Would you go blind if you became invisible?

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Soralin
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Re: Would you go blind if you became invisible?

Postby Soralin » Sun Jul 10, 2011 3:29 am UTC

Sockmonkey wrote:Do you think surgery to give humans cat-like eyes would ever be possible? 'Cause I really want cats eye vision.
IIRC they did this is that movie with Vin Deisel. It was handled realistically in that he had to wear sunglasses in normal daylight since humans don't have cat pupils that can squeeze down to a tiny slit. It's probably doable with micosurgery but you would have to be way precise in injecting the reflective substance.[/quote]
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If whatever you're hiding from has IR goggles, no invisibility will work since a living body radiates heat and those pesky laws of themodynamics are real sticklers.
Granted you could wear a tank of liquid nitrogen on your back to cool the outside of your insulated invisibility suit but that's heavy and won't last long. Also, you could still be picked up on sonar.

Hmm, I want me some sonar goggles. Do they make them?

You could pump the heat from the outside surface into something in a different compartment of the suit and get it really really hot, and then shield it from emitting IR and visible light, and have it radiate all the heat away as UV. :) Although that doesn't help you much since then anyone with UV goggles could see you. Sonar, you could use the same sort of tricks with metamaterials to bend sound waves around you that you do with light. I remember seeing something where there were ideas to use that to acoustically hide pillars in concert halls and such, or use it to redirect waves around structures in the ocean.

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Re: Would you go blind if you became invisible?

Postby letterX » Sun Jul 10, 2011 5:02 am UTC

Soralin wrote:You could pump the heat from the outside surface into something in a different compartment of the suit and get it really really hot, and then shield it from emitting IR and visible light, and have it radiate all the heat away as UV. :)

http://en.wikipedia.org/wiki/Black_body_radiation: So, while its true that the frequency which has the peak intensity for black body radiation goes up with temperature, the intensity at every fixed wavelength also goes up monotonically with temperature. So if something is bright enough to radiate in UV, it's also still radiating plenty of IR (and visible light, for that matter). Even more than an object which is merely red-hot.

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Re: Would you go blind if you became invisible?

Postby Soralin » Sun Jul 10, 2011 6:43 am UTC

letterX wrote:
Soralin wrote:You could pump the heat from the outside surface into something in a different compartment of the suit and get it really really hot, and then shield it from emitting IR and visible light, and have it radiate all the heat away as UV. :)

http://en.wikipedia.org/wiki/Black_body_radiation: So, while its true that the frequency which has the peak intensity for black body radiation goes up with temperature, the intensity at every fixed wavelength also goes up monotonically with temperature. So if something is bright enough to radiate in UV, it's also still radiating plenty of IR (and visible light, for that matter). Even more than an object which is merely red-hot.

Well that's why you shield it from emitting IR or visible light. Use something that's opaque or reflective to those, and transparent to UV, so only the UV gets out, and run a heat pump (with an absurd temperature difference) from that outside surface back to the hot stuff to keep the outside the same temperature as it's surroundings, with the excess heat getting radiated away as UV. :)

Although that is really absurd, since getting something that can detect UV would be so much easier than this setup would be.

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Re: Would you go blind if you became invisible?

Postby Sockmonkey » Sun Jul 10, 2011 3:26 pm UTC

You can't totally shield or contain IR, you can only slow it down for a while. Thermodynamics, we are its' bitch.

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Re: Would you go blind if you became invisible?

Postby Soralin » Sun Jul 10, 2011 7:15 pm UTC

Sockmonkey wrote:You can't totally shield or contain IR, you can only slow it down for a while. Thermodynamics, we are its' bitch.

Well for camouflage, you don't need to contain it entirely, you just want the amount of IR that you emit to be about the same as your surroundings. (i.e. that the outside temperature of your suit is the same as your surroundings, and you're not emitting IR other than from that outside temperature). Now, since you're generating heat inside the suit (especially if you're powering a big heat pump), you need to get rid of that excess energy, but that doesn't necessarily have to happen in the form of IR. :)

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Re: Would you go blind if you became invisible?

Postby Sockmonkey » Mon Jul 11, 2011 5:00 am UTC

Not really. The amount of IR you can convert into other energy is pretty limited.

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Re: Would you go blind if you became invisible?

Postby Soralin » Mon Jul 11, 2011 5:39 am UTC

So you're saying that taking a heat pump that can efficiently move large quantities of heat up a 10000 degree difference, including that of the power supply needed to power it, and fitting it into a suit, just to get the other person to use a different brand of goggles, isn't feasible? :)

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Re: Would you go blind if you became invisible?

Postby Xanthir » Tue Jul 12, 2011 1:34 am UTC

Sockmonkey wrote:
Xanthir wrote:If you were transparent to *all* electromagnetic radiation, then yeah, you wouldn't be able to absorb radiant heat from the environment. You could still pick up heat from objects and the air via conduction.

You definitely wouldn't "almost immediately freeze solid", though. You'd lose heat slower than you would in a vacuum (again, because conduction is still warming you at least somewhat), and vacuum takes some time to freeze you. Meat holds quite a bit of heat, after all; plus, until you die of hypothermia, your body is still producing heat.

In Earth's atmosphere at ground level heat conducts into you way faster than it can radiate away. You wouldn't feel anything odd.

Unless I'm missing something subtle, this is clearly wrong. I'm warm-blooded, which means I am constantly producing heat in an effort to thermo-regulate. Humans can even survive when the outside temperature is greater than their preferred body temperature, by utilizing various means to still allow them to radiate heat away faster than it comes in.
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Re: Would you go blind if you became invisible?

Postby thoughtfully » Tue Jul 12, 2011 2:44 am UTC

I assume he was saying that conduction is a much bigger effect than radiation. But they both work into and out of the body, and unless its really damn scorching hot, conduction acts to cool the body, not warm it.
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Re: Would you go blind if you became invisible?

Postby Sockmonkey » Tue Jul 12, 2011 5:22 am UTC

Cooling yourself by sweating and/or fanning yourself is convection/conduction, not radiating.

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Re: Would you go blind if you became invisible?

Postby Xanthir » Tue Jul 12, 2011 5:34 am UTC

Which also still works when you're invisible, of course.
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Re: Would you go blind if you became invisible?

Postby King Author » Tue Jul 12, 2011 9:30 am UTC

EricH wrote:
gmalivuk wrote:No, it's not technological camo, it's magical camo. And if we're not allowing magic *or* technology, then the question is pointless to begin with, because invisibility is impossible.
I thought the OP was asking "what if the widget made you transparent, vs. bending light around you?" And I freely admit, maybe I didn't understand the question--but if I'm paraphrasing it correctly, it appears that capturing the incoming light pattern and retransmitting a copy from your other side is the kind of mechanism we were asked to exclude, regardless of the handwaving basis for it.
Unless the 'magic' part is that somehow you generate knowledge of the state of the universe without measuring anything.

You're right, I was specifically asking "what if the widget made you transparent."

Although I'm pretty sure you'd still have the same problem even if you bent all the light around you. Let's say you somehow created a "bubble" around yourself that bends all incoming light around the other side, so as to make you invisible to the outside observer. Well, since no light is coming into you, you yourself would experience the bubble as an area of absolute darkness. All the light is bending around you; none is coming in for you to see.

Suckily, it seems that physics works in such a way that to become truly invisible, you'd have to give up your sense of sight.

Jakkel wrote:Not quite; the Mantis Shrimp sees a slightly larger slice of the EM spectrum then we do, certainly not the entire spectrum. Their eyes only extend a little ways into the near IR and UV.

Ah, my mistake. Hmm, if a creature were seeing the entire spectrum, would they effectively not be able to see, because there'd be so much "noise" in the form of various types of radiation and so forth?

Sockmonkey wrote:IIRC they did this is that movie with Vin Deisel. It was handled realistically in that he had to wear sunglasses in normal daylight since humans don't have cat pupils that can squeeze down to a tiny slit. It's probably doable with micosurgery but you would have to be way precise in injecting the reflective substance.

Cool. Maybe I could get one cat-eye, and leave the other normal, and rather than wearing sunglasses all the time, just keep an eyepatch over the cat eye, like a pirate.
I have signitures disabled. If you do, too...you can't read this, so nevermind >_>

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Re: Would you go blind if you became invisible?

Postby Soralin » Tue Jul 12, 2011 11:02 am UTC

King Author wrote:Cool. Maybe I could get one cat-eye, and leave the other normal, and rather than wearing sunglasses all the time, just keep an eyepatch over the cat eye, like a pirate.

You could just do that already without the cat-eye, to a limited extent. Keeping one eye covered with the patch will keep it adapted to the dark. So when you go into a dark area, you can switch it over, and you have instant night vision. :)

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Re: Would you go blind if you became invisible?

Postby Sockmonkey » Tue Jul 12, 2011 12:19 pm UTC

Soralin wrote:So you're saying that taking a heat pump that can efficiently move large quantities of heat up a 10000 degree difference, including that of the power supply needed to power it, and fitting it into a suit, just to get the other person to use a different brand of goggles, isn't feasible? :)
Cheeky monkey. :lol:
Xanthir wrote:Which also still works when you're invisible, of course.
Which would also make you visible to IR as you dump heat into the environment.
Soralin wrote:
King Author wrote:Cool. Maybe I could get one cat-eye, and leave the other normal, and rather than wearing sunglasses all the time, just keep an eyepatch over the cat eye, like a pirate.

You could just do that already without the cat-eye, to a limited extent. Keeping one eye covered with the patch will keep it adapted to the dark. So when you go into a dark area, you can switch it over, and you have instant night vision. :)
And a Mythbusters fan as well I see. :mrgreen:

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Re: Would you go blind if you became invisible?

Postby Xanthir » Wed Jul 13, 2011 4:53 am UTC

King Author wrote:
Jakkel wrote:Not quite; the Mantis Shrimp sees a slightly larger slice of the EM spectrum then we do, certainly not the entire spectrum. Their eyes only extend a little ways into the near IR and UV.

Ah, my mistake. Hmm, if a creature were seeing the entire spectrum, would they effectively not be able to see, because there'd be so much "noise" in the form of various types of radiation and so forth?

No, that's just an information processing problem.

A much harder problem is the fact that you need a radio antenna to see in radio waves (which are very long) and something hardened against hard radiation to see in gamma waves (which are very energetic). You can't do this all with one organ.
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Re: Would you go blind if you became invisible?

Postby gmalivuk » Wed Jul 13, 2011 6:19 am UTC

Xanthir wrote:
King Author wrote:
Jakkel wrote:Not quite; the Mantis Shrimp sees a slightly larger slice of the EM spectrum then we do, certainly not the entire spectrum. Their eyes only extend a little ways into the near IR and UV.

Ah, my mistake. Hmm, if a creature were seeing the entire spectrum, would they effectively not be able to see, because there'd be so much "noise" in the form of various types of radiation and so forth?
No, that's just an information processing problem.
After all, do you have trouble seeing a blue ball in the grass, just because there are so many shades of green around to contend with?
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Re: Would you go blind if you became invisible?

Postby jarvisknocker » Mon Aug 01, 2011 6:39 am UTC

I think cracked.com features a host of pseudo-intellectuals who produce poor literature and writing for a mass of people who largely are also pseudo-intellectuals themselves.

There is a reason their site isn't more popular.

As for the debate, yes if it literally renders everything invisible. No if its just an optical illusion.

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Re: Would you go blind if you became invisible?

Postby KrO2 » Tue Aug 02, 2011 12:41 am UTC

It's probably worth mentioning that in The Hobbit Bilbo still casts a very faint shadow if the sun is very bright. So the Ring's variety of invisibility does still block some of the light.

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Re: Would you go blind if you became invisible?

Postby ShuRugal » Wed Aug 03, 2011 2:27 am UTC

Dopefish wrote:I wonder if you could spin up an explanation of invisibility in which it's not a matter of light passing through you, but rather the magic influencing other peoples eyes/brains to stop them from perceiving you. That way there's no personal blindness issues since you're still reflecting/absorbing light as normal, plus it means that the invisible person can still see themselves which seems to be the case in a number of invisibility depictions.



This effect is generated by a Somebody Else's Problem (SEP) field.

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Re: Would you go blind if you became invisible?

Postby Aikanaro » Sun Aug 14, 2011 3:50 am UTC

ShuRugal wrote:
Dopefish wrote:I wonder if you could spin up an explanation of invisibility in which it's not a matter of light passing through you, but rather the magic influencing other peoples eyes/brains to stop them from perceiving you. That way there's no personal blindness issues since you're still reflecting/absorbing light as normal, plus it means that the invisible person can still see themselves which seems to be the case in a number of invisibility depictions.



This effect is generated by a Somebody Else's Problem (SEP) field.

This kind of thing has been done a number of times. A main example I recall (Jedi mind tricks notwithstanding) was the Doctor, using a perception filter.

Another solution to invisibility-blindness that some folks have touched on, but not landed right on: Theoretically, you could pair a device that let, say, 90% or so of light pass through you (more/less as necessary based on magiteck available to you), with goggles that amplify the light recieved. Thus you're ALMOST totally invisible to the naked eye, yet still able to function well. And of course, you could instead go down the road (as someone else mentioned) of Predators, and could then have 100% of what the human race so arrogantly calls the "visible" spectrum pass right through you, then instead use some sort of goggles to view just outside of that spectrum.

Also, to the person who brought up the notion of the subject rapidly cooling down due to lack of absorbed radiation: Bad science, but you get 50 bonus awesome points if you got that idea from the 2000 TV series of The Invisible Man :D
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Re: Would you go blind if you became invisible?

Postby thc » Mon Aug 15, 2011 10:46 pm UTC


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Re: Would you go blind if you became invisible?

Postby Glass Fractal » Tue Aug 16, 2011 7:02 am UTC

Jakell wrote:Now, if your invisibility cloak were able to replicate a small fraction of the the incoming photons, remaking those photons with directionality and all maintained on the opposite side, then you might be able to see some incoming light, as long as your cloak was able to make up for whatever you absorbed, kind of like what James Bond's vehicle was trying to do in Die Another Day. Lots of magic, there, since I can not imagine how the car could take into account every possible viewer's perspective.


Orion's Arm explains the issue of directionality by using really complicated phased arrays to create an image in the eye of the view.

http://www.orionsarm.com/eg-article/49d2d77d2227b

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Re: Would you go blind if you became invisible?

Postby underthewronghat » Tue Jul 04, 2017 11:37 pm UTC

There seems to be a lack of creative thought on the subject of invisibility. There are many ways to achieve invisibility without being "transparent," and without being blinded. Some of these problems have already been solved: stealth technology exists for radar, but radar onboard stealth aircraft still works. Here's a short list of ideas which are probably possible, but may involve some unwieldy technology.

[*]You can capture the light after it reaches you.
[*]You can move the light after it reaches you. You could be seen, but only if someone was looking at the right angle(s).
[*]You shape the light after it reaches you, making you appear imperceptibly small, narrow, etc...
[*]You could filter the light after it reaches you, and then just wear clothing of colors which are filtered out.
[*]You can shift the wavelength of light after it reaches you --to something outside the visible spectrum, IR, UV, whatever.
[*]You could just slow down the light after it reaches you.
[*]You could speed up the light after it --er, nevermind...

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Re: Would you go blind if you became invisible?

Postby Eebster the Great » Wed Jul 05, 2017 2:43 pm UTC

underthewronghat wrote:There seems to be a lack of creative thought on the subject of invisibility. There are many ways to achieve invisibility without being "transparent," and without being blinded. Some of these problems have already been solved: stealth technology exists for radar, but radar onboard stealth aircraft still works. Here's a short list of ideas which are probably possible, but may involve some unwieldy technology.

[*]You can capture the light after it reaches you.

Then you would appear black, not invisible.

[*]You can move the light after it reaches you. You could be seen, but only if someone was looking at the right angle(s).

Then you would appear black, not invisible.

[*]You shape the light after it reaches you, making you appear imperceptibly small, narrow, etc...

Then you would appear black, not invisible.

[*]You could filter the light after it reaches you, and then just wear clothing of colors which are filtered out.

Then you would appear black, not invisible.

[*]You can shift the wavelength of light after it reaches you --to something outside the visible spectrum, IR, UV, whatever.

Then you would appear black, not invisible.

[*]You could just slow down the light after it reaches you.
[*]You could speed up the light after it --er, nevermind...

The color our eyes perceive depends on the frequency of light, not its wavelength or speed. That's why refracting light does not change its color.

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Re: Would you go blind if you became invisible?

Postby peregrine_crow » Thu Jul 06, 2017 9:51 am UTC

Another solution to the whole problem is to just have the magical gizmo that makes you invisible also telepathically send you an image of what you would see if your eyes were not invisible (or alternatively, it granting you the ability to see without eyes).

That requires handwaving away the problem of where the gizmo get's the information in this image, but I think that is a fair handwave as long as we are stuck using magic to explain things anyway.
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Re: Would you go blind if you became invisible?

Postby speising » Thu Jul 06, 2017 10:25 am UTC



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