Are cloaking clothes physical feasible?

Question

Cloaking clothes are used by Harry Potter to make himself invisible.

I have been thinking about the physical feasibility of such clothes. Would it be possible to actually make one? It has to redirect the light that falls on every side of me to the opposite side so it looks to someone looking at me if I'm not there.

I've been thinking about sensors in the clothes and internal (to the clothes), light and small computation devices to make this happen. The problem is obvious. The clothes move in unpredictable ways and have a huge variety of different forms. On top of that, there has to be communication between all opposite sides of the 2-dimensional surface of the cloaking mantle. There are zillions of photons coming in from all sides. It's very complicated.

Would it be feasible?

Answer 1

Something similar to an invisibility cloak has been demonstrated by a Canadian company

From Athena’s cap of invisibility to H.G. Wells and Harry Potter, the notion of making oneself invisible has always tickled human fantasy. Incredibly, technological advancements over the last few years have brought these fantasies into the real world.

The latest invisible tech, called Quantum Stealth, has been developed by Hyperstealth, a Canadian camouflage design company. The material is as thin as paper, inexpensive, and requires no power source. While it doesn’t work quite as well as a magical cloak, it does a pretty good job of concealing and is certainly confusing to look at.

The material uses an approach that you might already be familiar with: lenticular lenses. If you have seen one of those pictures that appears 3D depending on how you look at it, you have seen this tech.

In a similar manner, the material can bend light in a way that means only things very close or very far away can be seen. So an object or person placed behind it at a certain distance will become invisible. The material has quite the broadband capability and is able to bend light from mid- and near-ultraviolet to the infrared. Given the lower resolution of cameras that work outside the visible light spectrum, the effect becomes a lot more pronounced and remarkable when the material is viewed through them.

The material is not affected by the colors of what it's trying to conceal but it does distort the background. So it's not a magical invisibility cloak; people will know that something is hidden behind it, they just won’t be able to discern the details of what it is.

Answer 2

Is it theoretically possible? I'd say yes.

As @ldutch points out, a prototype of such a device has, in fact, been made. I read an article about such a device, I'm not sure if he's referring to the same device or a different, similar one, but whatever. The principle is straight forward enough: put what amounts to a bunch of video cameras on the device that feed video displays on the opposite side. So that whatever is behind the object, from whatever perspective, is displayed in front. Of course I'm using the word "camera" here loosely. Each "camera" is a single sensor controlling one pixel. In a sense the whole device is one big camera.

It's probably technically simpler if you make it a solid cylinder. Then the mapping from "back" to "front" is simple and constant. To make an actual "cloak", yeah, you have to deal with the movement and folding and so forth of the material. It would take a bunch of sensors and a huge amount of computation. But is that fundamentally impossible? I don't see why. Once you got all the details worked out for one pair of camera and display, you just replicate that for all the hundreds or thousands of cameras.

Like many inventions, it's a long way from "basic idea" to "working prototype", and even further to "practical working model". Further still if you want to get to "can be mass-produced at a reasonable cost".

If the video camera idea doesn't work out, I've heard other ideas. Years ago I read about an idea to make an invisibility cloak by bending light around the wearer using a bunch of mirrors and lenses. That sounds more complicated, but maybe if someone had a brainstorm they could make it practical. Or maybe some totally different technology.

Answer 3

Yes, but the tech you are describing is very advanced

Let’s list the needed tech for this to work:

360 degree programmable lights that can be customized to change the light shown at each angle down to less than a degree. They must have a refresh rate of over 200 times a second. They must also be non reflective.

A surface that can determine its position down to a millimeter with a refresh rate of over 200 times a second.

Paint on the surface the lightbulbs are on that absorbs all light, this does actually exist.

An easy way to clean this since dirt will be noticeable, and the light bulbs need to be cleaned occasionally.

Either trillions of cameras or dozens of cameras and an advanced algorithm to interpolate the footage using photogrammetry.

The hardware to run either the basic math or the hard math shown above.

A power source dense enough to power this that can be varied by the person.

All this in a form factor that people can move in at a weight that people can move with.

Any changes to this will reduce effectiveness, to the point where the lenticular lens will be just as effective but less costly.

Answer 4

No

Projectors

Let's start with a hypothetical situation: There is a cylinder. It has cameras on all sides to project the image it takes up to the other side. So if you watch at the item face on, it blends into the surroundings.

Now, make a step to the side. The projection to that face does not line up with the image behind it and is immediately obvious because it can only project to its surface the light that would fall through its center axis - but you'd need the light that does not pass through that axis.

Lenses

Using lenses, you can't achieve total success either: to be invisible by light being refracted around you, the lens can at best cover half the body - any more and it will show the lenses on the backside. Then those lenses also only work when looked orthogonally onto them - again, if you look at the thing from the wrong angle, you see it. Then, it very much distorts the background, and any natural background makes that very visible. And last but not least: your object needs to be a certain distance from the lens. Which is quite large: to hide a 10 cm car model, you need about 10 cm from the car to the lens screen. To hide a 50 cm wide human, the shield needs to be about as far from the body.

This makes Lenses not an option for an invisibility cloak, and as a screen, they are totally obvious about their presence. They might hide what is there, but not that something is there - a huge fail.

Extra: different wavelengths are refracted differently. These lenses don't obscure the object to an infrared or UV camera in the same way.

Answer 5

Yes

Many different methods have been tried in the last couple decades, with varying degrees of success. The latest one comes from Canadian company Hyperstealth. As I type this I see that Dutch ninja'ed me, so to add to his post I am leaving here a link to their patent application.

And here is a 4 minute video on Youtube demonstrating the cloaking material in practice.