# Is invisibilty a physical impossibility? **URL:** \ **Category:** Factual Questions\ **Created:** [August 23, 2001, 1:11pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712 "2001-08-23T13:11:52Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Superdude](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/superdude/32/13450_2.png) [@Superdude](https://boards.straightdope.com/u/Superdude)\ **Post date:** [August 23, 2001, 1:11pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/1 "2001-08-23T13:11:52Z")
I understand how certain things are invisible to the naked eye (radio waves, etc.). And that certain things are invisible to radar (the stealth bomber). But is it physically possible to render one’s self invisible to visual detection? A la the old Claude Raines movies, and mad scientist plots? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 23, 2001, 1:48pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/2 "2001-08-23T13:48:19Z")
Even if you were able to remove all pigment and opacity from your body, the fact that it’s made mostly of water would render you visible. I’ve read a few SF stories where something was rendered invisible by virtue of it being ‘a colour that lies outside the visible spectrum’ and although this is an interesting literary device, it has no sound basis in reality; colours outside of the visible spectum (i.e. that don’t reflect any visible frequencies) would look black. Then there’s the idea of bending the light around something so that light from objects behind it still reaches the observer; tricky as you need to straighten out the light again and point it in exactly the direction it _would have been_ travelling if you weren’t in the way. And finally there’s mental manipulation, probably the most achievable (but still fairy dust at the moment) - human perception occurs in the brain/mind, so all you need to do is trick the mind into not seeing something (don’t worry about it not being able to see what’s _behind_ the hidden object; the mind is quite good at sketching in details of it’s own accord) - a bit like when you searched and searched for your car keys and they were right there in plain sight; you even looked at them, but you didn’t ‘see’ them. ---
**Author:** ![micco](https://avatars.discourse-cdn.com/v4/letter/m/5f8ce5/32.png) [@micco](https://boards.straightdope.com/u/micco)\ **Post date:** [August 23, 2001, 1:56pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/3 "2001-08-23T13:56:02Z")
“Impossible” is not a word to bandy around lightly, so I’d say no, it’s not impossible. I can imagine a suit using fiber optics or somesuch that would collect ambient radiation and re-emit it on the opposite side in exactly the right angle so that the suit appearred to be transparent. I don’t know how you’d go about building it, but I can imagine it and the rest is technical detail. Also, there was a news item recently about a doctor who had made a solution which could be injected into a patient and it would temporarily make a small patch of skin transparent. This was being proposed as a surgical and diagnostic assist. I don’t remember whether it affected muscle, but it certainly didn’t affect bone, so it’s not a general solution, but it shows incremental progress. The article is referred to here: > **[The Invisible Man? Kinda. - Slashdot](https://slashdot.org/story/00/08/23/1550248/the-invisible-man-kinda)** > > A lot of people have written in regarding the announcement from scientists at the University of Texas @ Austin discovering "invisibilty". Well, sort of. What it does do is make small areas of skin (humans have not been tested) transparent for a... but the actual article has disappeared into the non-free archives of the Houston Chronicle. My biggest problem with most of the sci-fi representations of invisibility is that the invisible guy can see normally (or with slightly tweaked toaster effects). If your retina is invisible, you’re blind. ---
**Author:** ![Ottoerotic](https://avatars.discourse-cdn.com/v4/letter/o/6de8d8/32.png) [@Ottoerotic](https://boards.straightdope.com/u/Ottoerotic)\ **Post date:** [August 23, 2001, 2:23pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/4 "2001-08-23T14:23:03Z")
Even if you used fiber optics, they still dim the light a little. So at best you could become a moving shadow. ---
**Author:** ![micco](https://avatars.discourse-cdn.com/v4/letter/m/5f8ce5/32.png) [@micco](https://boards.straightdope.com/u/micco)\ **Post date:** [August 23, 2001, 2:56pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/5 "2001-08-23T14:56:41Z")
> [@](#): > > \*Originally posted by otto3883 \* > \*\*Even if you used fiber optics, they still dim the light a little. So at best you could become a moving shadow. \*\* So add inline boosters just like the ones used for transmission on long cables. I’m not saying it would be easy and I’m skeptical (even pessimistic) by nature. I’m not even saying that my off-the-cuff scheme it the most practical. But to say a minor technical detail like fiber loss makes the idea impossible is similar to the Wright brothers’ claim that no airplane would ever cross the Atlantic because no engine could run for four days without stopping. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 23, 2001, 3:08pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/6 "2001-08-23T15:08:15Z")
the biggest hurdle on the way to this fibre-optic suit thing is going to be getting the all of light to resume travelling in exactly the direction it was when it hit the suit, plus getting it to exit the suit at the precise point at which it would have passed through if there was nothing in the way. No, I’m going to stick my neck out and say that for moving objects (where the suit will have to flex and bend, as well as the motion/rotation of the body parts), a fully functional fibre-optic suit would and will be a practical impossibility. now for ordinary camouflage, it might work, especially if the background is broken/random anyway, like jungle or soil - in this case, it’s general pattern and colour that would be effective. ---
**Author:** ![Tretiak](https://avatars.discourse-cdn.com/v4/letter/t/a88e57/32.png) [@Tretiak](https://boards.straightdope.com/u/Tretiak)\ **Post date:** [August 23, 2001, 3:14pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/7 "2001-08-23T15:14:11Z")
Wouldn’t that kind of suit either a) be incomplete where your eyes would be or b) not allow the wearer to see? I mean the light coming into your eyes is needed by your eyes to see. The whole eye thing is why invisivility always seemed far-fetched - more so - to me. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 23, 2001, 3:17pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/8 "2001-08-23T15:17:28Z")
> [@](#): > > \*Originally posted by micco \* > \*\*But to say a minor technical detail like fiber loss makes the idea impossible is similar to the Wright brothers’ claim that no airplane would ever cross the Atlantic because no engine could run for four days without stopping. \*\* This analogy is useful in that it prompts us to keep an open mind, but we should be wary of applying it to the extreme that we will accept that _anything at all_ will be possible at some point in the future, for example: “It’s not possible for me to travel to the moon using only a bathtub and a trampoline” “Ah yes, but that’s what they told the Wright brothers” ---
**Author:** ![bup](https://avatars.discourse-cdn.com/v4/letter/b/6bbea6/32.png) [@bup](https://boards.straightdope.com/u/bup)\ **Post date:** [August 23, 2001, 3:29pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/9 "2001-08-23T15:29:20Z")
They’ll figure out cloaking devices long before there’s a warp drive. It’s just a big, complicated information problem. It would probably be easier to be invisible if you had the caveat that it was from one viewer’s perspective, and you got to say they have to stand some distance away, so the light ‘coming from behind you’ all has to travel the same direction for the illusion. ---
**Author:** ![micco](https://avatars.discourse-cdn.com/v4/letter/m/5f8ce5/32.png) [@micco](https://boards.straightdope.com/u/micco)\ **Post date:** [August 23, 2001, 4:11pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/10 "2001-08-23T16:11:56Z")
> [@](#): > > \*Originally posted by Mangetout \* > \*\*This analogy is useful in that it prompts us to keep an open mind, but we should be wary of applying it to the extreme that we will accept that _anything at all_ will be possible at some point in the future, \*\* I agree completely. You just have to decide what’s extreme. I’ll agree with you that it would be exceedingly difficult to get to the moon with only a trampoline and a bathtub. “Impossible” is likely enough there that I’d put my smart money on it. However, I wouldn’t think invisibility is quite so extreme. You discount my scheme based on what I consider to be mere technical details (signal loss, broadcast angle, etc.). You’re welcome to draw the “impossible” line wherever you like, and I’ll grant you that my scheme was an offhand comment, not a working plan. However, I know some guys who are very good in optics and some others who are very good in MEMs. If they put their heads together, they could probably make an invisible box by the end of the week (oops, already Thursday…). A box is a long way from the fabled magic cloak of invisibility, but surely you’d allow for incremental progress. I’ll see your rebuff of my Wright Bros. cliche and raise you another: Technology far enough advanced is indistinquishable from magic. We’ve made flying carpets and lightning bolt wands, so surely cloaks of invisibility are just a few MIT senior pranks away. ---
**Author:** ![psychomonkey](https://avatars.discourse-cdn.com/v4/letter/p/dec6dc/32.png) [@psychomonkey](https://boards.straightdope.com/u/psychomonkey)\ **Post date:** [August 23, 2001, 4:25pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/11 "2001-08-23T16:25:03Z")
First off, if the learning channel is to be believed, the goverment is already working on the fiber optic suit, and making some progress. Apparently, it looks sort of like the “heat waves” one sees in the desert or on asphalt. Second, I’d be willing to agree with Tretiak, the light going into your eyes needs something to projecton to, and if your retina is invisible, it can’t absorb the light to be turned into electrical signals, in other words, even if it were possible, you couldn’t see! ---
**Author:** ![geepee](https://avatars.discourse-cdn.com/v4/letter/g/ebca7d/32.png) [@geepee](https://boards.straightdope.com/u/geepee)\ **Post date:** [August 23, 2001, 4:33pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/12 "2001-08-23T16:33:08Z")
this is one hot potato me and a mate fight over regularly too much sci fi me thinks , heh they should make the douglas adams “somebody else’s problem” cloaking device instead , or some other psychological type of cloaking system , since those cameras are going up like wildfire we may need them soon ---
**Author:** ![JSexton](https://avatars.discourse-cdn.com/v4/letter/j/96bed5/32.png) [@JSexton](https://boards.straightdope.com/u/JSexton)\ **Post date:** [August 23, 2001, 4:51pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/13 "2001-08-23T16:51:41Z")
> [@](#): > > \*Originally posted by Tretiak \* > \*\*Wouldn’t that kind of suit either a) be incomplete where your eyes would be or b) not allow the wearer to see? I mean the light coming into your eyes is needed by your eyes to see. The whole eye thing is why invisivility always seemed far-fetched - more so - to me. \*\* Well, imagine such a suit with a complete helmet. The light from the fiber-optic pickups on the front of the helmet is directed not only to the back of the head for invisibility purposes, but also (boosted as needed) to a flat fiber optic array monitor mounted on the inside of the front of the helmet. Thus, you could see normally. ---
**Author:** ![geepee](https://avatars.discourse-cdn.com/v4/letter/g/ebca7d/32.png) [@geepee](https://boards.straightdope.com/u/geepee)\ **Post date:** [August 23, 2001, 4:54pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/14 "2001-08-23T16:54:18Z")
heh yeah and you forget your wearing it and get hit by a car wounded badly and all , you can’t speak or move your in great pain but nobody can see you at all and more cars just think your a pothole / speed bump when they go over you ---
**Author:** ![peewee\_RotA](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@peewee\_RotA](https://boards.straightdope.com/u/peewee_RotA)\ **Post date:** [August 23, 2001, 4:55pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/15 "2001-08-23T16:55:03Z")
I guess this apllies… In one episode of “The Superfriends” Lex Luthor made these tiny crystals that stopped light from being reflected… This only worked while the ship was flying because it created a sort of black hole of white whereever the ship was… and you could see an opaque shape of the ship in the grass and stuff But don’t magicians use mirrors to do such things? What about heat that bends light waves like someone said before aobut the suit looking like things you look in the desert? I don’t really beliv in this science crap… Here is one thing you should put some thought into in achieving invisability Matthew 17:20 He replied “Because you have so little faith. I tell you the truth, if you have the faith as small as a mustard seed, you can say to this mountain ‘Move from here to there’ and it will move. Nothing will be impossible for you” But don’t worry about the scientific impossibilities… let me tell you a few more to carbon date me I would be 16 years old give or take 1 million years… If ther are 2 types of blackholes and one type is more common than the other… why have we never seen one? If nothing can get close enough the sun to take readings… how do we know the inner temperature as well as the outer? If we’ve never proven that a supernova happens (that is twinkling in stars taht can only be guessed as such) how can we get a damage report when the sun has one? Let me introduce you to a word called psuedoscience… which is any sscience that cannot be put to the scientific methode…now for the sciences that are pseudoscience… Archiology, history, biology (observing animal habits in nature), Anthropology, astrology, meteorology, cosmotology (lol), astronomy, physics (again things happening in nature), Chemestry (happening in nature) We do not even know the correct definition for gravity (fro some reason our satalite was pushed away rather than pulled in) In a tank of knowledge science has made it’s way to about 2 teaspoons of unleaded… no to mention it’s only aobut 15 miles to the gallon Never give up and never get discouraged… scince can only tell you a theory! Did you know we’ve gon colder than absolute zero? ---
**Author:** ![BrotherScrim](https://avatars.discourse-cdn.com/v4/letter/b/ed655f/32.png) [@BrotherScrim](https://boards.straightdope.com/u/BrotherScrim)\ **Post date:** [August 23, 2001, 5:04pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/16 "2001-08-23T17:04:06Z")
I’m not a genius, but I am relatively certain that absolute zero, by definition, is in fact the _coldest_ temperature, wacko scientists or no, and that anyone claiming they have achieved a colder temp is wrong at best, a wing-nut at worst. ---
**Author:** ![dalovindj](https://avatars.discourse-cdn.com/v4/letter/d/65b543/32.png) [@dalovindj](https://boards.straightdope.com/u/dalovindj)\ **Post date:** [August 23, 2001, 5:08pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/17 "2001-08-23T17:08:07Z")
There are already planes that use this technology to become invisible. They take the light coming from above them (blue sky, grey sky) and turn the bottom the same color making them invisible from the ground. Same could be done for the top as I understand it. Read about this in PopSci years ago. So I would just about guarantee they have an invisible plane. A suit is a small step away. If they don’t have one already. All you need is a good enough processor, tiny cameras, and light emmiters. DaLovin Dj ---
**Author:** ![KidCharlemagne](https://avatars.discourse-cdn.com/v4/letter/k/ed8c4c/32.png) [@KidCharlemagne](https://boards.straightdope.com/u/KidCharlemagne)\ **Post date:** [August 23, 2001, 5:14pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/18 "2001-08-23T17:14:38Z")
Of course it’s possible and not only in theory. I become invisible whenever there is housework to be done. ---
**Author:** ![KidCharlemagne](https://avatars.discourse-cdn.com/v4/letter/k/ed8c4c/32.png) [@KidCharlemagne](https://boards.straightdope.com/u/KidCharlemagne)\ **Post date:** [August 23, 2001, 5:16pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/19 "2001-08-23T17:16:19Z")
And your dang right absolute zero is the lowest temp can go, if for no other reason that time stops. ---
**Author:** ![psychomonkey](https://avatars.discourse-cdn.com/v4/letter/p/dec6dc/32.png) [@psychomonkey](https://boards.straightdope.com/u/psychomonkey)\ **Post date:** [August 23, 2001, 5:24pm UTC](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712/20 "2001-08-23T17:24:58Z")
> [@](#): > > \*Originally posted by dalovindj \* > \*\*There are already planes that use this technology to become invisible. They take the light coming from above them (blue sky, grey sky) and turn the bottom the same color making them invisible from the ground. > DaLovin Dj \*\* This is possible with just paint. Only problem is, “real men” won’t fly pastel blue planes 😉 -PSM [Next page](https://boards.straightdope.com/t/is-invisibilty-a-physical-impossibility/77712.md?page=2)