how to make objects invisible.

like cloaking device? Technologically we don't have that capability yet. Just recently some Japanese were able to invent some form of clothings that bends light around to give an illusion of semi-transparent person. But no true invisibility yet.

I seem to remember a chemistry teacher in high school filling a glass container with glycerine. Then he put another smaller glass container inside, and it was invisible. I believe it had something to do with the index of refraction :)

It was neat though. Did I remember this experiment correctly?

--buddy

(but do be a bit cautious with coasttocoastam.com's guests, some can seem perfectly normal for a while... and then suddenly spiral off into being full blown fruit loops)

You can also google for military camouflage fractal invisible I seem to recall reading something about using fractals to approximate invisiblity

The PBY (Patrol Bomber, Catalina), (used for hunting and killing submarines during WWII) had lights mounted on the leading edge of their wings. During daylight hours, they could get so close to subs without being noticed that the U-boats didn't have a change to dive and escape.

Well... I don't know if these are valid answers but...

This microdot --->

IIRC, what they really did was to dress the cloakee in retro-reflective clothing and project an image of the entire scene onto him. An old trick, really.

Hmm..dunno if you're referring to the same thing, but I've seen one where they cover "invisible" surface with a matte, reflective material. There is a camera just on the other side of the object filming its background and a projector in the foreground superimposing that image on top of the scene. The net effect is that the object is very hard to see from a particular angle. There are some videos online which demonstrate some funny visual effects.

Also, ships were painted with bizarre patterns. When seen at a distance on the ocean, the human eye/brain combo rejects the pattern as not what is expected. This renders the ship "invisible."

Al

We can REDUCE visibility but not make most things (solids- liquids) truly invisible. Just like stealth technology. These do not make aircraft truly 'invisible' to radar, only greatly reduce their detection range.

One problem is that even a transparent material (such as glass) which has an index of refraction greater than air (virtually all solids have an index considerably greater) still creates some reflections at the air/solid interface. So even if an object is truly transparent, you will see some reflection and background refraction, especially in strong sunlight.

Truly strong absorbers as used in radar do NOT work, as the result is you see a flat black object standing out against a visible background.

hard way: if you have a little exotic matter and control of matter at the planck scale, stick your object in a spacetime bubble.

easy way: remove object.

Don Taylor wrote in news:W8OdnWuy_49v__feRVn- snipped-for-privacy@scnresearch.com:

put it in the closet...?

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Yes! I do it all the time! Believe it or not, use lights!

On 3 Nov 2005 07:56:07 -0800, "ryadav" scratched with their pencil:

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Adam Hart-Davis on the BBC, once mounted a lot of those LED-based outdoor display screens, on one side of a car. On the other side, a camera, and the effect, as seen on television, was actually pretty impressive.

If you hadn't been looking for it, it *might* have fooled you.

So the answer is, yes, in very limited conditions. Similarly magicians make things "disappear" from certain angles.

But for practical purposes, no, not yet. Perhaps OLED clothing will one day do the trick.

------------------------------------------------------------------------

if love is a drug, then, ideally, it's a healing, healthful drug... it's kind of like prozac is supposed to work (without the sexual side effects and long-term damage to the brain and psyche)

Stare into the sun. :) It's possible to make objects almost invisible from one direction by covering them with a display that shows an image of what is behind them. but viewed from a different angle the image won't line up with the background.

There is a line of research where an object is covered in a flexible screen which is wired to a camera. A person looking at the screen would see the image of what's directly behind and completely cover anything between the two and making it appear invisible. The technology hasn't yet been perfected, but its a working prototype.

Graham

Yes... under certain conditions.

screen

Not quite. The "background" will appear to be the wrong distance from the observer.

Hitchhikers' Guide to the Universe -- to make something invisible, make it someone else's problem. ;-)

Cheers Chris