back to article Chinese boffins crack invisible-shed window problem

Everyone, one hopes, is well aware by now of metamaterial - remarkable conceptual stuff which might be used in coming years to make invisibility cloaks; or more realistically, invisible sheds. Few, however, have spotted the critical flaw in a metamaterial cloak, shed or cladding - people so concealed would no more be able to see …


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  1. Dan

    vanishment boffinry

    "anisotropic negative refractive index material that is impedance matched to the positive refractive index of the invisibility cloak". Riiiight. So, just cancel it out then. Why use 5 words when 18 will do?!

  2. Anonymous Coward

    The real problem here... suppose you leave the Shed-Cloak(c) on and go back to the house, how do you find the damn thing when you come back out? A whole country of angry middle-aged, shed-lurkers running around their gardens and allotments desperately trying to bound off anything that feels like it might be invisible shiplap!

  3. Stuart johnson

    Why a dark patch?

    Because the most elegant solution would be to duplicate the light, digitally or with lenses, polarisation and mirrors, and allow some of the light in and some to pass round...surely?

    If I've got the wrong end of the stick, well, have a laugh anyway!

  4. dervheid
    Paris Hilton

    Ah, the joys of theoretical physics.

    Personally, I prefer the joys of sex, but maybe that's just me.

    And my missus.

    And, well, obviously....

  5. Sam


    Can you put this stuff in glasses so you can find your way into the shed in the first place?

    I like sheds..

  6. Paul Buxton

    If the anti-cloak is apparent from the outside...

    ...why not just have a peephole like the author originally suggested?

  7. Anonymous Coward
    Anonymous Coward

    18 for 5

    Also: Never use a large word when a diminuitive one would suffice...

  8. Kev Jones

    Useful Technology

    ok so... I'm sat in my tank/shed, I can't see out of it, and I think to myself... hmm if only I could see out of this...

    I then spend time and money to research an "anti-cloak" which in effect is nothing more than a flippin glorified periscope?! WOW... you can see why the MOD are interested in this technology... expensive, useless, and, oh yeah, assuming troops are fighting somebody with at least 1 brain cell who can use some form of heat detection camera... totally ineffective!

    I bet the MOD will buy thousands!!

  9. Werner McGoole

    The proper solution... to intercept the light and view a fraction of it. Then boost what remains back up to its original level and pump it out the back (through another anti-cloak, presumably). This would be a man-in-the-middle attack on the light passing through.

    Remember this post when you see someone trying to patent the idea!

  10. Anonymous Coward

    My thoughts...

    "anisotropic negative refractive index material that is impedance matched to the positive refractive index of the invisibility cloak"

    That's exactly what I was thinking of using... of it's close equivalent of a small opening that you can adjust in width much like a curtain.

    Or, you could use a small camera somewhere on the outside and a screen on the inside.

    It just leaves the question of what happens to any light (and heat, which is the same thing) which is produced on the inside, or enters through said aperture? It can't escape because that would give the game away. It cant be converted into heat or noise because that would also be detectable. Maybe the inside has a mirror to direct all this excess energy into the sub-ether, thus producing a pan-galactic gargle-blaster?

  11. Mike Crawshaw

    If I had an invisible shed...

    I would need to see out. How else would I know when to hide the beer and porn when I see the missus coming??? Mere invisibility is no impediment to Her Wrath....

  12. Geoff


    Can someone shed some light on this for me?

  13. Chris Boyle

    Alternate translation

    A strategy well-known to sci-fi fans everywhere: "Reverse the polarity!"

  14. Anonymous Coward

    RE: the real problem here

    Leave the door open?

  15. Colin Morris

    Where's a Klingon when you need one?

    ... or even a Romulan.

    They got this 'can't see in, can see out' invisibility cloak nonsense down to a tee...

    What do you mean these alien races don't really exist?.......

  16. Farmer Hackit

    Why waste all this money?..

    Just make tanks and sheds out of the same materials as motorbikes, afterall, the evidence is there that it works. How can a thousand *SMIDSYs be wrong?

    *(Sorry Mate I Didn't See You)

    Mine's the... ermm... now where did I put it?

  17. Havin_it

    The other problem...

    "...the anti-cloak window would be apparent from outside, but principally as a dark patch on the opposite wall of the shed."

    So let's get this straight: You can preserve the invisibility of your shed to an observer, as long as the 'window' you look out of is facing the observer. So how d'you know which side of the shed the observer is watching?*

    *Apart from the obvious *KLONK!* "AAOW! $*&@! Huh?" when the observer walks into the invisible wall, that is ;-)

    So you press up your Anti-Cloak window to the front wall and can see an enemy soldier cursing and rubbing his head. But you can't see his special forces mate who's crept up silently to the rear, and now has a nice window-sized view of the back of your head. Er, or is it the front? Either way, HEADSHOT!

    Think I'd stick with the peep-hole, as successfully deployed by irrepressible frat-boys and sinister landlords for many years.

  18. Anonymous Coward


    girls showers are predominantly white tiled (er, so I've been told) so having a dark square suddenly appear with a pair of eyes in the middle might cause some concern.

    Obviously in a battlefield no one would notice, but we must consider the domestic uses !!!

    Another thing, purely out of scientific curiouslity, does showerwater, er rain, fall down the outside showing an outline of the cloak?

    Mines the invisible one, when I can find it.

  19. Daniel
    Thumb Up

    nice idea

    but i can see downsides? dirt will make it visible surely? birds flying headfirst into nothing and dying woulc be a give away. and in terms of tanks.... now imagine you go to shoot the enemy... you could have a serious issue with friendly fire (sorry mate didnt see you there!)

    i jus love the idea of placing something behind an invisible shed and telling someone to run and get it..... that would never get old

  20. Martyn Waddington

    Am I reading this right?

    The anti-cloak works by touching the cloaking device. I have one of those already - I call it a hand..

  21. Solomon Grundy


    So the Chinese have created a window? What will they think of next!

  22. jai


    in order to avoid the dark patch at the rear so that it's the perfect solution for lurkers, stalkers and perverts, is it not possible to split the light coming into the front? can't you do something with prisms or mirrors to split the light into two streams? one passing straight through and the other being passed around to the rear?

  23. Mark


    If you made glasses out of anti-cloak, would you see only sheds?

  24. Dale Harrison

    What about Arthur ?

    [Apologies to the non-Python people]

    So Arthur "Two Sheds" Jackson is well f*cked now.

    "Where the hell are my sheds?!"

  25. Peter Richard

    Hide the collection

    A great idea to hide my porn collection in the shed, now where did I put the cloaked porn?

  26. brym

    solution maybe?

    why don't they paint their tanks etc with the meta-maties and stick x-ray panels inside (as seen on the inside of the btr in babylon a.d.)?

  27. Anonymous Coward
    Anonymous Coward

    You Would Not See Eyes

    Now some people appear to have grasped the concept, but for those of you who haven't, the article says you would only see "a dark patch on the opposite wall of the shed".

    This does not provide a window into the invisible shed. What happens is that you steal the light that would have otherwise gone to the back of the shed. The metamaterial has nothing to show, so becomes black.

    It's like switching off a little square in your monitor -- this doesn't become see-through, it doesn't suddenly open a window to the guts of your PC, there just ceases to be an image.

  28. Graham Jordan

    Practical use?

    Ok so really, can this honestly be put to good use by the military?

    You may not be able to see a bunch of tanks coming over the hill but unless they come equipped with slippers or skis you'll still be able to hear the bloody things.

    And what about heat signatures? I'm guessing they'd use a hefty amount of energy, thus radiate enough heat to heat a... what ever may need heating?

    Surely the only people out there who could put this to general good use is perverts.

    Now where do I make my order?

  29. Jim
    Thumb Down

    @Dale Harrison

    He only had one shed!

    ...But had recently suggested he might purchase a second one.

    Pah! The yuff of today...

  30. Anon Koward
    Thumb Up

    Hmmmm perhaps already in use?

    I think my project team have stolen and are using this technology today. Whenever I need them to do an urgent task they bloody well disappear!

  31. Dave
    IT Angle

    @Farmer Hackit

    I see you have trouble with sarcasm? Actual translation of SMIDSY is: "Sorry mate, I didn't see that there was another lane lane there, reserved entirely for motorbikes. Next time I will make sure that I stop two car lengths back from the lights so that there is room for you all to squeeze in."

    Seen on the back of many cars: "I'm a blood donor"

    Rarely seen on the back of motorbikes: "I'm an organ donor - you can have my liver next time it rains."

  32. Anonymous Coward
    IT Angle



    Or, in English "Anry Mim Prick", a particularly virulent sexually-transmitted disease that was introduced to the human race when the DNA in a bacterium causing a mild dose of urethritis in Mr Amry Mim, a Chinese national, spontaneously mutated.

    In the end, despite the best efforts of the Chinese boffins mentioned in the article, Mr Mim did not survive - a vaccine was developed, but paramedics couldn't find Mr Mim as he was in his invisible shed reading porn at the relevent time.

  33. Flocke Kroes Silver badge

    Levitating sheds

    To be invisible, the shed has to take sunlight, bend it to the ground under the shed, let the ground scatter it, and bend the scattered light back around the shed to the eyes of the <strike>showering girls</strike> enemy soldiers.

    There has to be some minimum radius of curvature that the metamaterial can achieve, so the shed would have to levitate to avoid leaving foot-print shadows. How many showers are on the bullet train track?

    While we are at it, metamaterials are only effective over a small range of frequencies. If your shed can hide in grass, it might have difficulty hiding in mud or in the sky. It certainly could not hide from a bat.

    The advantage of the military research budget being wasted on metamaterials is that the budget is not being wasted on testing to see if it is possible to weaponise anthrax with home made kit or if it is possible for badly trained pilots to crash an aeroplane. Oops - too late.

  34. Geoffrey Summerhayes


    So now we have a theoretical solution to a theoretical problem. We still don't have anything close to a shed hiding cloak, scaling up to that level will likely be somewhat troublesome. So I'll believe it when I don't see it.

  35. Anonymous Coward

    To Boldly Go....

    Didn't the Romulans steal this technology from the Klingons (I think copious amounts of Romulan ale was involved).......

    Live long and prosper!

    Mine's the Harry Potter cloak of invisibility .... Oh God! I need to get out more.

  36. Anonymous Coward

    who ever said it would have to be only visible light?

    Me thinks that the researchers are fans of a certain Anime series "Ghost in the Shell" where one of a large number of theoretical systems was a high end stealth material called therm-optic cloaking.

    In todays battlefields visual camouflage has become a fine art but that darn heat signature is an easy giveaway for most modern ordinance and targeting systems. So you don't need to be invisible to everyone but just to those smart missiles they are firing at you.

    If they do perfect a practical heat shield/cloaking system it could be a major factor in any military engagement. For grenade totting self-immolating Neanderthals its of no practical value unless the cost is equivalent to an AK47 and a bag of crisps.

    Mines the one with mu-metal Faraday screen lining (helps protect against those pesky surface penetrating radars)

  37. Anonymous Coward
    Anonymous Coward


    if you can deal with light radiation, why, couldn't you deal with heat radiation?

  38. Ben

    Finding invisible sheds

    It's easy to find your invisible shed, with or without a secret window. Simply paint the shed red. It will now be much easier to find.

    Slip the defence contract in the trenchcoat pocket on my way out, please

  39. Ivan Headache


    I'm not sure about these white tiled battlefields.

  40. Fred

    seeing though invisibility

    the meta materials are very specific in the frequency of light that they make 'invisible'.

    So if you create a large band width meta material, you could create a small frequency gap (IR, or UV come to mind for visible light cloaks) pass through, then frequency shift that light, or use goggles that "see" that frequency.

    This is your "peep hole". No black spot, no floating eye balls.

  41. Anonymous John

    Even if the shed is invisible,

    what about the lawnmower, rusty tools, half empty tins of paint, etc?

    Dead giveaway.

  42. Anonymous Coward
    Paris Hilton

    only good for

    hiding camera's and the like - big machines = too much heat. Surely something our ruling classes must be investing heavily in.

    Paris, because the whole world has seen her dark patch

  43. Ron Eve


    ...the Emperors new clothes...

  44. irspariah

    Invisibility cloak

    The solution is much simpler than you make it out to be. On the job if you fail to kiss ass, your presence, in effect, amounts to total nonexistence. Voila! Problem solved! Any questions?

  45. Homer

    In other words...

    They cut a hole in it.


  46. Anonymous Coward
    Thumb Up

    RE: The other problem...

    Exactly. Just use a Somebody Else's Problem field generator. It runs for centuries on a single double-A battery.

    Thumb, because I still want to get off this planet.

  47. Anonymous Coward
    Jobs Halo

    More Joy of Physics

    More power to your elbow. What a triumph. What a Bootnote.

    And I thought the art of the Bootnote was dead.

  48. Anonymous Coward
    Paris Hilton


    All of this cloaking-peek-aboo stuff continues to reminded me of...

    "are mindboggingly stupid animals,

    they assume that if you can't see them, they can't see you - daft as a bush, but very, very ravenous."

    Paris is also ravenous...

  49. Dave Roseblade

    why don't they...

    ...just use a prism to split the light so's some of it comes in to be viewed but the majority still cloaks? seems a lot simpler, especially if they use a compound prism like you get in the back windows of busses?

  50. John A Fotheringham


    ... this research is being done at the Unseen University?

  51. wayne

    Peep holes.

    You guys beat me to it, yes a peep whole, guess no patent for such an "unobvious" improvement to the invention . I do science fiction stories, and come up with a lot of fancy ideas and the peep hole is something I use for situations like this but with some improvements.

    A peep hole to relay an image can be so small that you don't notice it, think pin hole with an image sensor (like those security cameras). The peep hole can be made to emit a light spread that matches what people should see from the point anyway, with a matching hole on the other side to reproduce it's light (through interpolating and closing over the peep hole can also hide it).

    Another alternative is to let enough light through for a sensor (or the naked eye) to see but result in so little dimming in broad daylight that it is unnoticeable to the naked eye.

    A material can detect what hits and passes through it to those on the inside, and relay the information and reproduce the light where it should pass out the other sides. I do some innovation design, and have put some thought in techniques useful for this.

    Another option is that no light has to pass through at all, the photons can be detected before it is relayed and reproduced inside, and reproduced inside.

    Realistically, it will look wonky for some time as light is imperfectly bent around, or reflected (as in predator film).

    Wayne Morellini

  52. Anonymous Coward
    Anonymous Coward

    white-tiled battlefields ......

    .... veterans of which suffer from blindness and RSI, don't they ?

  53. Anonymous Coward

    The invisibility device

    has been in existence for years.

    As soon as I put my wife in her wheelchair, *nobody* can see her. Barstewards!

  54. Chris Cheale

    If it's on a tank...

    Right - you've got a tank with an "invisibility field" that bends radiation (visible light and heat).

    Surely you'd not actually need to "see" out with human eyes? Fit the tank with some "eyes" that read different information (sound waves, ultraviolet, infrared and so on) and convert that data into human-comprehensible images on monitors inside the tank?

    I assume I'm missing something obvious?

  55. Rob


    I have a volcano, is it your fault, if it is, THANKS

  56. Anonymous Coward

    A silly thought just occurred to me

    But could you do this with space-time? I imagine some weird crystal-like arrangement of interlocking massive cylinders spinning at close to the speed of light that forms a meta-material that bends space-time, rather like the shed-based stuff bends light, although presumably on a larger scale.

    You could then hide complete regions of reality. Put a planet inside one of those and you could pass right through it without even knowing it was there. Perhaps that's what God uses to cloak his engine-room (shed) out there in the universe, so we can't see him pulling the levers?

  57. mick

    floating eyes

    floating eyes, lol

  58. Jacob Lipman
    Paris Hilton

    A more realistic use...

    Realistically, having no practical purpose, if these metamaterials do eventually come into existence they will be relegated to the novelty aisle; like glow-in-the-dark materials, they'll be popular as decorations and on clothing. It'll be funny as hell to wander down the street as an apparently disembodied head, until everyone is used to seeing it and it ceases to be original. It will be used for pranks and fashion; perhaps eventually somebody will find the problem to which it is a solution, and the ludicrous amounts of money investing to develop the technology will prove not to have been entirely wasted.

    The metamaterials that bend visible light seem relatively worthless, but those that affect certain invisible bands could be very practical, namely, those used in radar. An even stealthier stealth bomber could result, maybe. Who knows, maybe early metamaterials are already in use on US stealth aircraft.

    Paris, because she looks good in invisible clothes.

  59. Taryn East

    @Jacob Lipman = a practical purpose

    Actually I imagine there might be any number of practical uses - but on a much csmaller scale than sheds or tanks. and more in the line of being a "better mousetrap"

    Your safe gets safer if the average crim can't see where it is (eg stuck to the ceiling then cloaked). I'm sure there are other potential uses like this.

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