invisible

[meredith101]

will it be possible to make things invisible? Can you see what I'm getting at?

[Llamatron]

Maybe.
And yes.

http://www.physorg.com/news67787896.html

[meredith101]

I'm disappointed that this question only received one reply.

[wildwood]

If you mean as in; spray my cup of coffee with a substance so I can't see it in front of me... no.

Like Llamatron's link, I firmly believe that we will develop the technology to cloak certain items in certain situation with light.
Similar technology has already been developed with sound by luxury car manufacturers where a microphone detects the car's (road)noise and replays it over the car's sound system at a certain micro time interval so to human ears it masks the noise.

In reality many things are invisible [to humans] such as certain levels of colour. Dust and microbes are not viewable without artificial assistance.

[Teddio]

To make something invisible it will have to be transparent (like glass) but it will also have to have the same refractive index as air. So of a solid object was transparent and had a refractive index of 1.0003 then it would be invisible,
If a glass beaker of refractive index 1,52 is placed in a colourless liquid of refractive index 1.52 then it would be invisible.

[meredith101]

cool thanks all, keep em coming. very interesting teddio.

This, from my old prof:

http://www.st-andrews.ac.uk/~ulf/invisibility. html

[JonnyBoy12]

Doctor, the invisible man is here to visit you!

Tell him I can't see him!

Seriously though all you have to do to be invisible is stop reflecting light. So no yellow high vis vests for you then. By the way you can't do it if you are a leopard......Because you'd be spotted!!!

[meredith101]

please do not work on any equivalent stripey jokes cos there are none.
I agree about not reflecting light. I think also that you notice things being there because they block out the background. I see a hill, I should see all of the light that has bounced off the hill that is coming towards me, but I can't, some of it is blocked, there is a cow that is blocking that light coming at me, so I know the cow is there. Not only can I see the light bouncing off the cow, I know I cannot see the light coming off the hill. If I can bend the light coming off the hill round the cow, it not only replaces the cow's light but makes the hill look like one 'piece', with no gaps. Thus...invisible cow.
Different scenario if it moooves

[mibn2cweus]

[mibn2cweus]

. . . D'oh!

[meredith101]

Nice answer, mibn2cweus, however I don't agree with the equation you use to transpose the light on a standard surface. Surely quantum effects of the photon, as you point out, would interact with the material making everything around it invisible?

[MatydaLover]

If someone says "there's an invisible object", then spit at it. You'll soon see.

You know something is there by its effect on its surroundings. To be truly invisible, the object would have to have absolutely no effect of any kind on anything - otherwise there would always be some way of detecting it. So invisibility remains a fanciful idea.

If the technicians produce a "cloak" it will only "work" in limited circumstances. You can always spray it red or something.

[meredith101]

if you cannot see an object, yet can hear it, and see it affect the ground, it is still inVISible

[ann_h]

DH's venerable ninjitsu master could make himself "invisible" using camouflage, unfeasible postures and trickery of that sort.

[Robb Phoenix]

I remember reading abt an invisibility cloak which takes images from behind you and projects it in the front rendering you invisible. (This cloak only makes you sort of transluscent but if the technology is perfected you could expect near transperency)