Name: 物理学者がハリーポッターの「透明マント」は実現可能かを解説 | WIRED JAPAN
Uploaded: 2025-02-13T09:46:22.000Z
Duration: 8 min 24 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

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 Kramer, 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.

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 right now, 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 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 kind of 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 thinness that we're working with on all the other applications out there.

It's still kind of like distorted, right?

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 going to 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.

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 goes 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, that's the person or the thing that you want to hide, it's going to 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 going to 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 if 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 kind of 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 think it will ever really be possible to do it at wavelengths that we can see?

The plain 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 to it, 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 going to 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, it's a challenging project, because now you're not just collecting a single ray, you're collecting all rays from all directions.

Right, right, because 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, and how do you emit in a given direction and position for every ray?

But once you've solved that problem, then you have invisibility.

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

I would label that as a broadband, omnidirectional invisibility cloak.

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's background remains undisturbed.

Thank you so much for being patient with us and answering all of our questions.

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物理学者がハリーポッターの「透明マント」は実現可能かを解説 | WIRED JAPAN

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