Skip to main content
U.K. Edition
Sunday, 17 January 2021

Is Invisibility Possible? An Inventor and a Physicist Explain

Credit: WIRED
Duration: 08:24s 0 shares 1 views
Is Invisibility Possible? An Inventor and a Physicist Explain
Is Invisibility Possible? An Inventor and a Physicist Explain

Videos of a new product being called an invisibility cloak recently surfaced online.

WIRED's Louise Matsakis spoke with its inventor and a physicist who studies optics to find out how it works and whether cloaking and invisibility are truly feasible.

[electronic music]- [Narrator] There's a new materialthat's been attracting alot of attention online.It's being called an invisibility cloak,you know, as in Harry Potter's.But it's not magic that'shiding these objects from view.Made for military applications,the thin bendable plastic sheetslined with a series of lensesare specially designed to obscure objects,like a soldier or a tank.We wanted to find out more,so we called up Guy Cramer,one of the founders of HyperStealth,the company that makes it.- The pinnacle of camouflage,we knew going into this,was going to be something that couldnot only hide you in any environment,but also mask your movement behindwhatever it is that endedup becoming the solution.- What is it and kindof, how does it work?- It's off the shelf material.The light is being bent left and rightas you're looking through it,and so what you're actually seeingis what's behind me onboth sides and on an angle,so the light comes out and it does this,and it creates this dead zone in the back,so the further back I am,the more impressive theinvisibility becomes.- Can you walk me through kind of like,the best way to use this prototype?- So version one, we simplyput on a riot shield,and so it's just one piece of the materialwith the flat back andwe've just affixed itto the riot shield there,so if I hold it up, and [mumbles]- Wow, that's pretty impressive.- [mumbles] the distanceis not that far away,and the farther I holdit, the better it is,and the closer I hold it, the worse it is.That would be one simpleapplication for a tactical teamgoing into a bad hostage situation.The version two material is here,and you can see thatthere's a little blurrysection in the middleand I can manipulate that right now,and I can get this actuallyquite a bit closer to methan I can with version one,so it's about half the distancefor this to be effective.- How do you envision itbeing used in the battlefield?- I believe at somestage, we will figure outthe principle of what you're seeing thereand manipulate thatmaterial into somethingthat can go into a parachute-type materialor a clothing-type material.If it's in a parachute,then a sniper could repurpose itonce he lands on the ground,and turn it into a sniperhide or even a poncho,can actually utilize that lens large-scaleto hide a tank or a buildingand still have that thin-nessthat we're working withon all the other applications out there.- It's still kinda like distorted, right?And like you said, there might be a delay,but the target or whatever knowsthat someone has come into the room,if you're using that riotshield or something like that.Do you think you'll ever get to the pointwhere they're just totally surprisedor that humans reallycan't see what's going on?- We're not trying to pull the woolover people's eyes with this.We're trying to show them,this is the reality of the prototypesand what we have usingoff-the-shelf material.Given manufacturing, we're gonna be ableto manipulate those areasthat are hiding the targetand reduce the areas that are causingthe enlargement of the target.Will we achieve fullinvisibility with this?I can't say yes or no,but we can achieve somethingthat is close enoughthat it would be sufficientfor combat use out there.- We wanted to find outmore about the sciencebehind this material, so wecalled up Dr. John Howell,a physicist and specialistin quantum opticswho has studied makingthe visible invisible.He says this technologyis more about cloaking,like ships in Star Trek,than true invisibility.- They have the cloaking device.- So what do you think ofthe invisibility cloak?- First of all, I think it'sfun to watch and it's clever,and I think it has a lot of practical use,but its definition as a cloak here is not.It's a good way of doingoptical camouflage.When I think of cloaking, what I mean isyou see the background undisturbedbut whatever you'retrying to make invisibleis in front of that background.A lot of illusions werebasically making you thinkyou're looking atsomething that you're not.For example, you havesunlight coming down.You put it through a lensand you look at the ground,you see it come to a sharp focal spot.In a cylindrical lens,they're long and they're skinny,and instead of coming to apoint, they come to a line,so if you have light gothrough a cylindrical lens,it comes to a line, it goes to a focus,and then it starts to diverge.A lenticular sheet is anarray of cylindrical lenses,and now what you've done isyou have light scatteringoff a person, you know,that's the person or thething that you want to hide,it's gonna go towards the observer,but when it hits thatlenticular sheet, it diverges.You still are going toget light from the object,you're just gonna get a lotless light from the object,but it's how it's moving that light aroundand if you don't want to see somethingor you want to hide something,you simply just make itso light rays that arecoming from the objectare sent to different locations.- This is more of an existential question,but do you think it's really possible?It sounds like researchers have been ableto do cloaking with some wavelengths,but do you ever think itwill ever really be possibleto do it at wavelengths that we can see?- Can you get cloaking?Answer is yes,and there's a very simpleway of thinking about it.So now if I take a light ray,and then I add one other element which isI know the wavelength,I know its direction,and I know its position,then I can calculatewhere that line will beat any future time andbe able to predict it,so now let's suppose I takea measurement over here,I determine a position, a direction,and a color for a light ray,and then I say okay mathematicallyI know at this point,I know it's gonna becoming this direction,so I know when it gets overhere, it should be doing this.So if I can get all thatinformation and then send it,send all of the informationout at this point,I've been able to recreate that light ray,so it really comes down tohow well can you measure itand how well can you emit it.- Why don't we have aninvisibility cloak now, then,if it's possible?- Engineering is a challenging project,because now what you're not,you're not just collecting a single ray,you're collecting allrays from all directions.- Right, right, 'cause you're not just,you have to know so much about,you could probably makemaybe an invisibility devicefor a certain room whereyou control the lightsor something like that,but it would be harder to doit in a changing environment.- But it then becomesa really challenging,how do you determine the directionor position of every ray,how do you emitin a given direction andposition for every ray,but once you solve that problem,then you have invisibility.You know, the classicis Harry Potter's cloak.- [Filch] You can't hide.- I would label thatas a broadband omnidirectionalinvisibility cloak,and what that means is thatit has to work over the entire wavelengththat our eyes work and it has to be,no matter what direction you view it,you want to have it so thatHarry Potter is not visibleand the background remains undisturbed.That's the holy grail of invisibility.Can it be done?I hope so.I think it would be fun to do.- Thank you so much forbeing patient with us,and answering all of our questions.This is really, really fascinating.- Good luck with things.

You might like