help out that much. And better hope you don't miss your launch window, or you might have to wait until the next time the planets align. Also, even at 5 months, that still an extremely long time to be traveling through space.
    • by jamesh ( 87723 )

      That was my thought too. I am able to jump and stay in the air for a short amount of time, therefore it is only a matter of time before I can stay in the air indefinitely.

  • So, the cloak only does a very small area. Hobbitses?

    And the cloak only does it from one direction? ... so ... multiple cloaks?

    And the cloak only does a certain type of radiation? ... better directed EMP bombs?

    I guess it's all pretty neat. My big problem with the article? It's not a CLOAK if it's only 1cm by 1cm. It's more of a patch. Or a stamp.
    • One direction like one exact angle of incidence. Multiple cloaks won't help because you need an infinite number of them, or at least you need them per angle based on the bandwidth of microwave and the radius of the cloak--meaning a lot. Too much. It's a huge leap from "We've gotten elevators to work by using a rope and pully and waterwheel" to "soon we'll be able to lift things into space by anti-gravity".
    • by jamesh ( 87723 )

      And the cloak only does it from one direction? ... so ... multiple cloaks?

      No, the cloak only prevents you being seen by a currently popular boy band.

  • I think someone invented that long ago... Have you ever dropped an smt component on carpet? I have it just disappears.
  • I'm getting my body armour, dread wigs and spiky face masks now before they all sell out!
  • by Tastecicles ( 1153671 ) on Monday November 12, 2012 @10:55AM (#41956173)

    Surely it's gotta have a tailpipe...

  • perfect (Score:3, Funny)

    by HPHatecraft ( 2748003 ) on Monday November 12, 2012 @10:56AM (#41956185)

    now all we need to do is drag Stuart Little out of rehab (child stars... what more needs to be said?), and get him trained up over in Langley. With this invisible cloak, we can take rodint (rodent intelligence) to the next level.

    Can someone look up cat populations in Iran at CIA's World Fact Book?

  • by samazon ( 2601193 ) on Monday November 12, 2012 @11:03AM (#41956237)
    My Harry Potter cosplay will be complete! Win!
  • If someone ever does produce an actual cloak of invisibility, we're going to have a huge problem as the foundations of our law enforcement will go out the window.

    It will in effect legalize murder, since anyone with an invisibility cloak can sneak up on a victim and blow his/her head off. Even better, with printable weapons, the murder weapon won't be traceable either.

    Perhaps the decision we made long ago to rely on external control (e.g. law enforcement) instead of internal moral compass, will come back to

    • by wbr1 ( 2538558 ) on Monday November 12, 2012 @11:11AM (#41956301)
      It has always been an internal moral compass that guides us. Few people do not commit murder or any other crime because of the fear of law enforcement.
      The question becomes, does that moral compass derive from superstitious psuedo-belief in some omniscient power, government instilled fears, or a true sense of what is the path of the least harm to the fewest numbers of others?
      If I really want to kill someone, or rob them, or rape them, I will find a way to do it, law and others be dammed. It simply becomes a matter of proper planning and (ahem) execution.
      The invention of the knife did not 'legalize' murder, neither did the invention of the gun, or the fist for that matter. What legalizes it is our own mind and definition of moral. Regardless of the tools used.
      Law enforcement, like much religion, is simply a fear mongering device used to direct the thoughtless masses.
    • by vlm ( 69642 )

      If someone ever does produce an actual cloak of invisibility, we're going to have a huge problem as

      In the good olde days on /. this would have rapidly devolved into "how are 5000 nerds wearing invisibility cloaks all going to simultaneously fit in the 12 person college cheerleaders girls shower room and what happens when their crappy homemade wiring and/or ARDWEEEEEEEEENO microcontroller shorts out because of the shower water?" but no, we have to have whacky hollywood movie plots about murder.

      Insider trading is a much more fun example. What did the corporate board really talk about? And how much can yo

    • The vast majority of murders today don't have any eye witnesses, and yet many of those cases still get solved and the perpetrator caught. Furthermore, it really isn't hard to sneak out behind someone and shoot someone today, without even being seen by the victim. So an invisibility cloak will only make it slightly easier to kill someone, and won't make it any harder to catch them. Not much of a game changer.

  • Perfect? (Score:4, Insightful)

    by guttentag ( 313541 ) on Monday November 12, 2012 @11:34AM (#41956531) Journal
    From the Oxford English Dictionary:

    adj. /'perfikt/
    Having all the parts and qualities that are needed or wanted, an no flaws or weaknesses.

    If there are caveats, it's not perfect. Don't slap false labels on things to make them sound more impressive. Call it what it is.

    • by Anonymous Coward

      Webster: Definition of PERFECT
      a : being entirely without fault or defect : flawless
      b : satisfying all requirements : accurate
      c : corresponding to an ideal standard or abstract concept

      In this case, definition c applies.

    • by radtea ( 464814 )

      If there are caveats, it's not perfect

      Yeah, the number of times "perfect" was used in the first part of the summary was a clear flag that "except" was going to loom large in the second part.

      "Perfect" is such an abstract concept that almost all of its uses are misleading: the primary purpose of abstraction is to lie and mislead, and the more abstract the concept the few non-misleading uses it has. As such, "perfect" is a word that should be used very rarely in an engineering context.

  • by some1001 ( 2489796 ) on Monday November 12, 2012 @11:37AM (#41956567)
    The idea that we're "soon" to have invisibility cloaks that are both omni-directional *and* handle visible light is an unfounded one. True, maybe the underlying foundations are set well and the science is understood. But here's the issue: metamaterials ("invisibility cloaks" as a rule, fall into this category since they're properties are determined by the structure of the materials - not the material itself) have specific patterns in the structure. Microwave radiation has a wavelength between 1 mm and 1 m. Visible light has a wavelength of 390 to 750 nm. We are talking about four orders of magnitude.

    The structure of the metamaterial needed to handle visible light is going to be out of our reach for quite some time until we can design a better way of handling structural details on the nanoscale and beyond (right now, the best methods are self assembled, and those methods usually aren't good for the massive complexity you'd desire).
    • The claim of 'Centimeter-scale Invisibility Cloak' should have been 'x wavelengths wide invisibility cloak' . Since anything that's say a tenth of a wavelength is always invisible, I can make an object of 10m wide that's completely invisible, provided the source is a 10MHz radio emitter.

      • Small things still scatter light even if they are too small to resolve. It's why the sky is blue.

        • Ok, and if you place many small things together you get a large thing so one small thing would have to do 'something' at least. I overstated that. But the point remains: the impact on the incoming wave depends on relative size of the object to the wavelength.

  • The end result is an invisibility cloak that can perfectly hide a 3×0.4-inch (7.5x1cm) cylinder from microwave radiation.

    Isn't this basically where they've been with this research for ages? The only new thing I can see here is that the material was cut into a diamond shape to minimize reflections.

    • Yes, the reflections being the thing that prevented previous version from being considered "perfect" cloaking devices. But don't let my logic stop you from denouncing this as a let-down...
  • Well, that's easy. (Score:4, Insightful)

    by Minwee ( 522556 ) <dcr@neverwhen.org> on Monday November 12, 2012 @11:42AM (#41956627) Homepage

    I already perfected a centimeter scale invisibility cloak which works in visible light, but is unidirectional.

    It involves using a digital camera, a printer, one square centimeter of paper and a bit of tape. Naturally, there are some limitations to where it can be used, but those are just details for the engineers to deal with.

  • Magicians have been doing that for a long time.OK, the mirrors divert light under the table or whatever, so it's not a free-standing object, but is it in this case?
  • Man size invisibility cloaks or Guymelef size invisibility cloaks?

  • If you click on the photo to get a bigger view, it's a direct link to a bigger JPEG. Not lightbox, no website template, no nothing.

  • So the trick is not to move your head. Squint a bit. And only use microwave-vision. Those are a lot of constraints.

    I have a solution that's quite a bit simpler: Look entirely the other way. Total invisibility!

    Nevertheless their achievement is actually very cool.
  • Wow, this is sensationalist titling on par with Digg or Reddit. Title: New Earth 2.0 found 2 miles outside Earth's atmosphere! Body: No not really. What we meant to say is that a planet approximately the size of the earth with no possibility of hosting human life was found far beyond the Sloan Great Wall. Same thing, different story.
  • ...I didn't see it coming.
  • Now, I'll admit that I totally want one, but are there any non-evil (or non-military, if you prefer) uses for a working invisibility cloak? All I can think of is "spying on people" and "making it easier for soldiers to kill people." Are there civilian applications?
  • Now I can walk around with my zipper open and no one'll notice.
  • I remember the same thing said about nuclear rocket ships, now that we have conquered the atom....in 1950...

  • "the cloak is unidirectional (it only provides invisibility from one very specific direction)."

    This is reminiscent of the 1930s Hollywood special effect called the "glass shot," which looks perfect from the point of view of the camera, but not from anywhere else.

    "It is now just a matter of time before visible-light, omnidirectional invisibility cloaks are created." That's about like saying that if David Copperfield can make the Statue of Liberty vanish... as a magic trick... seen under special conditions fr

  • It's for sonar. It's easy to imagine the implications of this sort of technology for submarines.

    I read in the Cold War the US introduced spread spectrum sonar. Spread spectrum means you can operate below the noise floor - only receivers that know the code can even tell that a signal is there. So the day the US switched to spread spectrum the Russians suddenly stopped hearing any US sonar until they cracked the code.

    These invisibility cloaks make no sense at all for visible light because the wavelengths are

  • Another example of a great theory, but nothing practical. So you can hide from microwaves on a single plane of existence, meh. This is almost as bad as putting on a tinfoil hat.

    I think that Top Gear's attempt at invisibility is more practical:

    http://www.youtube.com/watch?v=_TVMpS7Z-5U [youtube.com]

Perfection is acheived only on the point of collapse. - C. N. Parkinson