Invisibility???

I've been wondering for a while ever since I learned about light. If you can disable an object's ability to absorb and reflect light so that the only thing it could do it transmit light, doesn't it basically turn invisible?

 

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How do you suppose the Sun rates for relative values of absorption, reflection and transmission (emission) of light?

 

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?_? what do you mean by that? I'm still pretty young and not that smart, either that or its you who's really smart. I was kinda just wondering if you disable an objects ability to absorb and reflect light, would it turn invisible? It probably wouldn't be helpful on humans because then we wouldn't be able to see. I mean, glass is a perfect example. It basically lets through all light shines on it. Would something turn invisible? How do you think we could do something like this today?

 

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Ah, when you said transmit I thought you meant as in, for example, radio transmission = emission.
My error, apologies.
Glass is a good example, but you'd have to reduce refraction as well.

 

I see what you mean. It wouldn't do a lot of good if we had rainbows appearing everywhere we went.

 

Gaah: (slaps self on head - it was late for me when I posted).
Doesn't air fit into your category?
And water (especially if you yourself are under water).

 

NewScientist reported a few months ago that such technology is a reality. I can't remember the exact issue or article, but I will try and find it for you.

(Oh, and it is impossible for us to "disable" an object's reflective properties, as it is entwined with atomic level processes. It is easier to work around the problem when dealing with invisibility, guiding light rays on a preferred path or manipulating ocular illusions.)

Article: http://www.newscientist.com/article/dn12722 (I was wrong, sort of... This invisibility cloak only works on two dimensions at the moment.)

 

The only way it would ever work is by bending light around you. But if I'm not mistaken that requires a whole lot of mass..
Another (less perfect) way would be to wear a chameleon-suit.
Shouldn't this be in pseudoscience ?

 

In answer to all your points... Read the article. Provides some great insight on how to achieve this.

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The air Force has already made a few of these invisible aircraft except they can't seem to find out where they put them.

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No.

 

Yeah, this is sort of what I was talking about. I read the article and they explained that it would be like looking at glass. The only problem with this is that it only works 2d and on a microscopic level. I think this suit interferes the light waves (which to us looks like visible light) with microwaves. Maybe in the future this could work on bigger and 3d objects. This answers my question thanks.

 

Not ?
How do you remove a materials property to absorb light as well as its property to reflect light ?
And more to the point, how to do that with humans ?
Sounds like pseudoscience to me..

 

No, I'd agree not pseudoscience: the OP was asking a question about light and its interaction with objects - not making a proposal.

 

I disagree.

He is asking about what would happen if you disabled an object's ability to absorb and reflect light.
So the question is really about modifying an objects properties regarding light.
And it's obvious why he is asking about that from the OP, or else from the title.
In effect he's asking about how to make an object invisible, and proposing a method to achieve it..

 

I read it differently: i.e. if it were possible (is this how things would be), not would it be possible...
Meh.
Maybe I'm feeling tolerant today

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Hmm Oh well..

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Hm, no because it wouldn't be transparent. It would appear as this distorted anomaly that is sucking in the light around it, somewhat like a black hole.

 

Hm, no.
It wouldn't be anything like a black hole actually.
Read the OP.

 

Light is an electromagnetic wave. The electric field of which exerts a force on both the electrons and protons in matter, but the acceleration this force produces is at least ~2000 times greater in the electrons due to their mass being that much smaller. Also except for hydrogen the protons are tied together by strong nuclear forces so the acceleration positive charges is roughly speaking some integer times 2000 times less than the "free" electrons. Except in plasma (and a few other cases like thermionic emission) the electron is not free, but bound.

The classical model of a bound harmonic oscillator electron works rather well. I.e. one can consider that the passing photon of light accelerates the bound electron at the frequency of the photon's E field passing by the electron. Now any charge, which is accelerated in a harmonic oscillation, radiates EM waves at the same frequency as the driving E field.

Here one can drop the photon concept and consider the light as a plane wave advancing in space. This means that all the various electrons of the dense matter that are on the wave front are all oscillating "in phase." Although they individually reradiate in a 360 degree plane their individual radiation only constructive interfere in the forward and backwards directions.

At this point one needs to do some math, which I will skip, except note that there is a lag in the phase of the electron's radiation with respect to that of the driving E field wave of the light. So the total field that advances into the matter is the sum of two E fields with same frequencies or appears to have its E max peak move more slowly forward. This is where the index of refraction comes from. Also inside the material (assuming there is no absorption) the various layers of the wave advancing cancel out in the backwards direction, but not near the surface does the in phase radiation by the accelerated electrons cancel out. That is where reflection comes from. (And why it has a "step phase shift" which can be demonstrated in certain "contacting" interferometer patterns, but that is getting esoteric and off subject.)

Both the slowing of the wave advance and the surface reflection (in vacuum) depend upon how strongly the electrons of the matter are accelerated. That is why both the reflection strength and speed of propagation thru the transparent material depend on the index of refraction.

Now from the above discussion, it is clear that no matter containing electrons can have zero reflection or exactly unity index of refraction. That is why no normal matter can be invisible as the OP has asked.

However, the OP's question does prompt me to wonder if a neutron star has a shadow, or is "perfectly transparent"? I hesitate to say "No shadow etc." but my simple minded understanding of light's interaction with matter spoken of above would suggest that light just passes thru a neutron star and thus it is invisible, at least for visible light. (I have my doubts* even about this conclusion and especially when one speaks of very energetic EM waves like gamma rays.)
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*Pulsars are spinning neutron stars and they have very strong magnetic fields. (I do not understand why.) Thus I sort of suspect that there is an interaction of even visible light via the EM wave's magnetic field with the magnetic field of the neutron star. This question is way too complex for me, but interesting. I.e. what are the optical properties of a neutron star in various parts of the EM wave spectrum / frequencies?

BTW Tamkinrules thanks for your interesting / stimulating question and welcome to sciforums.