I call these faucets our Mickey Mouse Jazz Hands, for obvious reasons.

Various insecurities: as a math person, shouldn't this have been long obvious? as a teacher person, have I explained myself clearly? Whatever.

As teacher-person, shouldn't I be grading?

As a hungry-person, should I fix myself something to eat? I'd most like some coffee but that really seems like I'm condemning myself to being up for the day.

OTOH I've been up for two hours and I'm already sitting at the kitchen table, with my grading out as if I were about to be productive. Might as well make coffee, no?

There go the kids. I guess it's more morning than middle of the night.

Is there something wrong with your neck?

It's not long and graceful, but I wouldn't say there's something wrong with it.

Mirrors invert near and far. The reversal is percieved because we imagine moving an object through the plane into the reflected position.

The reverse-Dove deodorant probably smells wonderful.

8: It's like you didn't even wade through my long-winded post before condensing it pithily into 144 characters or less.

You should be able to move your neck in both directions.

'Up' is the direction away from the ground, and it should be the same for you and the woman in the mirror. Left is up cross front and it should be different for you and the person in the mirror, since you have different fronts.

If you insist on meaning the same thing by 'left' all the way through your thought (my left) then the mirror doesn't reverse left and right, since her right hand is on your left. Likewise, text that goes from left to right here goes from right to left in the looking glass world, because it goes from our left to our right.

Yes, but biologically one of those neck movements is way more common than the other. So in the absence of actual knowledge, you presume left/right motion.

I didn't actually make sense of 11.2 and so I ignored it.

Or 11.3.

'Up' is the direction away from the ground, and it should be the same for you and the woman in the mirror. Left is up cross front and it should be different for you and the person in the mirror, since you have different fronts.

If the sun is shining from overhead, both our heads are warm. If the sun is setting from the west, both of our west sides are warm. "Left" is only meaningfully different from "up" because we're used to reading left/right.

In 11.2, I meant that left is the cross product of up and front. Since you and the woman in the mirror have different fronts, you have different lefts.

Right, to have any true meaning of orientation, you have to make some convention involving all three axes. Once you're involving all three axes, it's not going to distinguish left-right from up-down without involving biology.

Chirality is physics, but chirality doesn't explain why we preference one axis over the other.

Comparing reflection to rotation is always going to result in one axis being flipped, but which axis depends on which rotation you're doing. If you're looking at yourself, standing up, it's most natural to imagine rotating yourself in a way that maintains your symmetry, so about a vertical axis, not a horizontal one. But if you're looking at something else, or at a funny angle, you can convince your brain that the "natural" identification is rotating about a different axis.

If it makes you feel better, I only sat down to think that out last week. What makes you a math person is eventually thinking about it, not how long it took before you did.

This post is seeming like a worse and worse idea, the later into true morning it becomes.

20: The thing is, I have thought about it, and I thought I truly understood it, as an artifact of biology. (I even posted about it years ago and it turned into a tedious argument.)

I just got a bit confused when I noticed the faucets and had to re-derive everything again for myself. (I probably didn't need to post it, though.)

Maybe I should post something new.

Up-down is fixed first and is the same for everyone in your country, then you fix front depending on which way you're facing, then left and right.

If you insist on fixing left first (e.g.: by left I mean west), then the mirror won't reverse left and right.

You have to tell a funny story to pick different objective directions for up for you and your mirror image.

If (for reasons of biology, language, physics or whatever) up were generally different for people facing each other (everyone has to do a head stand when facing east or north, we're on a funny kind of space ship, we just all think of up as east X front), then mirrors would reverse up and down. In the first two cases, we would ask why the woman in the mirror's head is pointed in that direction. In the last case, the mirror reverses up and down because it reverses fronts.

Here's Richard Feynman having a go at it.

I like Heebie's crack of dawn posts. They're the only thing going down on the American internet this early in my afternoon.

22: Wasn't this exactly where the discussion on this came out the last time?

RTFA.

26: That I had confused myself and just needed to re-derive things for myself?

More accurately, I thought it had been a hung jury, with people fervently advocating both sides of ALL PHYSICS and ALL BIOLOGY. I myself have always felt it was biological, and then was kind of thrown this morning by the faucets.

I even posted about it years ago and it turned into a tedious argument.

Yep. Cue tedious neb in ... a couple of hours.

Beamish link goobered up a bit. Here are the comments.

That thread did cause me to do several experiments with writing in different orientations. The continuation of Feynmann discussing the train wheels in 25 was more interesting and new to me when I heard it.

30: Neb's take would probably be, "Righteously angry neb decrying the tedium of others."

Feynmann on the train heel thingie.

You could get a mirror to reverse up and down by putting it on the floor and walking on it. Then we'd say that the people in the looking glass world are upside down, since the path from foot to head for them is opposite from what it is for us.

The link in 32 is great. I had never thought about why it was even something to wonder.

You could get a mirror to reverse up and down by putting it on the floor and walking on it.

If only someone could literally post a photo of how a mirror could reverse up and down and put it in the OP.

33: And when you raised your right hand you'd still perceive at as your left hand being raised (lowered).

Actually those tub handles are well set up to do what I thought was an actually interesting experiment (to me anyway) on it. If you turned them 90° you would perceive the writing as more typical "miirror-reversed". Turn them slowly and see where that perception flips. Is the perceptual flip in the same place when you go "word axis" parallel to mirror -> perpendicular as when you go slowly from perpendicular to parallel?

Report back here.

If only someone could literally post a photo of how a mirror could reverse up and down and put it in the OP.

Well, great, that, too. When you set a mirror at right angles to the up-down direction, the down (or up) will be what's closer to the intersection of the direction and the mirror, and the mirror will reverse up and down.

In your example, the up-down direction is determined by the writing on the taps.

32 was a disappointment

I was hoping Feynmann was going to explain why spinning or rotating wheels sometimes appear to moving in the reverse direction, switching perceptually from counter-clockwise to clockwise at a high rotational speed.

This thread could also be extended by using it to riff on Lacan's "mirror-stage."

32 +w.

37: Experiment carried out.

So, the hot faucet turns clockwise and the cold faucet turns counterclockwise, right? So as you turn the water on, the "H" stays on the upper left, whereas the "C" travels to the lower left. So the H stays as the dominant starting point for much longer than the C does; "Cord" starts to look like "Dloc" at a rather shallow angle, while "HoL" keeps looking like "HoL" for a rather large angle.

why spinning or rotating wheels sometimes appear to moving in the reverse direction

Those are called spinners, bob. Your whip doesn't have spinners? Get with the times, daddy-o.

39: Covered here.

That was me.

So, the hot faucet turns clockwise and the cold faucet turns counterclockwise, right? So as you turn the water on, the "H" stays on the upper left, whereas the "C" travels to the lower left. So the H stays as the dominant starting point for much longer than the C does; "Cord" starts to look like "Dloc" at a rather shallow angle, while "HoL" keeps looking like "HoL" for a rather large angle.

Cool. C has up-down symmetry, T has left-right symmetry, and H has both.

The mirror flips the direction heading into the mirror. In ordinary cases when you're facing the mirror, that's front. In the taps case as in the original photos, that's up. If you stand on a mirror, that's down.

If you rotate 'HOT' clockwise, you change the direction perpendicular to the mirror from up to left. The 'T' will become normal, and no amount of rotation will make the H or the O look funny. The T will only look normal once you mind processes the direction heading into the mirror as left and not as up. At that point, the text will look like 'TOH', since left right will be reversed.

(I think. It's very easy to be overconfident about this stuff.)

I was thinking that I had written something very confused and wrong in the last thread on this topic, but I see I avoided that.

Say, heebie, why do people have left-right symmetry but not back-front symmetry or top-bottom symmetry?

Because of mirrors?

48: Whoa.

Just spitballing here:

They have top-bottom asymmetry because they're terrestrial creatures, and they need to interact differently with the ground and the air.

They have front-back asymmetry because they're mobile creatures. It valuable for them to be able to accelerate but not valuable for them to be able to accelerate in more than one direction.

There's no explanation for why they should have left-right asymmetry, and symmetry is the default structure.

How did I do?

How did I do?

You totally failed to be heebie.

Also you got one of the axes wrong.

I don't even see air.

Some of us have five-fold rotational symmetry.

You totally failed to be heebie.

Nobody's perfect.

Also you got one of the axes wrong.

Which?

54: If you call that symmetry.

And I'm sure your right side looks exactly like your left side.

I have one leg 1/4" shorter than the other and one big toe nail is black (from running, I hope).

Yep. Cue tedious neb in ... a couple of hours.

[Outraged sputtering]

56: looks more like zucchini to me.

I haven't really followed this thread, but I don't see how there can be a biological component when the camera produces a set of pixels, not subject to the interpretation you posit, in which the exact same effect is present.

Thanks, Heebie: I had been thinking about this problem a few nights ago so it's gratifying to see this here. I'm of the real transformation is front-to-back, you flip the text/object around vertically and not horizontally for psychological reasons and that's what really causes it, but once you've made that transformation the optics guarantee the apparent horizontal reversal school. (Certainly, it needs a better name.)

After reading through the old thread potchkeh linked to, I really want to claim ignorance of the Monty Hall problem, for the lulz.

I hate everyone.

I've no problem with any of the explanations as long as the cat is alive at the end of the experiment.

63: That's already factored into our models.

Look, the R on the paper and the R in the mirror are facing the same way! I wrote the R on the paper in the normal fashion, but then, of course, I turned it around so it would be facing the mirror, and what do you know, it was turned around.

You're younger than I thought.

67: Nosflow's mirror displays full CPT symmetry. He's well into his 60s and is composed entirely of antimatter.

The case that heebie is concerned with is different in some respects from the standard problem that Feynmann, Lw, and neb have solved. When the mirror is oriented so that up and down go perpendicularly into the mirror then the mirror will reverse up and down in a way that it can't when the up-down axis is parallel to the mirror.

When I read Feynmann on mirrors and train wheels, the other question I remember him posing was "Why are manhole covers round?".

Because manholes are round.

Incorrect!

Even if manholes were square, manhole covers would be round?

Because people need to be fired.

73: Yes.

Square manhole covers

The reason manholes and their covers are usually round is, as maybe everyone knows, because if they're both round and the cover has a bigger diameter than the hole, it won't be able to fall down the hole.

Because man is round.

That's just creating an incentive for utility workers to be careless about where the put the manhole cover.

I would doubt the Dove makes much difference underneath all of that Tresor.

Anyone else trying to read what looks to be a bill from nosflow's insurance?

And beamish is, of course, correct. Also, because you can roll them.

Spherical manhole covers would be even easier to roll and just as safe from falling down the hole.

no

55: front-back asymmetry is because of pooping.

84: False. It's because of eating, which necessarily predates pooping.

What about meconium?

Eating also predates mammals.

I thought we were talking ontogeny not phylogeny.

84: no, front-back asymmetry is because the gods were afraid.

Logically, since ontongeny recapitulates phylogeny, we eat before we poop.

55: front-back asymmetry is because of pooping.

I guess the test cases are immobile animals, like barnacles. Do they show front-back asymmetry in the relevant sense?

Do nearly hatched birds/lizards/etc take a shit after they hatch from the egg?

Nearly s/b newly.

The faucets above are half-rotated (towards the mirror) like a roll of toilet paper, whereas the deoderant below is half-rotated like a revolving door

Huh?

91: no, and neither do not-really-mobile animals like clams, from what I understand.

Hm, I might be wrong. Claims appear to have anuses.

Barnacles appear to poop out their mouths.

Anuses certainly make claims.

The biochemistry of left-right asymmetry in vertebrates is interesting, only partially understood. I am really curious about whether the shortened lifespan among human lefties obtains in other species where the degree of brain asymmetry varies between individuals.

Dammit! Clam anuses! Don't claim anuses! Clam anuses! Clam anus! Clam anus!

Clam anus!

A man, a plan, sun a mal clam anus al Panama!

Clamanusation.

See my arXiv paper, "Spontaneous symmetry claim-making breaks clam anus claim chains".

Sun amalgam god dogma glam anus.

Clams have anuses, but not in a way we would understand. At least I hope that is the case because they poop in their shells.

Salve, Regina, Mater misericordiæ,
vita, dulcedo, et spes nostra, salve.
ad te clamanus exsules filii Hevæ

Next time that comes up in church, I'm going to be incapable of not reading it "clam anus."

If you teach fish to drink you have a place in heaven,
But if you give a clam an anus you're an awesome fucking God.

Give a flounder a mirror.

what 61 said.

all this biology and culture stuff is unnecessary. take that picture of the faucet, crop off everything but the reflection of the word "COLD" and you can still see that it's been vertically flipped by the magic of: you're seeing the word "COLD" it as the mirror 'sees' it.

but I don't see how there can be a biological component when the camera produces a set of pixels, not subject to the interpretation you posit, in which the exact same effect is present.

I see your confusion. Let me clarify by saying I'm not concerned with the mirror's biology.

Glassist.