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How to Become Invisible
mdm42 writes "Looks like a theoretical physicist at St. Andrews University in Scotland believes that invisibility may be possible. And its not going to be a potion or a cloak, but will come in the form of a device. " Let's just hope that when the invisible woman arrives, she's played more convincingly than Jessica Alba.
All it takes is a suitably large gravity well. Black holes have been doing this since the dawn of time.
But seriously, all the new light bending materials I've been reading about look neat, but seem to be focused on certain wavelengths. Broad spectrum invisibility will likely be pretty tough.
If a device is made to either redirect light, or detect light in the environment, absorb it and then project light to match it, then there will be some delay necissary in the process, because you can't send out information before you observe it.
Don't know how significant it would be, but that could result in a slight disjointed projection of the area behind you if you were made 'invisible' with such a device, most observable when one moves.
Thus, the more apt movie reference would be Predator.
Ryan Fenton
true invisibility is impossible
Not really. It can be done and probably will be done some day. It is just not as simple or work the same way bad sci-fi shows portray it.
and even if it was possible, we'd be blind while we were invisible.
Yes, but this is a solvable problem as well. Bend visible wavelengths of light around, but not infrared and wear infrared goggles. Or bend light around everywhere except a pinhole too small to be visible, but which is used to generate a view outside the cloak like a pinhole camera does. Or transmit an image from a small device outside the cloak. The hard part is redirecting the light properly. Once that is solved, the rest is a lesser problem.
I wonder if this is BadAnalogyGuy in disguise? :)
A most people will have actually seen water flowing around a rock in a creek or a stream will attest, the water doesn't just leave as if nothing was there: there's all sorts of turbulence, especially leaving visibile waves on the surface and even a trail of bubbles if there is sufficient flow to cause aeration.
Of course, if you bend all light around you, there's no light hitting your eyes. That's BTW also the main fault of the invisibility concept in movies and stories: The people get completely invisible, but they can still see just like normal. But to see like normal, the light has to be fist bent by your eye's lense, and then absorbed by your eye's retina. Which should make at least your eyes visible quite well. Of course that's no problem with magic (magic can override all laws of nature anyway), but it's clearly a problem if the invisibility shall be achieved by a physical effect.
The Tao of math: The numbers you can count are not the real numbers.
"I'm invisible!" convincingly enough.
Actually, speaking isn't required. The actual technique is waving your hands in front of you and then snap your fingers.
Of course, it doesn't work when you're wet.
Mutual Assured Destruction has kept the nuclear powers-that-be in check for 60 years. A country that feels it has the technology to intercept incoming missles, and massively surprise its enemy (using stealth as discussed in this article), ... well that country might just decide it has to strike first, before its enemy achieves similar capabilities and makes the same judgement call.
Think about it. Your military advisers tell you that 1) you can intercept incoming missles (even from subs), and 2) deliver missles without being detected. In essence, they are saying you could launch a preemptive nuclear strike with mostly political, not military, consequences.
You are also advised that in a few years your enemy will have sufficient tecnology to do the same.
Suddenly M.A.D. is out the window, and replaced with a "whomever strikes first wins" scenario.
Put three guys in a room (U.S., China, Russia) blindfolded. Tell them the first that leaves the room will live, and the rest will die, but if they all stay put, they will all live. Then tell them there is unlimited power for the first one out the door. What do you think will happen?
Even if you don't pass IR into the invisibility field, there's still likely to be detectable elements of the heat signature or other items radiated/expelled from the cloak that it still wouldn't render you undetectable. Ie, if I made a vehicle visually invisible its still likely to emit exhaust or a big EMF field from electric motors, people breathe, exhaling heat and CO2, etc.
"Invisibility" as defined as not providing a reflected-light image is the least significant part of the problem without also providing some way of eliminating other physical detection. It might be useful if you were cloaking a sealed, inanimate object that had no EMF or other signatures detectable, but I'm not sure it'd be cost effective against other low-tech methods for simply hiding something or otherwise camouflaging it.
What if only her clothes are made invisible?
Could tanks still fire their weapons if coated in this?
Come on lad, Birds of Prey cannot fire when they are cloaked. That's Trek 101, basically.