Mirrors - why do they reverse sideways rather than lengthways?

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Y'know? Sorry, I'm sure there's an obvious answer to this but I can't work it out.

― Nick, Thursday, 20 September 2001 00:00 (twenty-four years ago)

They don't reverse either really. Your left side is still on the left hand side of the mirror and you right side still on the left. The problem is we determine left and right from the direction we are facing and when we look in a mirror that is the one direction that is reversed. So our reflection's left and right sides are the wrong way round with respect to the direction they are facing, but still the right way round with respect to us.

― Richard Tunnicliffe, Thursday, 20 September 2001 00:00 (twenty-four years ago)

...right side still on the right...

― Richard Tunnicliffe, Thursday, 20 September 2001 00:00 (twenty-four years ago)

Of course mirrors can be made to reverse lengthways if they're curved in the right way.

― Momus, Thursday, 20 September 2001 00:00 (twenty-four years ago)

Right... and furthermore, because human eyes are oriented horizontally on our face, which explains specifically the left-right thing, not top-bottom thing.

Hopefully I'm not discriminating against the minority of humans that have eyes on the top and bottom of their faces. If so, I apologize.

― Brian MacDonald, Thursday, 20 September 2001 00:00 (twenty-four years ago)

I can't quite see how the positioning of your eyes makes much difference.

― Richard Tunnicliffe, Thursday, 20 September 2001 00:00 (twenty-four years ago)

the mystery of mirrors = a mystery to me

anyone ever seen a "true mirror" where with all sorts of fancy tricks hidden in a shallow wooden frame they actually do reverse the image so that when you, say, wiggle your right ear it's the left one that moves in the mirror?? spooky business. something about those mirrors makes one look slightly deformed as well. probably the fact that it's accurate.

― Tracer Hand, Thursday, 20 September 2001 00:00 (twenty-four years ago)

Those sound interesting. Disconcerting, too. I'd like to see one.

― Maria, Thursday, 20 September 2001 00:00 (twenty-four years ago)

If a mirror did not "reverse" side to side it would equiv to rotation 180 degrees abt an axis vertically down the plane of the mirror at the point nearest you = Operation A

If a mirror did not "reverse" top to bottom it would equiv to rotation 180 degrees abt an axis horizontally across the plane of the mirror at the point half way up you = Operation B

Operation B wd mean your "reflection" was upside down. Yr reflection is NOT upside down hence mirrors DO "reverse" top to bottom exactly as they do side to side. It's because they DO "reverse" top to bottom that you see youself right way up. QED

― mark s, Thursday, 20 September 2001 00:00 (twenty-four years ago)

It's quite a while since I've been this confused.

― scott, Thursday, 20 September 2001 00:00 (twenty-four years ago)

I'm slightly confused myself now.

― Richard Tunnicliffe, Thursday, 20 September 2001 00:00 (twenty-four years ago)

all i know is there is one handsome right-handed bastard living in my mirror at home.

― ian, Thursday, 20 September 2001 00:00 (twenty-four years ago)

you are confused by the bright glare of true explanation which is causing the wool in yr sorry noodles to heat up and smoke somewhat

― mark s, Thursday, 20 September 2001 00:00 (twenty-four years ago)

The bright glare of obfuscation more like.

― Richard Tunnicliffe, Thursday, 20 September 2001 00:00 (twenty-four years ago)

This is going to keep me awake tonight.

― scott, Thursday, 20 September 2001 00:00 (twenty-four years ago)

Wow. Am I ever impressed.

― Kim, Thursday, 20 September 2001 00:00 (twenty-four years ago)

In double-reflections you get a "True Mirror" effect (double reflections, meaning two mirrors facing each other at 90 degree corners, like in a diner wall corner or something).

In these reflections, my mouth is horribly crooked, my head cocked to one side, face uglier than I'd like it to be. In a regular mirror I look normal (to me). Yet, I must truly be ugly because in pictures I often look like the double-reflected me. It's just odd that backwards I look straight and forewards I look crooked.

― Nude Spock, Thursday, 20 September 2001 00:00 (twenty-four years ago)

what about spoons?

― rainy, Friday, 21 September 2001 00:00 (twenty-four years ago)

Has to do with the fact they dont use mercury in mirrors anymore. Cause when you use mercury it doesnt have that problem. Like rotating mirrors, particularly the liquid mercury mirror at Universitie du Laval, it doesnt have that problem. Infact it distorts much like a parabola would, like the oppositie of a security mirror at 7-11.

― Mr Noodles, Friday, 21 September 2001 00:00 (twenty-four years ago)

Nick, this has to be the daftest question you've ever asked. Are you ill?

Obvious answer: 'cos it's a mirror, not a bloody lens.

There is something called a rorrim, where you see yourself as others would see you, but I've no idea how they're put together.

― Michael Jones, Friday, 21 September 2001 00:00 (twenty-four years ago)

Michael, I know it's stupid but it's still quite hard to answer (see above). You're thinking of it in terms of physics where the real answer surely has to be mainly psychological.

― Nick, Friday, 21 September 2001 00:00 (twenty-four years ago)

Nick: why does the answer have to be mainly psychological? Is there some kind of conundrum lurking here which I've completely missed? A flat, reflective surface presents the eye with an image of an object the same (virtual) distance into the plane of the surface as that object is from the reflective surface.

Now, if you place a mirror above your head and look up - well, your head is at the 'bottom' of the image presented to you, so there's an example of 'lengthways reversal' (except of course, it's the same thing).

― Michael Jones, Friday, 21 September 2001 00:00 (twenty-four years ago)

Mike. Lettering is the best evidence of what I mean. Now matter which way the mirror is positioned, the letters always look left-right reversed. Never up-down reversed.

― Nick, Friday, 21 September 2001 00:00 (twenty-four years ago)

They are not left/right reversed, they are back/front reversed. It's like you are looking at them from behind.

― Richard Tunnicliffe, Friday, 21 September 2001 00:00 (twenty-four years ago)

Hang on, I think this might make you understand. Take a piece of clear plastic and write something on it using a marker pen. Now, whilst standing in front of a mirror hold the plastic in front of you so you can read from left to right what it says on the sheet. Its reflection will still be readable.

― Richard Tunnicliffe, Friday, 21 September 2001 00:00 (twenty-four years ago)

Nick: what I don't understand is why you would expect, under any circumstances, an inversion and not a mirroring. Why is this a puzzle? Mirrors don't invert, they mirror.

I'm beginning to suspect this thread is some kind of test. I presume I've failed with my silly physicsy ways.

― Michael Jones, Friday, 21 September 2001 00:00 (twenty-four years ago)

I've always been far more confused and worried by why this is thought to be a big thing than why it happens. (I touch the mirror with either hand => I'm touching the outstretched hand of my reflection) => I am perfectly happy. I'd find it far more confusing if this didn't happen. So why was it still worth going, "Ooh, isn't lateral inversion a strange and bemusing thing?" even in my GCSE Physics Textbook?

I'm more interested in what my cat thinks about mirrors. I mean, when she was a kitten she was bemused by them and would look behind them for stuff, but now I'm 99% sure that she understands them as well as I do; if I blink at her in the mirror then she'll blink back and walk to where I actually am. The 1% of doubt is that she isn't in any way interested in her own reflection; no self-consciousness, no vanity. I'd have thought that knowing that it was your own reflection would elicit at least some occasional inspection of your current appearance. Maybe that's just totally a human attitude, though. I wonder if she would, for example, think to use a mirror to wash out something stuck in her fur? Hmm.

Yeah, on that flamewarriors site, I am so that person who obliviously rambles on about her cat at inappropriate moments. But then I'm several of the other flamewarriors too. They didn't have one which combines all my irritating habits and is also needlessly paranoid about everyone hating her but somehow never takes the hint when people do actually want her to shut up and go away. (If you're thinking "damn right" at this point, then email me outright and I'll leave.) Oops.

― Rebecca, Friday, 21 September 2001 00:00 (twenty-four years ago)

The point is, I am an idiot.

― Nick, Saturday, 22 September 2001 00:00 (twenty-four years ago)

The point is, surely, that you're one of the smartest people I know and your posing of this question indicates a way of thinking that baffles me. Which is kinda interesting in itself. We're not simply defined by our choice of degree subjects, are we?

― Michael Jones, Saturday, 22 September 2001 00:00 (twenty-four years ago)

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