Invisibility cloaks!

[Asterion]

kids would be able to hide their drugs a little more effectively, violent gangs would be able to hide weapons, or even conceal them out in the open. Someone could be carrying around a minigun and you might not know it. Divers could get closer to fish, and keep clear of sharks and other dangerous animals, and same for on land, photographers could easily sneak up on that gorilla and take as many photos as they like. Laser tag and paintball just might become a very difficult sport. You could trick people into thinking that you lost all of your teeth in that fight you just got into, or after you stack your bike, you could trick others into thinking that it tore off your arm. it could cover up any details of your face that you don't want others to see... and leave them with gaping wholes. You could pickpocket, loot and be a menace to the rest of the world and noone could stop you.

I'm starting to think that this could be a really bad change, the police would never let people buy them, especially since you could avoid getting your car defected, hide an explosive anywhere, or even hide a drug lab... almost... sense of smell would become an issue there though.

edit: oh, and thermal vision would shatter this ideal in an instant.

 

[BlueGray]

How would thermal vision shatter an invisibility cloak? That's still radiation, just of a different wavelength.

 

[redacted]

How would an invisibility cloak be feasible? You could do it to one stationary person, but anyone else looking would see really weird shit. Or if the observer moved, they would see weird shit. Unless it was locked on to the position of their eyes...but it would still only work on one person.

 

[nozflubber]

1st of all, NOTHING is entirely "invisible" in the electromagnetic spectrum. Anything with a thermal energy of 1 kelvin or more will emit infrared radiation. This is an unmovable law.

The trick would be to emit nothing in the EM spectrum that humans can see, 400-700 nm wavelength light. This is particularly difficult as just about all matter emits this in one form or another. I think if you could somehow create a layer that converted all visible EM radiation into "non-visible" (again thats not literally true) light, then you might have a feesible cloak.

 

[nozflubber]

Um . . . but if you're looking for serious, practical uses, I suppose it'd be a great help in the military.

the thing is that it wouldn't. Infrared radiation equipment is the norm nowadays in military gear and vehicles. Trying to hide a tank with an cloak that masks 400-700nm radiation wouldnt do a hell of a whole lot as the thermal energy coming out of the thing still makes it bright as hell to infrared, which is standard on aircraft designed to destroy tanks and artillery. Even snipers and Target PAinters are often given IR scopes to check for camouflaged gunmen and concealed equipment, so I don't even see it being useful for concealing a sniper, or anything really.


The only useful application of this would be Hide and Go seek games, or masking a door or opening to a building. Or someone fleeing from the cops as they don't ever use this kind of equipment.

and as fluffy pointed out, there's a problem with entire objects Disappearing within a person's visual field. People are likely to notice a big black "glob" missing from the spatial environment. Filling in for it adequately would be tough.

 

[StrappingYoungLad]

The closest thing to invisibility cloaks that I've seen was a japanese dude wearing a shirt that had on the front side a projected image captured from a camera from his back. Even though the quality was rubbish, the effect was still über awesome.

 

[redacted]

1st of all, NOTHING is entirely "invisible" in the electromagnetic spectrum. Anything with a thermal energy of 1 kelvin or more will emit infrared radiation. This is an unmovable law.

The trick would be to emit nothing in the EM spectrum that humans can see, 400-700 nm wavelength light. This is particularly difficult as just about all matter emits this in one form or another. I think if you could somehow create a layer that converted all visible EM radiation into "non-visible" (again thats not literally true) light, then you might have a feesible cloak.

That still wouldn't work unless other light waves could move through your body without bending (or disappearing). Otherwise you'd just be a giant black spot.

The only thing I could see working (for only one person) would be a suit of little display screens and cameras. Each display screen would show an image dependent on the position of the observer and the cameras on the other side of the body in a direct line from the observer to the display screen. As the position of the observer changes in respect to the person wearing the cloak, the display on each screen would change.

The cloak would need some sort of targeting to lock on to both eyes of the observer though. And two observers wouldn't be possible.

 

[redacted]

Ugh, I forgot there's the underconstrained inverse problem of distance to an object. Is it close and small or far and big?

So there would need to be two separate trackers for the observer, one further than the other, to account for how large to make the image on the screens.

 

[Asterion]

How would thermal vision shatter an invisibility cloak? That's still radiation, just of a different wavelength.

I was assuming that this theoretical cloak would be blocking/transmitting the visible spectrum only.

Ugh, I forgot there's the underconstrained inverse problem of distance to an object. Is it close and small or far and big?

So there would need to be two separate trackers for the observer, one further than the other, to account for how large to make the image on the screens.

yes yes, so it might work a little bit, all new technologies start out flawed anyway. The thing is, would a flawed invisibility cloak be more usefull than simply trying to blend in with your surroundings? ... what was this thread about...

add: if it blocks out other spectrums, even if it leaves a black spot, it might be pretty useful.

 

[nozflubber]

^ i was thinking that too. In certain already- dark conditions, the cloak could be very effective. But in full sunlight it would stick out like a sore thumb

 

[InvisibleJim]

I already have one.