Is Invisibility Possible? An Inventor and a Physicist Explain

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[Narrator] There's a new material

that's been attracting a lot of attention online.

It's being called an invisibility cloak,

you know, as in Harry Potter's.

But it's not magic that's hiding these objects from view.

Made for military applications,

the thin bendable plastic sheets

lined with a series of lenses

are 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 could

not only hide you in any environment,

but also mask your movement behind

whatever it is that ended up becoming the solution.

What is it and kind of, how does it work?

It's off the shelf material.

The light is being bent left and right

as you're looking through it,

and so what you're actually seeing

is what's behind me on both 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 the invisibility becomes.

Can you walk me through kind of like,

the best way to use this prototype?

So version one, we simply put on a riot shield,

and so it's just one piece of the material

with the flat back and we've just affixed it

to the riot shield there,

so if I hold it up, and [mumbles]

Wow, that's pretty impressive.

[mumbles] the distance is not that far away,

and the farther I hold it, the better it is,

and the closer I hold it, the worse it is.

That would be one simple application for a tactical team

going into a bad hostage situation.

The version two material is here,

and you can see that

there's a little blurry section in the middle

and I can manipulate that right now,

and I can get this actually quite a bit closer to me

than I can with version one,

so it's about half the distance for this to be effective.

How do you envision it being used in the battlefield?

I believe at some stage, we will figure out

the principle of what you're seeing there

and manipulate that material into something

that can go into a parachute-type material

or a clothing-type material.

If it's in a parachute,

then a sniper could repurpose it

once he lands on the ground,

and turn it into a sniper hide or even a poncho,

can actually utilize that lens large-scale

to hide a tank or a building

and still have that thin-ness that we're working with

on 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 knows

that someone has come into the room,

if you're using that riot shield or something like that.

Do you think you'll ever get to the point

where they're just totally surprised

or that humans really can't see what's going on?

We're not trying to pull the wool

over people's eyes with this.

We're trying to show them,

this is the reality of the prototypes

and what we have using off-the-shelf material.

Given manufacturing, we're gonna be able

to manipulate those areas that are hiding the target

and reduce the areas that are causing

the enlargement of the target.

Will we achieve full invisibility with this?

I can't say yes or no,

but we can achieve something that is close enough

that it would be sufficient for combat use out there.

We wanted to find out more about the science

behind this material, so we called up Dr. John Howell,

a physicist and specialist in quantum optics

who has studied making the visible invisible.

He says this technology is more about cloaking,

like ships in Star Trek, than true invisibility.

They have the cloaking device.

So what do you think of the invisibility cloak?

First of all, I think it's fun 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 doing optical camouflage.

When I think of cloaking, what I mean is

you see the background undisturbed

but whatever you're trying to make invisible

is in front of that background.

A lot of illusions were basically making you think

you're looking at something that you're not.

For example, you have sunlight coming down.

You put it through a lens and 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 a point, they come to a line,

so if you have light go through a cylindrical lens,

it comes to a line, it goes to a focus,

and then it starts to diverge.

A lenticular sheet is an array of cylindrical lenses,

and now what you've done is

you have light scattering off a person, you know,

that's the person or the thing that you want to hide,

it's gonna go towards the observer,

but when it hits that lenticular sheet, it diverges.

You still are going to get light from the object,

you're just gonna get a lot less light from the object,

but it's how it's moving that light around

and if you don't want to see something

or you want to hide something,

you simply just make it

so light rays that are coming from the object

are 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 able

to do cloaking with some wavelengths,

but do you ever think it will ever really be possible

to do it at wavelengths that we can see?

Can you get cloaking?

Answer is yes,

and there's a very simple way of thinking about it.

So now if I take a light ray,

and then I add one other element which is

I know the wavelength, I know its direction,

and I know its position,

then I can calculate where that line will be

at any future time and be able to predict it,

so now let's suppose I take a measurement over here,

I determine a position, a direction,

and a color for a light ray,

and then I say okay mathematically I know at this point,

I know it's gonna be coming this direction,

so I know when it gets over here, it should be doing this.

So if I can get all that information and then send it,

send all of the information out at this point,

I've been able to recreate that light ray,

so it really comes down to how well can you measure it

and how well can you emit it.

Why don't we have an invisibility 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 all rays from all directions.

Right, right, 'cause you're not just,

you have to know so much about,

you could probably make maybe an invisibility device

for a certain room where you control the lights

or something like that,

but it would be harder to do it in a changing environment.

But it then becomes a really challenging,

how do you determine the direction or position of every ray,

how do you emit

in a given direction and position for every ray,

but once you solve that problem, then you have invisibility.

You know, the classic is Harry Potter's cloak.

[Filch] You can't hide.

I would label that

as a broadband omnidirectional invisibility cloak,

and what that means is that

it has to work over the entire wavelength

that our eyes work and it has to be,

no matter what direction you view it,

you want to have it so that Harry Potter is not visible

and 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 for being patient with us,

and answering all of our questions.

This is really, really fascinating.

Good luck with things.

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