What’s the standard one (citation please) and doesn’t it appear obvious to you guys that the study’s authors are using my definition, not this “standard” one you guys are referring to?
If they’re saying that my mirror image as observed by me is half my size, isn’t it quite clear that they must be talking about the plane surface reflecting light from the mirror that I naturally interpret as containing all and only an image of myself?
That would yield the conclusion that my mirror image is the same size as myself, not half of my size. (I’d disagree that you’ve measured a thing this way, but that’s another thread probably.)
Since the study says the mirror image is half the size of the thing reflected (from the reflected thing’s point of view) then mustn’t we conclude that either the authors and their journal editors are insane, or else they’re talking about something else when they say “mirror image”?
Njtt, what is your reason for insisting that “mirror image” refers to a “virtual image”, and not a “real image”, as defined in the very link you posted?
Do you not think that mirrors have both virtual and real images associated with them?
As far as I can tell, this is not correct. By placing the mirror practially against your nose, such that the top of your virtual self’s head appears at the very top of the mirror, then at the very bottom of the mirror, you will see your feet. This is based on diagrams I’m drawing, though–not on actual experiment with a mirror.
This means the image–the actual image that lies on the mirror itself–is half your size.
There is no “real image” produced by a plane mirror. A real image is one that can be focused onto a screen. Real images can be formed by convex lenses and by concave mirrors (though the latter can form virtual images too). They are not formed by plane or convex mirrors.
The area of mirror surface that reflects the light from you is not the image of you, and it is certainly not what is meant by the optical jargon term “real image”. You can talk about it if you want, but it is not what people usually mean when they refer to a mirror image, either optical scientists or laypeople.
Prior to this thread, if you had been standing at a mirror, and drawn an outline with marker of your face, and then stepped back, would you have expected the outline to continue to hug your face tightly, or would you have expected your reflected face to begin appearing smaller than your outline?
How would you have described the actual result? Would you not have said something like “It turns out my mirror image stays the same size no matter how far I am from the mirror”? And if you would have said that, wouldn’t you have had to mean “the area of the mirror containing the image of my face” when you said “mirror image”?
I dare say that some light from your feet will be reflected off the mirror surface, but good luck with actually seeing the reflection of your feet under these circumstances.
Why do you think I wouldn’t see my feet under these circumstances?
Are we all agreed on the following:
If I draw an outline of my head as it appears on the mirror, and then step back several paces, my head’s image will still appear to take up exactly the space of that outline.
That outline will be half the size of my actual face.
If I draw an outline of my friend’s face as it appears to me on a mirror, then step back several paces, my friend’s face will now appear to be larger than the outline I drew.
Here’s more info. (Caution: I just skimmed it.)
I would have said something like “the area of the mirror containing the image of my face”, because “mirror image” already has a different meaning to me. When I read your link in the OP, I had to think about it a bit to realize what the author meant by “mirror image”, because it isn’t the standard optics meaning.
I agree with your points 1, 2, and 3.
ETA: I’ll also admit I hadn’t thought about how big “the area of the mirror containing the image of my face” would be before this thread, and that it wasn’t immediately obvious it would be 1/2 the true size.
Well, this ain’t something people normally talk about, is it? If it were, the effect would be well known. Yes, I suppose that if I felt the need to to make up a term for the relevant area of mirror surface on the fly, I might call it a “mirror image”. This would be an unfortunate coinage, however, because it would create ambiguity with the established lay and scientific senses of “mirror image”. If it is a structure of any great scientific interest (which I rather doubt) we ought to coin a new term for it.
You could look through a window and see someone else’s face. You could take a marker and draw around the area on the window where their face appears. Do you think the area thus demarcated (or the light from their face passing through it, or whatever) is properly or normally called the image or “window image” of that person’s face? A mirror is like a window into a world of virtual images.
Your eyes do not have a vertical 180 degree field of vision. They will not even turn far enough.
You make many assumptions about my physiology. 