Invisibilty Cloaks

[corinthum <kkearney@students.miami.edu>]

No: HPFGUIDX 48962

Sajid wrote:

> I've also wondered which creatures it works on. 
> Fantastic Beasts says that the thread that they have weaved comes 
> from an animal that can turn it self invisible. If this is true it 
> must work with animals. Also, can muggles use it? I doubt it. It 
> seems to me that the MoM would probably put a charm on it to make 
>it 
> so that Muggles can't use it. 
>   In SS/PS it hints that the cloack may not work on animals such as 
> cats. I think that it should because the thread comes from an 
animal 
> that lives out in the wilderness. It wouldnt be a very useful 
> adaptation if only humans who rarely go to their habitat were the 
> ones who could not see them
> Any thoughts?

Me:

I think we need to distinguish between invisibility cloaks and the 
animals they are made from.  The animals (sorry, no books at my 
disposal right now) are magical beings in and of themselves, and so 
I'd assume that they can become invisible to any creatures that sees 
(or rather, doesn't see) them.  No proof, just my opinion.

Invisibility cloaks, on the other hand, are made by wizards for 
wizards.  My theory is that the cloaks somehow alter the light 
passing through the cloak.  It would seem logical that the cloaks 
bend light around the person wearing them, but if that were the case, 
the wearer would not see anything (no light could penetrate the 
cloak).  So it must be altered in some other way.  Basically, what is 
needed is for the light to be altered between the two folds of the 
invisibility cloak, so that it doesn't reflect or refract as it 
otherwise would have when hitting a person, and then to proceed 
unchanged on the other side.  This would occur no matter which 
direction the light is traveling.  What happens to the light 
while "inside" the cloak?  Oh, I don't know.  But...

The alteration is made for humans.  I don't mean it only affects 
humans; I mean it is customized to be effective on humans.  But other 
animals do not have the same visual systems as humans.  Take cats, 
for example.  Cats have trichromatic color vision, like humans, but 
do not see color as intensely as humans.  They also have a membrane 
at the back of each eye, known as the tapetum, which refelcts light.  
This allows them to see almost 100 times the amount of light as 
humans.  Because of these differences in visual systems, the 
inivisbily cloak may not work as effectively on animals.  They may be 
able to see light where humans cannot.  I get the feeling Mrs. Norris 
does not clearly see Harry, but notices *something*.

Based on this theory, it doesn't matter who (or what) wears the 
cloak.  But certain animals (and Anamagi?) may be able to see or 
sense a person wearing one.  It would also make sense that there are 
magical devices (like Moody's eye) capable of reversing the effect. 

-Corinth