Why do mirrors flip horizontally (but not vertically)? 

All she needed say was that mirrors show exactly what they see. Go to a mirror and try it; the mirror will show exactly what it sees.

A mirror shows a reflection, simple. She just over complicated it

A mirror copies all the light that hits it and sends it back where it came. It's not flipping anything. It's like a rubber stamp on paper, but with light.

LOL ITS JUST ONE ASSUMPTION :P HOWEVER NICE FOR DA CLEARUP. N DAT GALZ R STILL HOT AS FUG. IM JUST HONEST N YEAH A DUDE. ++ (COULDNT JUST FOCUS N WHAT SHES TALKING)

me too

Did you just...

Perfect pun doesn’t exi...

You're gonna be a great dad

You must be PUNished :)

I mirror your move

...ereht morf gnipyt dna rorrim eht ni deppart ma I woN ,raelcnu snoitcurtsnI

S

That's a horror movie plot in the making.

Say "hi" to Mirror Julie.

You've been watching too much of the flash mate 😂

I think this part makes it all make the most sense. That it’s a z-axis flip.

I'm glad that you came away enlightened. From the comments, I think most of us did not.

It is not a z-axis flip. The mirror is simply reflecting light. I can not understand why so many people have troubles undertanding that.

@@musknoer89 the mirror reflects light VIA the z-axis, which is why it is correct to call it a z-axis flip AND the mirror simply reflecting light.

@@prehensiledale1215 that doesn't make sense and is simply wrong which is why I pointed that out. Try standing slightly on an angle the left or right of a mirror and point a laser at it. If it is a flip in the z-axis, the laser should reflect towards you. Do you really think the laser will be reflected directly back at you? The angle of incidence equals the angle of reflection. Calling it a flip in an axis is nonsensical when talking about a mirror.

get yourself a De lorean

+Madscientist with a doc brown.. and a idiot sycopath

HAHAHHAH

119 llɒɔ

;) ...gniniart fo sraey sekat kcutsnu gnitteg yletanutrofnU .taht tuoba yrros ma I

this is literally the greatest comment in the history of comments

😂😂😂 Genius comment

Lmaooooo

LOOL😂

Well at least its not a particular body part stuck in a mirror.

She was a "why?" child rather than a wild child ... 😏

Yea but she's so darned cute what parent could get mad at her?

@@garymartin9777 i think she is right.

I can’t stop smiling at how brilliant she is.

absolutely.. I think to she drove her parents insane with questions. I know that's why she is so smart, ask questions to find out the answers.. She ROCK's..

+The Technoclast hats off

Damn, The opposite happened to me!

+Taran Singh I'm a multitasker 😏

+The Technoclast you've made my day :D

+The Technoclast My faith in humanity is restored....now to scroll down and read some more comments to obliterate it again.

:))

@BluesyBor I don't suppose you've watched the film "Mirrors" (2008) then. It's an effective way to develop a phobia of mirrors, I'll say that much.

Mine does it all the time... We cant really talk with each other because of this.

so creepy ~

personally, it went from wtf to "ah"/"duh" once she said it's flipped in the z-axis

Can you provide me with a link of a product in real life? I want to know the keyword so I can get one.

you can do this today with an LED or TV screen with a cam that you configure to flip he image horizontally - Voila

And then we would all be more confused than ever. If I hold a mirror above my head, I dissappear. Only my bald head is up there and, since I can't see it, I have disappeared. So there !!!

mirror mean it just reflection not flip.... got nothing to do with what direction....

Honestly, she caused some of the confusion intentionally, if she just wrote something in the mirror which was written on a transparent paper it would have made it clear

I was frustrated, then I broke the mirror, and it was an entire room mirrored in my direction and the mirror was just a glass window.

Try watching PBS spacetime for a few days. You think you understand, and then you get lost, but then find your way again and by the end of the video it leaves you with more questions than answers.

Bruhh..this is easy...my father also taught me this

cant you just lie down? that mirror is pretty heavy🥂🥂🥂

The is the "BEST" explanation and should be locked at the top of the comments. Thanks.

@Amethyst not sure what you mean by "normal line" but a convex mirror reverses in the plane of the mirror just like a flat mirror. For a concave mirror things are complicated by the fact that the light is focused and then spreads out again. The appearance of the reflected image depends on where your eye is relative to the focal point. Past the focal point the image is rotated as well as flipped. Your image will be upside down.

I have a better idea Don't worry about what the mirror does to your image just worry about the person in the mirror 🍦

Your point complements her explanation nicely. That image you see from below is also flipped in the z direction, the component perpendicular to the mirror plane, towards you. Just like the others she demonstrates.

Jesse Stewart - As Captain Jean-Luc Picard would say: Well, they say if you travel far enough, you will eventually meet yourself.

* vsauce soudtrack stars playing *

The mirror lies, and it toys with your mind.

That is when it all made sense to me!

The earth is flat.

People have to understand that there are unintelligent people in this world, there always has been and there always will be (relative to the average IQ at any given period). Just because something seems obvious to you, doesn't mean there aren't many people who struggle intellectually who would benefit from this knowledge. I don't understand how you can't get this.

bdalem Because its mirrors. They are intuitive to everyone without a serious mental disability. And besides, how does explaining it wrong benefit anyone? And to top it of, this is a pretty confusing video thats hard to follow.

w0mbatina It honestly baffles me that someone might not understand how a mirror works and after reading some comments on facebook and on here... it's truly sad some people struggle with a concept as simple as a mirror. She didn't even explain it properly.

I completely agree with you. Just raising the question of "why do mirrors flip things?" adds more confusion to the topic since, like you said, a mirror doesn't flip anything, it just reflects.

Not everyone has good geometric / spatial awareness dude. At some point it became obvious to you. Just like there are things which are complex to you and obvious to these people.

"..... damn it!" Physics Girl, probably

😟🤯

Big Brain

I think it's because the Mirror is a Translational symmetry rather than Rotational symmetry of the image

This is exactly what I was going to post. Glad your post is at the top. :)

then add to it [in our perspective]

More precisely, it laterally inverts.

THANK YOU!

exactly it reflects light where it hits it

Same thing. If you teach children, the word flip is synonymous with reflect or mirror. She is making something non-intuitive simple to the average kid or adult.

Or stand on it

Instructions unclear Mirror pieces stuck in the face

Or stand *over* it

I just had a mini mind explosion!

ooh

🤣🤣

😂😂😂 Same bro

In fact, we have spent many years visually compensating for our asymmetries as apparent in a mirror. When we see a photo (or correcting mirror, or live camera display), the asymmetries are exaggerated because they go in the opposite direction.

@@RaineStudio spot on

Oh boy… I just commented almost exactly the same experience before I saw yours

If this is the case, why nobody gots confused about selfies vs "normal photos"? If your theory is correct, other people should feel (or don't like) your selfies, because a selfie is a mirrored image, i.e., the same as when you look into the mirror. I never heard anyone saying, "oh man, in this group photo, you look nice, but the selfies you showed me, something seems odd". Do you disagree?

@@StefanHoffmann84 because after you take a selfie the device flips it horizontally so the saved image is now normal like how people view you irl.

I hadn't until someone asked me!

cuz they're not flipped. theyr'e just mirrored

I JUST asked the same question LOL!

It's because you simply kant.

kant Because it's the simplest physics.

I lol'd.

Did you check the mirror?

Don't worry we all lose thousands of brain cells every day

PLEASE BE CAREFUL.

It will flip you on.

You just made my day!

you get seven years of good luck..

But what if i flipped the mirror off ? 7 Days bad luck !

+1

👍👍

Well said ;)

yeah man i'm sure you are the 1 one to came up with that.

She probably doesn't give a damn about physics. Rather, she is just some media company's business venture. Chill yourself.

That's no plot twist, it's the foundation of a horror story.

Plot twist: thats not a joke 2:31

Physicists: enjoying complications since the 1600s

🤣😂🤣😂

Physics is theoretical but the fun is real😂😂😂😂

It's the same physics that developed tech nd made it possible to write this comment

@@spacebarbarian._ Of course!!!! *physics is more than just important*☆

Thank you for the nice comment! Glad the video cleared things up.

Physics Girl I think that was sarcasm....no wonder you do science about mirrors...

***** You are entirely wrong, *and* you suck at detecting sarcasm.

***** Because random, unknown RU-vid commenters are totally trustworthy, of course.

It's not science. Trust me, I'm a soon-to-be engineer, she just gave you 1% of the real explanation.

You're a king under all physicians. With joyful laughter, I solute you.

lol lol

😂

What if you turn the mirror inside out ?

Lol, um sorry loL

+William Barnes Actually they don't "flip" at all.. It's like the old mind game joke "What goes up and down but never moves?" to wit the answer is : A road... The mirror is stationary and its the light wave which hits and bounces back in an exact opposite direction. Therefore, the only thing which actually changes is our own individual "perception."

Chris Banzet No, they absorb photons and emit different ones with reversed chirality. They actually flip them front to back.

+William Barnes No, they do NOT recreate new photons. Its the same photons being ricocheted back at the observer. And again, they don't actually reverse, there's many scientific documents available that you can read about the subject matter. "chirality" is not the exchange of molecules produced by a mirrored reflection, they merely use the mirror image to create an impression of it being "identical". Chirality is merely the state of equal identity to another molecule - see this definition "Chirality is a property of individual molecules. If a molecule is chiral then we know that the molecule has two enantiomeric forms (which are almost identical but are actually different molecules)."

Chris Banzet I'm going to give you a moment to read those "many scientific documents available" yourself.

+William Barnes I've already spent about 35 plus years reading them, I don't NEED to read them again.. I know what the internet says, and I know what science says.. They're contrasting, and definitely there is a truth, and yours wreaks of Google searching..

+Simon Clarkstone Actually if you have a sticker in the back window of your car intended to be read from the outside, it looks right in the mirror.

Yep.

+Simon Clarkstone - Good idea - I was thinking along these lines, but didn't quite graduate to clear plastic (I was thinking thin paper with dark ink and light shining from your side.).

+Robert Billing Also, very interesting!

+Robert Billing does it also look right to our eyes?

It flips perpendicular to the plane of the mirror.

+carultch The light coming from the mirror, what I consider the reflection, doesn't flip at all. That's exactly why it looks backwards.

Jim Doe Oh, but it does. The mirror reverses the perpendicular component of the incident light's momentum, and preserves the parallel component.

+carultch All you're saying is that the mirror reflects light. Whoopdiedo. We know that already.

are you fucking dumb?

You better watch out(pun) cause they do not regenerate.

bara siddiq uh, yes. Yes, they do

@@justagirlsittinginasink4041 really??!! 🤔🤔 Well thanks for correcting me

bara siddiq you are actually constantly losing and regenerating brain cells every second!

@@justagirlsittinginasink4041 Nah you don't, you are born with a fixed amount of neurons that you take to your grave, with the small exception of small areas like the hippocampus that indeed show some form of neurogenesis, although very minor.

@Sune Wallentin Goettler i need a science fiction with these beings in it please

How so?

Because they do flip things horizontally...

they don't flip anything. They just refect light where light meets it

That's her point! Did you not listen to the video?

First, this was obviously a question presented to her, not asked by her, so obviously someone wondered this. Second, yes. If you watched the video she very much said there is no flipping horizontally so you're arguing for a point that was not made.

the physical pain watching this video 25 seconds is unbearable..

To turn a “q” into a “p” I need to flip it by rotating it out of the plane by 180 degrees. When I see my mirror image I think it is me rotated 180 degrees and looking back at myself. But it is not, since if I was looking back at myself and both my “selves” raised our right hand we would raise the contralateral hand but in a mirror when I raise my hand I see the ipsalateral hand go up. This is because a mirror is a reflection in the plane and not a rotation in 3D space. To see yourself in a mirror is not the same as seeing yourself in 3D space as others see you. I noticed this when I once looked at my cat in the mirror. She had asymmetrical markings on her face and she looked weird, yet this is the only way she would see her face. In short, flipping is not reflecting.

Where do these people come from. Maybe another flat earth 🌍 conspiracy

P. K. Flat earthers have members all around the globe. A globe is spherical. Flat earthers proved wrong.

In big print put number 813 on a piece of paper, underline number . Hold in front of you in front of mirror . With fingers on sides turn the paper over , top to bottom, to show to mirror . The number in mirror will be 813 (not E18). But the line, of coarse, will be on top . A vertical FLIP .

^This

What do you mean by reflect? This video describes what a reflection actually is. A reflection is an image reversed in the direction perpendicular to the mirror surface. Saying “mirror’s reflect” is really just saying they flip in the z-direction. Asserting that mirrors don’t flip is incorrect.

@@andrewthenoble a mirror reflects the exact image that's in front of it. Mirrors dont flip. The end.

Raul J You’re completely missing the point. How would you describe a reflection without using the word “reflect?” This video is describing what it means for something to be reflected. Your comment is the equivalent of saying the definition of a reflection is “a reflection.” That doesn’t explain what is physically happening.

@@andrewthenoble what? Lol. I said "reflects the exact image". The content is about reflection, so therefore there is no reason for me to be more specific about a mirror. Also, i'm not going to waste my time with someone who spells "your" the wrong way. Enjoy your day.

+Ed C23 Remember, just because it's a mirror it doesn't mean you should do everything it says. Also try telling it to do some things for you too, in exchange.

+circ1ebreaker Right? Reflections are such freeloaders if you let them. Tell it to kill ITS whole family for a change.

Sometimes it tells me to burn things... :(

may I suggest that you...GET THE HELL OUT OF YOUR HOUSE!!!

My mirror is named, daniel, he says damn in excitement whenever i bury the bodies :) my mom says i'm "special".

make sure you have clothes on of course.

Thanks man to tell that to a girl, as I wanted to. This video is a joke.

That's just changing the coordinate system. It's still flipping in the Z direction.

Thank you.

no mirrors don't flip anything mirrors actually reflects light where it hits it

😂

my mirror can flip an 8 ball to a kilo ok, hand me my beer back.

I'm gonna watch GTAV fails now

+DiamondHype lol

haha

LOL this made me crack up

Ereht did uoy tahw ees I

¿ǝuop noʎ ǝʌɐɥ ʇɐɥʍ

DX now uoy ,ko

HOW???

PKBeast +1

Same exact thought. Word for word

I like the girl.

this is from old Royal Institution Christmas Lecture. i think it was 80s or 90s

My first video too. I think I broke my brain.

Thank you!

Physics Girl That was really good pedagogy. I thought it was mostly going to be a talking explanation, but the real life context really helps. The length & speed was basically perfect... MinutePhysics goes a bit too fast for the novice at times, and sometimes drawing, just can't pedagogically do things that seeing an actual video of the phenomena can do i.e. you actually flipping a shirt around, or in the universe flat video pouring tea into a cup. However, at other times animation & diagrams can be irreplaceable, providing a value that only it can do best - like drawing attention to specifics & simplification, or for providing a viewpoint perspective on things that is much clearer. I.e. positional astronomy stuff like celestial sphere concept. However, what minutephysics is absolutely unrivalled for is in recapping concepts & meshing them all together quickly. Maybe having more links to other youtubers, for more detail on the concepts, is what he should do more often. Veritasium seems to do what you do well, as well, and I think derek's got pedagogy [of science concepts] in the form of video pretty damn well figured out in terms of youtubers. Others are good like vsauce & numberphile type channels but derek seems to balance the real life & diagrams pedagogically carefully & effectively depending on the concept. Works well for areas of natural physical science phenomena anyway. And another thing that the best youtubers do well is elaborating on the natural physical science vocabulary vs everyday language. Sapir-whorf hypothesis is important in explaining concepts which has pre-existing everyday associations. Here's a neat paper I found on that web.phys.ksu.edu/papers/2003/narst03-vocabofintrophysimpactonlearning.pdf). p.s. I just wanted to say henri (thanks for the name), is an absolute master & carefully considers the diagrams, he stretches it to the absolute limit, to almost real life/computer generation 3d. I.e. Some people do diagrams but they may draw a side view which can be ambiguous but his are very carefully considered drawing some in 2pt perspective, when necessary.

Time2Splitt Thank you for that analysis! I have (of course) watched many videos from both Derek and Henry, but it's nice to see what works and what doesn't from a fresh set of eyes.

Time2Splitt goddamnit Google, I can't upvote comments in mobile RU-vid.

Time2Splitt Are you sure you ain't Sheldon Cooper or Stephen Hawking

thank, what she was saying looked pretty stupid to me considering that mirror don't do a thing besides reflecting photons

sou ma I've seen this question like this posed many times, and slowly but surely I've grown an intolerance of them. It's verging on science, but all throughout you have "logic" that is just utter nonsense,

Toron she addressed that in the video.

+type moon I'm aware.

I'm a mare.

Glad you liked it. This was the best explanation I could find before making my video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-UkV87XC15DQ.html, but I still had a few questions.

Exactly what I was thinking. I could instantly relate as soon as she mentioned flipping through herself in Z. :)

This comment needs to be higher up.

You never tried Google?

@@davecarsley8773 People sometimes get busy with life and don't get around to getting all the little questions they have answered as soon as possible.

but i still dont know why i get 7 years of bad luck if i break one...

I have what's known as a "true" mirror: two mirrors that seamless intersect at 45-degrees. It corrects the z-axis inversion. I'm surprised she didn't use one in the lesson. When you look at it it shows you exactly how you look to other people. You stand in front of your objective self. It's like seeing yourself in a photo or video, but in perfect, life-size, natural 3-d. And as up-close as you dare to get -- which is VERY freaky. You wanna know what you look like when someone moves in for a kiss? Yikes!). I like to surprise my students with it at the beginning of the year. Being early teens, they cannot get enough of the effect. A couple of them in every class come in early enough to adjust their hair. Why not see it as it really looks?

@@carlodave9 The correction done by the 45 degree mirror can be quite confusing to some people though. If you ever want to see a woman get angry with a mirror, ask her to apply her makeup using a 45-degree corrected mirror... unless she is the really adventurous sort, she will never want to try that again. LOL There's also the coordination issue... like when one tries to fly a remote control model aircraft, and loses their orientation once it's turned around to come back towards them... as such, this is where trainers tend to crash a lot. A simpler example would be when you indicate to a friend that he or she has a piece of icing on their left cheek, you will generally point to your right cheek indicate it. And even though you may actually say "left cheek" , they will almost always still check their right cheek because you pointed to your left one, unless you're compensating for this response by pointing to your right, which most people innately do... due mostly to our conditioning from normal single-plane mirrors, but also because that is how we relate, as this young lady in the video describes our left/right biased mental symmetry.

+MrZY97 imagine if you could look through the paper that says food as you are facing it away from you towards the mirror, from behind the paper you would see what the mirror sees. that doesnt sound helpful though

Elijah Lee That makes sense! Does that mean the mirror flips everything the way you said it flips "FOOD" on the paper?

+Elijah Lee EXACTLY, well said. Heck, try writing FOOD on a clear piece of plastic and hold it facing away from you. What do you see?

MrZY97 can you repeat the question?:p

Elijah Lee Haha so the way mirrors flip images is similar to the way "FOOD" is seen from behind the paper? Does this make it clearer :x

not left and right that is true, but they shift time however. lol. They merely reflect back relative to the viewer, left, right up and down

adaniel2929 If you flip finger to the guy in mirror he will flip you back.

they'll flip ya... they'll flip ya for real.

Vladimir Jocic Yeah it dont flip. If I scratch my left nut it wont look like am scratching my right nut in the mirror because its a reflection.

always wondered why that happens, why does the mirror choose that image and not the other way around, if things are equal whats the difference.

hogarth heathan, each time an image reflects it flops. With 1 mirror, the image flops once, and must rotate it the full 180°. With 2 mirrors the image is reflected twice, and each mirror only rotates the flopped image 90°. So 180 degrees of image rotation, but with two flops instead of one. This effect is exaggerated in the extreme when you bring the mirrors to a parallel orientation with the reflections facing in, then look into either mirror, at the reflection of the other mirror. As you bring the mirrors close to parallel it seems that there are endless reflections, and every other one is flopped.

That's not correct. With 1 mirror, the Z-axis is flipped. With 2 mirrors arranged as you described, the z-axis is still only flipped once, but now you are ALSO flipping the image horizontally - making you appear as you would to someone else, but your image is still wrong - flipped in 2 ways.

iPhr0stByt3 what the heck are you trying to say that I didn't already say? When looking into a mirror you are on this side not that side. We all get that, but the effect of your z(in front of or behind the mirror) axis is effectively cancelled by the two mirror arrangement. What you see is what a person opposite the mirrors from you would see if the mirrors were removed, your true image, not the incorrect reversed image a single mirror suggests.

So you could read stuff thru a Periscope, which has 2 mirrors, but the angles are vertical, not horizontal.

You had me until this: "If while facing a mirror, you simply turn to the right, suddenly the image of your right hand is not only on your left, but to the left of the image of your left hand."... If I turn right my right hand would be behind me, not to my left. Did you mean if you turn 180 degrees?

No I mean if you turn 90 degrees to the right, resulting in the mirror being on your left. That's what I mean.

Ah I see.

Yeah I kinda tossed that example in at the end, it wasn't very important so I didn't explain it very clearly.

the mirror reverses the front and the back but my question is does it affect our physical image in other words is that others see us the same way when we see ourselves

Karl Hendrikse you serious?

But it made sense!

It really didn't.

Honestly, I thought she really oversimplified everything.

+Kyle Amoroso I totally agree!

+Kyle Amoroso its a simple concept to begin with.

More or less what I was thinking. When she showed that she had in fact flipped the paper to show the writing to the mirror I was hoping she'd then point the camera through the back of the paper to show that the writing bleedin through the paper matched the reflection she could see in the mirror.

exactly! the same with writing food on a piece glass. if you look at it on the other side of the glass, it will be the mirrored word.

yeh but it only correctly reflects the back when you turn the paper horizontally, not vertically. ;/ Other wise the reflection would still be upsidedown. You're just demonstrating that it DOES flip the image on a single axis, not why... ;/

The point is that the mirror does no flipping on any axis, the light being reflected back in the exact same orientation it was presented to the mirror (assuming a flawless flat mirror), you just had to flip the paper (horizontally) for the mirror to reflect it back to you, so you turned it back to front from your own point of view (as the ink through the back of the page would demonstrate), if you flipped it verticallly instead then by definition you have got it into the same position as if you had turned it upside down and turned it horizontally to face the mirror, so the writing facing the mirror is now upside down and back to front, as is the writing in the reflection, and so too would be the writing seen through the back of the paper. So demonstrating both of those things with sufficiently see-through paper, or sufficiently bleed-through-able ink, would clearly show that the reason why it appears to flip the image, is because you have flipped yourself or whatever you present to the mirror, so you are now viewing the thing as if you are looking through it.

Yeh but you could have just said "because when you face a mirror, your orientation is yaw-rotated 180 degrees from the mirror's which is where the difference comes from. If you turn your back to the mirror, you're seeing what it sees which is not flipped."

im symmetric at the z axis :v

Vitor Madeira Because we develop as embryos outwards from the spine. There are a few exceptions - some internal organs such as the heart are not symmetrical.

Neither are the balls.

Arie_ can you show a photo of the face of your other you? Also tell me about the private parts. I would also like to see how you have double feet.

Because we are created in God's image.

Take the mirror up from the floor and hang it on the wall?

What do you mean?

What do you mean?

when you nod your head yes but you wanna day no

That's true. The reason why we think letters Get horizontally flipped in the mirror, is because we think the 'original' image is what other people see, whose point of view is horizontally flipped from ours.

tripped me out too

+Appleholic1 You have obviously never had to explain things to a young inquiring mind. The visual analogy is brilliantly simple in a repeatable and reversible way to show what is happening with the reflection. This video wasn't made for people that understand the concept, it was made for those that don't. Just because you have a clear understanding doesn't mean everyone does.

+DIAFYFC And actually the only correct one in the entire video.

Yeah it is. That's what makes it a mirror.

James Loftus no. It has to do with the way photons are reflected off of the mirror. The "flipping" is an illusion.

SiriusMined Of course nothing is being physically flipped. But let's say you're looking north at a mirror. Something more south of you will appear more north of your reflection in the mirror. The image is flipped on the z axis.

Mirrors don't flip the X-axis OR the Y-axis. They flip the Z-axis. And yes, they DO actually flip the Z. They don't do anything to the physical photons, they do it to the emergent property of those photons: the *image*. The thing with mirror images is, they are 2-dimensional projections of a 3-dimensional object. It's essentially the same thing as looking at the back side of a 2-D computer sprite.

SiriusMined Okay then... the z-component of the velocity of the emitted photon is inverted, or "flipped", in relation to that of the absorbed photon.

Fred Bloggs LMFAO!!!!

That’s right!

Haha. True science.

Fred Bloggs Ouch!!

Of course there's a z axis. If you take the plane of the mirror as having an x (horizontal) and Y (vertical) axis, then the z axis is the depth between the observer and the mirror. (Include apparent depth in the mirror image of you wish.) Stating that there is no z axis is similar to saying that there is no distance between the observer and the mirror and the observer is 2D object. Clearly this is not the case.

@@paraicmcdonagh6062 Did you notice the part where you said "plane of the mirror"? A plane is a 2 dimensional object, period, full stop. IRL nothing is really 2 dimensional because that would require the (missing) 3rd dimension to be zero, but as a practical matter the reflection in a mirror all happens on that 2 dimensional flat plane. What you perceive as depth or distance in the reflected image is just a result of angles because angles are a large part of what or brains use to perceive depth/distance (and also speed). If the image you were looking at was created by replacing the mirror with a camera would you think the resulting picture had a z axis or would you recognize it as a flat 2 dimensional representation?

@@stevepseudonym445 No I didn't miss that part. What you are saying it's incorrect. Clearly there is depth between the observer and the mirror. Whether or not you accept that there is depth within the mirror reflection is irrelevant. Clearly you can draw a straight line at right angles to the mirror surface. This is a line along the z axis, not the x or y axis of the mirror plane.

@@paraicmcdonagh6062 I don't know what's so difficult, but you're confusing the real world outside of the mirror with the *reflection*. The real world obviously has a z axis. The flat reflection at the back of the mirror doesn't. Maybe it would help if you watched the video again. When she talks about the arrow pointing back at you what's actually happening is that the arrow is pointing up or down, and it's apparent length changes as a result of it's angle to the mirror. What you see in the reflection is width and (apparent) length. That's two dimensions.

@@stevepseudonym445 What's actually happening, is photons leave the surface of the observer (and the arrow they are holding), travel in the z axis (and also x and y) to the surface of the mirror and back to the retina of the observer's eye. The mirror isn't the only consideration. It's just one of the objects in a 3D environment. I don't know why it's so difficult for you to understand. LOL!