The Magic (and Mystery) of Mirrors

[@besmart]

I hope this video give you something to reflect on 🤓 Thanks for watching, I'm on Instagram and Twitter! @DrJoeHanson @okaytbesmart

[@businessbusiness5784]

First

[@Jumpathy]

Hey suckas

[@fep_ptcp883]

Joe, as usual, this was a well polished video

[@boomboomgames_]

ah yes, the dad jokes.

[@micahbirdlover8152]

@@businessbusiness5784 thank you it's okay to smart or me🤪

[@FrankLeeMadeere]

I always found it easier to imagine that every point in the mirror is just reflecting back what that point "sees", like a whole bunch of little lasers. Start with one point and work your way up. It explains every "weird" phenomenon perfectly once you can imagine it. There is no "flipping" or "reversals", just a true reflection.

[@JamesR624]

Thank you. Every time I see a "science" video about mirrors, even when the channel is usually quite intellectual, it suddenly feels like I am watching something out of Nick Jr. They make all these weird analogies to try to fill the 10 minute time slot when it's literally not that complex. It's just a point for point reflection most people by the age of 2 already understand intuitively. This video feels like if they tried to "explain" why red and yellow make orange but extrapolated irrelevant stuff to stretch it to 10 minutes. This felt like the most "filler" thing I have ever watched, and will only confuse people if anything at all.

[@GiraffeKing04]

@@ananas-007 yeah no, my uncle is still in prison for protesting at the start of russia "just moving troops" you're dooming them to life in prison if russia wins

[@Dragrath1]

@@JamesR624 Well the description based on a plane or axis of symmetry is generally how a mathematician or physicist would describe symmetry however as it generalizes much more broadly than the point to point symmetry concept does. Point to point symmetry is limited to a 2D reflection of a 3D world whereas axes of symmetry and their higher dimensional counterparts generalize to any number of dimensions. This is particularly important in physics where Noether's theorem tells us that for each such symmetry in nature there is a conserved constant in nature. Energy is the conserved parameter for time symmetry in the laws of physics. Momentum is the conserved quantity under translation symmetry of physics and angular momentum is the conserved quantity under rotational symmetry. Even the speed of light represents the angle between the spatial and temporal axes within general relativity which is why nothing can ever go faster than the speed of light since from a geometric perspective that very notion is absurd. When taken to a higher level of abstraction of gauge symmetries of the wave function (which means that you can arbitrarily chose a point of reference without effecting the results) it even allows you to derive electromagnetism and the other forces of quantum field theory without any additional information, The point is your "intuitive" point to point symmetry is a special case which distracts you form the true nature of symmetry which in turn allows all of modern physics to be derived from first principals at least in theory. The description given in science based channels is chosen because it is always true and arbitrarily generalizable to the nature of reality itself. Point to point translations are not generalizable like this as they represent a special case of a 1D axis of symmetry. Granted the point to point translation perspective is likely a better starting point for transitioning towards the general case of axes of symmetry but this description of symmetries in this video is more correct technically speaking though it really needs to be connected to the direct applications of these symmetries for it to really come together.

[@KitKatHexe]

@@GiraffeKing04 better to suffer the weight of what's right than to enjoy a comfort built on a mountain of corpses

[@GiraffeKing04]

@@KitKatHexe or, flea the country, we have no idea if he’s even alive rn.

[@Beryllahawk]

Spent half this video going "mirrors bend light" and you went a whole different way with the explanation. VERY interesting! I'll have to go and ah...reflect on what I've learned.

[@dentoncrimescene]

I was quite comfortable how mirrors work before I started watching this video, was then super confused for a while, then I ended up okay with it again by the end. Quite an odd experience.

[@erinm9445]

Same!

[@tiyam3219]

Same 😂😂

[@jbrown8601]

Same here, blew my mind.

[@_Amor_Fati]

wow, Yes! Mind blown again, PBS! 🤗 Thanks for the Top Notch content to questions my parents & teachers tried explaining to me as a child through my, "Why is the grass 🌿green, why is the sky🌤blue? Childhood Phase" Now as an adult, those questions re-piqued my curiosity, and you present it to us with perfection! Bravo! ❤🧡💛💚💙💜😘

[@Neptoid]

Try to know what is odd under other other transformations, btw we call properties that change under a transformation odd and if they are unchanged, even

[@Katiethewizard]

As a printmaker who always has to carve or engrave words/images backwards so they print correctly, I understand all too well

[@ananas-007]

⚠️THE WAR IS GOING ON⚠️ Please share this on any Russian sources: СЕЙЧАС ВАЖНАЯ ИНФОРМАЦИЯ: Я и все люди в мире которые хотят окончания войны просим вас об этом: Люди, надежда сейчас на Россиян. Сопротивление сильнее всего, когда оно идёт изнутри. Если вы можете, прошу, выходите на улицу, делайте хоть что либо, это может спасти жизни! Я знаю что сейчас вам тяжело как никогда. Экономика на голову рушется. И за неправильные слова у вас могут отнять работу, учёбу или свободу. Но если война продолжится, то они уже ничего не будут значить. Так что, пожалуйста, хотя бы расспростроняйте информацию, держать людей в неведении - это преступление против людских прав. Если вы сейчас не заговорите, то потом уже будет позно. Распростроняйте информацию. Прошу вас как обычный человек который страдает от войны. Ради будущего всех нас. Не молчите. Не верьте слепо источникам, даже мне. Старайтесь докопаться до истины своими же усилиями. Мир в ваших руках. Russian people don't have a clue about what's actually going on. It's a call for them to spread the information by any risks and by any possible ways. We need resistance from within to defeat Putler. I beg you, please share this!

[@HansLemurson]

You gotta mind your p's and q's!

[@bytekast]

@@ananas-007 no

[@SDRIFTERAbdlmounaim]

can you show me a few things you've printed ?

[@Hobo_X]

I have always felt that the mirror test is being far overly-exclusive. Cats don't pass the mirror test for example. Now this obviously isn't a very scientific example, but something I've always done growing up was whenever we would get a new cat, I would put them on the bathroom counter and see their reaction in the mirror. The "reaction" was almost always a complete lack of reaction. But if they saw any other cat in the room, they'd freak out because they haven't been assimilated yet. To me that has to be displaying _something_ about their brains, because how do they know not to freak out over their reflection?

[@garybartnik1509]

Perhaps they did not detect a cat scent from the image in the mirror, so they knew it was not a real cat. Gary in dreamland. Have a nice dream!!🙂☁️☁️☁️⛅💫

[@whoreslayer]

@@garybartnik1509 thanks 👍 you too buddy 😎

[@edgar-sama642]

Yeah, I think that it only applies to "sight" based species, but what about smell, or hearing based ones?

[@garybartnik1509]

@@whoreslayer 🙂☁️☁️☁️⛅💫👍👍

[@SupahGeck]

Yet another case of humans making tests that prove intelligence based around things WE can do really well. But if you were racing against a shark to navigate across the ocean floor using only the earth's magnetic field you'd probably feel pretty dumb.

[@manuelapollo7988]

I am a physics teacher and I have taught this lesson a few weeks ago. The book mistakenly say that the mirror flips left to right. I had to explain the students that no, it's not true. But the main lesson was how even simple phenomena can be very much counterintuitive.

[@CineSoar]

I think an excellent demonstration would be to write the word on a transparency. When you hold the transparency so that the word looks correct, it also looks correct in the mirror. Because what is on the left is reflected directly back from the left. It is not flipped at all. If you think of the words on your t-shirt. It isn’t as if you walked through the mirror and then turned to face yourself. It’s as if the first parts of you to contact the mirror stopped at the surface and then, the rest continued into the mirror, stopping at its respective distance from the tip of your nose. You weren’t flipped left to right, or top to bottom, it is more analogous to being turned front to back. In lasers, we call this a time reversing mirror, because the first part of the wavefront to enter the cell, is the first part to reflect back.

[@katetoolate234]

The back to front flipping is very apparent to me when I try to put a hair pin or something on my head using a mirror. When I try to move to the right spot along my head, I usually end up going the wrong way. 😄 I saw this concept explained in another video before but this one covered more. Well done!

[@conlon4332]

To show a mirror writing, you flip it - from facing you to facing the mirror. It reflects what you show it - it doesn't flip it back. Write on a piece of paper with a pen and hold it up to a window, facing the window as you would have it face a mirror. Read it through the paper, and it's mirror writing. It doesn't reverse what it sees, it reflects it back as is, without changing it. The writing you show it is as it would look from the back of the page - you might be able to see both simultaneously if you use a felt-tip - and it's the same thing the mirror reflects back to you. If you write on condensation on a car window, it's a mirror image on the other side of the glass. If you write in the air, what the person opposite you sees is the same as what a mirror opposite you would see and show back to you. The same as if the person opposite you read writing through the back of a page you were reading. If you had see-through paper, such that you can see the writing from both sides, one side would appear as mirror writing. If you showed this page to the mirror so that the paper was orientated that you could read it, the reflection you could also read. Mirrors don't have their own left and right - unlike a person opposite you, your right is its right and your left is its left, it's not flipped, you're just so used to flipping it for another person's perspective, but a mirror's not a person. That's our problem. You show a mirror writing on one side of a page, and it doesn't read it, it shows you the writing as it would be if you could see it yourself through the page. Nothing is flipped, you just expect it to be, but a mirror doesn't have it's own perspective like a person or camera does, it uses your perspective. In a way, it enables you to see things, from your perspective, that you never normally could, like the other side of things from a side you never normally see them - as if you were looking at the other side of the object - say the sheet of paper - through it, rather than by turning it around to see that side, which reverses it when a mirror doesn't. I hope all this made sense.

[@etownshawn]

Always fascinated me as a kid at the barbershop, seeing 2 mirrors facing eachother & infinite reflections inside them. Also, I want to buy that over-sized alarm clock haha

[@agepbiz]

Thank you, but my brain still hurts

[@idraote]

This was far more complex than expected. Also, I tend to notice asymmetries in the human body. I zoom on them automatically. My OCD is not happy about asymmetry.

[@andoletube]

You may think you want symmetry because you are fixated on that, but there have also been studies that show people are disturbed by exact symmetry. People don't trust total symmetry in humans. So take comfort in the fact that even if you got the symmetry you think you want, you wouldn't be happy with it anyway because you wouldn't be able to trust that person.

[@wirataadidharma]

Have u seen symetry asymetry meme of person's portrait, where the name is also flipped too. I feel uncomfortable with the symetry faces, they're not right.

[@Markle2k]

Perfectly symmetrical faces slip into Uncanny Valley. Even the most symmetrical of faces when artificially mirrored by software look not only different from the full natural face, but begin to look artificial. This tends to trigger everybody.

[@Ghost-Raccoon]

We think that a mirror flips left and right, because if the see a person in the mirror, we expect that person to have walked behint the mirror and rotated 180° around the vertical axis. Because this is how we expect humans to rotate. Based on this assumption, that there is a normal person "in" the mirror that just rotated, we think that the mirror person has left and right reversed. We cannot imagine flipping front and back of a person.

[@Ghost-Raccoon]

@@RecoveryHacker No. You can use one eye. Doesn't change a thing.

[@johnwalter8139]

Yes, I think this is more realistically accurate and why our perception is that the person has left and right flipped. In a non-reversing mirror, the reflection is actually rotating 180 degrees to get it right, and if you turn it sideways it reverses up and down

[@jiujennie]

I work for PBS and I've never been more proud to help this organization TAT

[@abhinavjha1886]

You are a great content creator never disappoints .

[@salsal435]

This video almost broke my brain ☹️ Thank you for your amazing content!!

[@tonydai782]

When you look at your reflection, your left side stays on the left and your right side stays on the right, just as the top and bottom do, the only change is that the reflection faces the other way. We flip the image horizontally to align it with ourselves, flipping the left and the right. If we instead flipped the image vertically you would see that up and down would be swapped, while the left and right would still be in the same direction. The reason we don’t do this is because we generally don’t flip vertically but can spin around horizontally.

[@TPPMac1]

I always have issues with the "recognise self in mirror = sense of self" hypothesis. It's just too anthropomorphic. Most of the animals we apply this to have very good senses of eyesight. I'd like to see experiments where we "record" smells and fire them back at, for example, a dog and see if they can pick themselves out of a range. Would that mean they have a sense of self also? Would it mean we don't if we cant recognise our scent as us?

[@Estebanbermu98]

Anthropocentric I think is the correct word but yes I agree

[@micahbirdlover8152]

@Martha Speaks I liked that show Martha speaks not your name but nice name tag🙂

[@micahbirdlover8152]

@Martha Speaks I like your picture 😊

[@IntenseVisuals]

This was way more interesting than I thought it was going to be.

[@ananas-007]

⚠️THE WAR IS GOING ON⚠️ Please share this on any Russian sources: СЕЙЧАС ВАЖНАЯ ИНФОРМАЦИЯ: Я и все люди в мире которые хотят окончания войны просим вас об этом: Люди, надежда сейчас на Россиян. Сопротивление сильнее всего, когда оно идёт изнутри. Если вы можете, прошу, выходите на улицу, делайте хоть что либо, это может спасти жизни! Я знаю что сейчас вам тяжело как никогда. Экономика на голову рушется. И за неправильные слова у вас могут отнять работу, учёбу или свободу. Но если война продолжится, то они уже ничего не будут значить. Так что, пожалуйста, хотя бы расспростроняйте информацию, держать людей в неведении - это преступление против людских прав. Если вы сейчас не заговорите, то потом уже будет позно. Распростроняйте информацию. Прошу вас как обычный человек который страдает от войны. Ради будущего всех нас. Не молчите. Не верьте слепо источникам, даже мне. Старайтесь докопаться до истины своими же усилиями. Мир в ваших руках. Russian people don't have a clue about what's actually going on. It's a call for them to spread the information by any risks and by any possible ways. We need resistance from within to defeat Putler. I beg you, please share this!

[@TMtheScratcher]

Actually I was more interested in the question from the beginning. Our body is symmetrical and this is astonishing if you try to imagine yourself from the perspective of a cell. The machinary behind cell differentiation which determines what a cell has to be is incredibly accurate to create symmetrical animals at this and even larger scales

[@KryssLaBryn]

The really wild part is that we're only bisymmetrical *externally.* Our organs are only vaguely laid out symmetrically at best. Like, most people know that their heart isn't symmetrical, neither itself, not in its placement in our torsos; but despite how they're usually portrayed, our lungs aren't, either. Our left has two lobes, but our right has *three.* And don't even get me started on our stomachs or livers! Our kidneys, bladders, and reproductive organs are pretty bisymmetrical. But especially considering how much we are on the outside, it's pretty weird to think how much, inside, we *aren't.* :D

[@TMtheScratcher]

@@KryssLaBryn yeah that's true.I'm wondering right now how symmetrical our blood vessels are

[@ExtremeMadnessX]

@@KryssLaBryn Because for surviving isn't important to be symmetrical inside but outside, you need to have symmetrical legs and hands and eyes and ears to survive (long enough to reproduce).

[@Metalkatt]

Your hair part was throwing me off in the first segment. It and the way you tend to quirk a half-smile put my brain on edge, thinking that something wasn't quite right.

[@zestyorangez]

It's no longer merely okay to be smart. It's now a command.

[@actualzelda]

lol

[@corviraptor]

5:55 mad props for using a blackwing pencil for style points

[@HoD999x]

I was missing two things 1. Mirror image of letters written on transparent 'paper' 2. Talking about the fact that we cannot describe which side is left, we have to physically show it

[@bytekast]

I gotta buy one of these double-reflection mirrors (the one that doesn't "reverse" the image). I want to know how other people see me. Also it looks pretty cool to have one around.

[@aisekaisebc]

Flatland, A term coined by Edwin Abbot. But something about Joe’e delivery and flat pun reminded me of Carl Sagan. Keep up the good work, it’s always fun to watch you deconstruct a concept and explain it so everybody can enjoy learning it.

[@claudioantonelli2725]

Mr. Abbot wishes a word, concerning the description of Females in Flatland.

[@shixxor]

How I came to understand mirrors was... write a word on a transparent sheet and look at it.... now stand in front of a mirror and you can read the word exactly the same. Now turn it around like you would on a normal opaque sheet of paper to "show" it into the mirror and it's reversed. The mirror doesn't reverse anything, you do.

[@ThomasGutierrez]

Front/Back is the mathematic transformation (x,y,z)-->(-x,y,z) across the mirror's yz plane. However, the symmetry of our bodies surely plays into how our brain prefers to interpret mirror images: weakly broken L/R symmetry, strongly broken Top/Down, and weakly broken back/front but with a strong facial filter. Our brains would rather visualize the creature in the mirror to be one that is like us but with L/R reversed rather than a creatures whose back looks exactly like our front. However, with a little creative noodling, one can make up other biological symmetries whose brains might favor a Top/Bottom flip or front/back interpretation.

[@mateoacevedocontreras6087]

The mirror that maintains left and right is the craziest sorcery I have ever seen in my life.....

[@MedlifeCrisis]

Hope this video goes chiral 👉🏼👈🏼🙌

[@besmart]

👏

[@micahbirdlover8152]

@@besmart I loved this video 🥰

[@fireriffs]

Another way to demonstrate this is to write on a transparent page, like the old overhead projectors used to use, and face front away from you. You can see through the back that it looks like it does in a mirror.

[@Markle2k]

You are seeing two separate sides of the object then. The mirror is showing the side you can't see otherwise.

[@fireriffs]

@@Markle2k Yeah, but the point is it shows that nothing is being flipped. That a looking in a mirror isn't the same thing as standing in front of someone and looking at them. You can see that the light is simply bouncing back exactly as it was received.

[@Markle2k]

@@fireriffs Here's a further exposition that I posted elsewhere. Get a thickish piece of relatively transparent material (glass/plexiglas/perspex) and write a word on it on the side facing you. You will not only see the word reversed left to right, but you will see the word is on the far surface of the material in the image presented to you by the mirror. A sock being pulled inside out is a very poor analogy.

[@AmnonSadeh]

Exactly how it's demonstrated in a video by minutephysics: kzbin.info/www/bejne/Z6WXlYKGrbCaqLs

[@luisiriano]

I watch your videos when i feel sick (like right now) and it helps me feel better

[@QuietStormP]

Thanks for a new video! My son and I haven’t seen a new one in a while. Can’t wait to watch this with him.

[@ananas-007]

⚠️THE WAR IS GOING ON⚠️ Please share this on any Russian sources: СЕЙЧАС ВАЖНАЯ ИНФОРМАЦИЯ: Я и все люди в мире которые хотят окончания войны просим вас об этом: Люди, надежда сейчас на Россиян. Сопротивление сильнее всего, когда оно идёт изнутри. Если вы можете, прошу, выходите на улицу, делайте хоть что либо, это может спасти жизни! Я знаю что сейчас вам тяжело как никогда. Экономика на голову рушется. И за неправильные слова у вас могут отнять работу, учёбу или свободу. Но если война продолжится, то они уже ничего не будут значить. Так что, пожалуйста, хотя бы расспростроняйте информацию, держать людей в неведении - это преступление против людских прав. Если вы сейчас не заговорите, то потом уже будет позно. Распростроняйте информацию. Прошу вас как обычный человек который страдает от войны. Ради будущего всех нас. Не молчите. Не верьте слепо источникам, даже мне. Старайтесь докопаться до истины своими же усилиями. Мир в ваших руках. Russian people don't have a clue about what's actually going on. It's a call for them to spread the information by any risks and by any possible ways. We need resistance from within to defeat Putler. I beg you, please share this!

[@Brandyrose111]

What’s funny is I was just thinking about this the other when I was brushing my hair. I have a cabinet mirror next to the big mirror. And I swung the door open so I could see it’s reflection of me in the big mirror and thought “Huh, so that’s how people see me.” I also had a picture of someone and put it up to the mirror and thought “wow that’s how they see themselves. Which was so trippy because they looked backwards to me”. Loved the video btw, it’s like I sensed it coming. 😆👌🏻💙✨

[@b1ff]

It might help to realize that ordinary mirrors simply reflect light back to the source in straight lines. Mirrors don’t really reverse anything, they just reflect the light that hits it straight back to the object in front of it. The reason the pencil pointing towards the mirror appears to point away from it from inside the mirror is that the tip of the pencil is closest to the mirror both in front of the mirror and in the apparent reflection. If you hold your hand up to a mirror, you can draw straight lines across to the mirror, and those perpendicular lines will touch the mirror hand in exactly the same place. If you put your hand flat against the mirror, every point palm-side will touch the same points on the mirror palm-side. And if you look at the back of your hand against the mirror, it will appear to be the same as the palm-side of the opposite hand.

[@tonyippolito7580]

I understand what's going on, and yet my brain is still blown away by the word flip you did.

[@omarellahi2422]

Do I love this guy. The way he explains is awesome. And I am left wondering why does what he says sounds so familiar

[@itisyerdad]

That intro had me cackling. Such a dorky intro. I loved it.

[@ananas-007]

⚠️THE WAR IS GOING ON⚠️ Please share this on any Russian sources: СЕЙЧАС ВАЖНАЯ ИНФОРМАЦИЯ: Я и все люди в мире которые хотят окончания войны просим вас об этом: Люди, надежда сейчас на Россиян. Сопротивление сильнее всего, когда оно идёт изнутри. Если вы можете, прошу, выходите на улицу, делайте хоть что либо, это может спасти жизни! Я знаю что сейчас вам тяжело как никогда. Экономика на голову рушется. И за неправильные слова у вас могут отнять работу, учёбу или свободу. Но если война продолжится, то они уже ничего не будут значить. Так что, пожалуйста, хотя бы расспростроняйте информацию, держать людей в неведении - это преступление против людских прав. Если вы сейчас не заговорите, то потом уже будет позно. Распростроняйте информацию. Прошу вас как обычный человек который страдает от войны. Ради будущего всех нас. Не молчите. Не верьте слепо источникам, даже мне. Старайтесь докопаться до истины своими же усилиями. Мир в ваших руках. Russian people don't have a clue about what's actually going on. It's a call for them to spread the information by any risks and by any possible ways. We need resistance from within to defeat Putler. I beg you, please share this!

[@rakshitgv]

6:46 When you point north, the image in the mirror also points north relative to the north, south, east, west in the image formed in the mirror though(not relative to you). So technically, mirrors don't flip anything on any axis right??

[@lachimolala819]

I was about to say the same thing. He made both remarks relative to "his side".

[@johnmcgimpsey1825]

When you say "relative to the...image formed in the mirror", I think that you're also rotating your mental construct. There is only one actual direction for north (into the mirror in this video), so the pencil in the image does appear to point south. For the "person in the mirror", however, they reverse the names of the directions, but they see exactly the same flip - their pencil pointing "image-north", and the "real" pencil pointing "image-south". The way I think about it, since the mirror is a flat plane, the image has no depth at all. The apparent depth is due to the flipping along the perpendicular axis.

[@michaelguthardt327]

Or another way of thinking about it is that it flips everything. Your compass is flipped on both axis relative to the you in the mirror. It’s obvious that left-right appear flipped in a mirror but forget that the direction we are facing is also flipped. Top-bottom don’t flip because we are both vertical- put the mirror on the floor on the other hand…

[@ananas-007]

⚠️THE WAR IS GOING ON⚠️ Please share this on any Russian sources: СЕЙЧАС ВАЖНАЯ ИНФОРМАЦИЯ: Я и все люди в мире которые хотят окончания войны просим вас об этом: Люди, надежда сейчас на Россиян. Сопротивление сильнее всего, когда оно идёт изнутри. Если вы можете, прошу, выходите на улицу, делайте хоть что либо, это может спасти жизни! Я знаю что сейчас вам тяжело как никогда. Экономика на голову рушется. И за неправильные слова у вас могут отнять работу, учёбу или свободу. Но если война продолжится, то они уже ничего не будут значить. Так что, пожалуйста, хотя бы расспростроняйте информацию, держать людей в неведении - это преступление против людских прав. Если вы сейчас не заговорите, то потом уже будет позно. Распростроняйте информацию. Прошу вас как обычный человек который страдает от войны. Ради будущего всех нас. Не молчите. Не верьте слепо источникам, даже мне. Старайтесь докопаться до истины своими же усилиями. Мир в ваших руках. Russian people don't have a clue about what's actually going on. It's a call for them to spread the information by any risks and by any possible ways. We need resistance from within to defeat Putler. I beg you, please share this!

[@chadjmoore]

Great delivery!!! Always enjoy how you break down a concept. much appreciated!!

[@wholeNwon]

I think the "secret" of the appeal is his exaggeration of the movements and facial expressions that we all use when conversing with one another. We don't have to read as much into body language because there is less subtlety than in real life. Makes us relax.

[@Jordizzan]

I have never imagined a mirror is another person looking back at me. Like what.

[@claudioantonelli2725]

Great work, keep doing that. Btw. my Cat got spooked by your audioFX around 2 mins 😄

[@Yathuprem]

Awesome video as always, remind me so off the old physics girl video.

[@masteranakin8827]

I already know how mirrors work but this channel is so awesome so I wanted to see how they explained it

[@ananas-007]

⚠️THE WAR IS GOING ON⚠️ Please share this on any Russian sources: СЕЙЧАС ВАЖНАЯ ИНФОРМАЦИЯ: Я и все люди в мире которые хотят окончания войны просим вас об этом: Люди, надежда сейчас на Россиян. Сопротивление сильнее всего, когда оно идёт изнутри. Если вы можете, прошу, выходите на улицу, делайте хоть что либо, это может спасти жизни! Я знаю что сейчас вам тяжело как никогда. Экономика на голову рушется. И за неправильные слова у вас могут отнять работу, учёбу или свободу. Но если война продолжится, то они уже ничего не будут значить. Так что, пожалуйста, хотя бы расспростроняйте информацию, держать людей в неведении - это преступление против людских прав. Если вы сейчас не заговорите, то потом уже будет позно. Распростроняйте информацию. Прошу вас как обычный человек который страдает от войны. Ради будущего всех нас. Не молчите. Не верьте слепо источникам, даже мне. Старайтесь докопаться до истины своими же усилиями. Мир в ваших руках. Russian people don't have a clue about what's actually going on. It's a call for them to spread the information by any risks and by any possible ways. We need resistance from within to defeat Putler. I beg you, please share this!

[@jennyneon]

On the other side of a mirror, there's either your own self, or Candyman.

[@mencibenci]

yes, I also saw Feynman’s video where he poses the “why do mirrors only seem to flip left and right but not top and bottom?” question, thank you

[@cannedflea1335]

You're philosophising every thing . 👍

[@cinnamonsugarcourtney6073]

... when did the channel change names from "It's Ok to be Smart" to just Be Smart? Have I missed a few vids somehow?

[@keppycs]

yes you have

[@cinnamonsugarcourtney6073]

@@keppycs actually it was more like I just didn't notice until now, lol. I figured out it was the Team Seas plastic video when it changed, it's just longer between videos than most channels I'm subscribed to.

[@chrisg3030]

2:02 "Why are only the left and right flipped. Why aren't my head at the bottom and my feet on top?" But they are - when you stand on or by a horizontal mirror instead of the usual vertical one. A vertical mirror flips left and right, but not top and bottom. A horizontal mirror flips top and bottom but not left and right. There's only one flip at a time, and it's essentially the same flip. We just use different word pairs for it under these different circumstances.

[@Mr1fish2fish]

Here is a trick with mirrors that I learned from interpretation in my understanding from the scriptures of the Holy Bible: Using a light illuminator place a larger enough X-ray image on the light, and using a mirror examine the X-ray by looking at the reflection of the X-ray in the mirror. You will notice that one way the X--ray is facing is a perverted image, and turning the X-ray around on the light will show the reflection of the X-ray as if being able to see straight through the patient. Right is right and left is left, front is front, and back is back in the straight-on X-ray; and, left is right and right is left, front is back and back is front in the perverted image. All you have to do is turn the X-ray around on the light to see the image in corrected format on the mirror. Thanks.

[@Polymathically]

Huh, this was pretty interesting. I think I'll spend some time reflecting on it.

[@mbkrazer4765]

Amazing video, thank you joe. Loved how you explained it using North and South ♥️

[@OslerWannabe]

A much more teleological explanation of the symmetry mechanism behind mirrors' apparent reversal of left and right but not up/down is this: when we compare our image in tthe mirror to our conception of how we look, we do so by mentally placing the two images side-by-side. And we accomplish this placement by mentally walking around behind the mirror and standing next to the reflection, not by floating over the top of the mirror to stand upside down next to the reflection. Tnis description is really just another way of acknowledging our saggital symmetry.

[@hunterdouglas9765]

“Let’s say that this side of the mirror is East” I see someone has heard Feynman’s explanation ;) For me, the thing that made this phenomenon clearest was Physics Girl’s video with the gloves.

[@Markle2k]

Every couple of years some science explainer will break this one out for people who haven't heard or seen it before.

[@twilongenbone]

This video honestly deserves way more views i dont get how the youtube algorithm prevents it from reaching more people

[@phamchidat2126]

Great video as always, thanks Joe ^^

[@ananas-007]

⚠️THE WAR IS GOING ON⚠️ Please share this on any Russian sources: СЕЙЧАС ВАЖНАЯ ИНФОРМАЦИЯ: Я и все люди в мире которые хотят окончания войны просим вас об этом: Люди, надежда сейчас на Россиян. Сопротивление сильнее всего, когда оно идёт изнутри. Если вы можете, прошу, выходите на улицу, делайте хоть что либо, это может спасти жизни! Я знаю что сейчас вам тяжело как никогда. Экономика на голову рушется. И за неправильные слова у вас могут отнять работу, учёбу или свободу. Но если война продолжится, то они уже ничего не будут значить. Так что, пожалуйста, хотя бы расспростроняйте информацию, держать людей в неведении - это преступление против людских прав. Если вы сейчас не заговорите, то потом уже будет позно. Распростроняйте информацию. Прошу вас как обычный человек который страдает от войны. Ради будущего всех нас. Не молчите. Не верьте слепо источникам, даже мне. Старайтесь докопаться до истины своими же усилиями. Мир в ваших руках. Russian people don't have a clue about what's actually going on. It's a call for them to spread the information by any risks and by any possible ways. We need resistance from within to defeat Putler. I beg you, please share this!

[@_Amor_Fati]

Wow, Yes! Mind blown again, PBS! 🤗 Thanks for the Top Notch content to questions my parents & teachers tried explaining to me as a child through my, "Why is the grass 🌿green, why is the sky🌤blue? Childhood Phase" Now as an adult, those questions re-piqued my curiosity, and you present it to us with perfection! Bravo! goodvibes❤🧡💛💚💙💜😘

[@SunsetDragon]

9:37 Actually, this same experiment was done on ants, and they rubbed themselves, not their reflections. It was done with Manta Rays and dolphins, too. Dogs didn't react, but they don't rely on sight; when dogs were put in a similar situation but with smells, they, too, showed they knew they were different, somehow. Extremely interesting video!! I shall show off my new knowledge tomorrow.

[@airplanegeorge]

I could never seem to remember pie, until now, thank you!

[@luketurner314]

Corner reflectors, like those left on the Moon by astronauts, are 3 mirrors at right angles to each other so a laser will reflect back in the direction it came from, regardless of the angle between the corner reflector and the laser. Similar concepts at play. Also, when you look at someone else in a mirror, they see your face in roughly the same spot of the mirror as you see theirs. Geometry is amazing

[@tiffanymarie9750]

I still think the mirror self-awarenes test is only useful in assessing animals that primarily use eyesight to interpret their environment. For animals that use eyesight only to compliment their main sensory input, like scent or hearing, it makes little sense to expect them to use a mirror for self-assessment. And that's not even considering that some animals might just find mirrors too boring to care about, for whatever reason that makes sense only to them.

[@notabot117]

For example a cat may not react to it's reflection at all, but will attack a stranger cat which it doesn't know, which may say something about them.

[@tiffanymarie9750]

@@notabot117 yes! My cat sees her own reflection every day and has 0 reaction to it, but she treats other cats like the Ultimate Enemies if they even dare meow where she can hear them.

[@notabot117]

@@tiffanymarie9750 Cool!

[@saityusufbulur3366]

In the 3-dimensional plane, the y-axis represents verticality (up-down), the x-axis represents horizontality (left-right), and the z-axis represents linearity (forward-backward). A standard mirror inverts the image in the z-axis only. Therefore, when you look at the mirror, you don't see your head down and your feet up (image will not change on the y-axis) or when you hold an apple in your left hand, in the mirror image you don't see that apple on the right (image will not change on the x-axis), but when you point forward with your hand the mirror image will point backward (image will be inverted on the z-axis).

[@Abell_lledA]

One doesn’t experience self transcendence, the illusion of self only dissipates • 🎈

[@gbzzlqbjavat]

At 6:43 when u point north if u only look at the mirror your mirror self is still pointing at the north card

[@amitaischlesinger9016]

Great intro man!!!

[@TheyCallMeNewb]

This was excellent. It maybe the case that a modicum more on stacking in the visual field would help. Looking out a window at a landscape, things closer are 'lower' in one's visual field, while things farther are 'higher'. The north/south divide here was an allusion to such; and the flip we would swear occurring, owes it's existence to the same phenomenon -- with right and left (or alternatively, east and west) having nary a vote.

[@jeremyp7013]

Dude you just went way way up in my awesome book. The Voltron in the background is epic. I have 4 myself including the newer 2 foot and 6in diecast.

[@thomaskn1012]

Joe says that when he looks in a double mirror, he sees himself as others see him. However, when I see him do this, I see Hank Green in that double mirror. That’s crazy amazing 🤩

[@CODE7X]

Omg very very very thank you for this topic

[@chrisg3030]

1) A vertical mirror reverses left and right, but not top and bottom. A horizontal mirror reverses top and bottom but not left and right. That's the symmetry. Check it out. Put something asymmetrical in front of you on a shelf and slightly above your head. I used a coffee pot with the spout on the left. Don't look frontally into the mirror, but hold it out to your left (or right) with the plane vertical and positioned to get you an image of the pot from an angle, but still see the real pot as well at the same time. Resulting image has the spout on the right, but the pot is right way up. Then hold the mirror out to just below (or above) the coffee pot with the plane horizontal, again positioned to get an image of the pot and see the real pot too. Resulting image: spout on the left, but pot upside down. 2) But you don't want to talk of left/right or up/down image reversal? Fair enough, but let's be consistent and also disallow image flip between into the mirror and out of it. The mirror pencil is pointing away from mirror Joe just as the real pencil is pointing away from real Joe, so no reversal there either. In fact there's a simple rule applying to all directions, axes and orientations: nearest to the nearest, farthest from the farthest.

[@Ashlynescreator]

I think of mirrors like an object/person falling face first, flat into perfect snow or something that would leave a distinct impression. When the object/person gets up, the imprint left would be the mirrored reflection of whatever hit it. When you look into a mirror, you see what the ground would ‘see’ right before it got flopped onto 😁

[@goldenart1215]

I can respect the use of a blackwing during the pencil demonstration

[@dan_youtube]

You are a champ for making this video!

[@Lowenaaa]

I need to point out that the mirror test for animal is too much anthropomorphic to say with confidence only few species recognize themselves. How do you do the mirror test with a dolphin or a manta ray for example ? They don't have hands !

[@pablodmdp]

Which axis us inverted on a mirror: x, y or z?

[@saityusufbulur3366]

Answer is z, it inverts forward-backward.

[@EzekJohnson]

Amazing video. Really love it. God bless you

[@StormyTalks]

Nice new channel name!

[@spencerkapp8034]

Hey Joe, I clicked like at the "Plane existence" pun, just thought you'd like to know ❤️

[@johanneslettinghvilborg2443]

Joe just casually ripping that cone apart and continuing his explanation is priceless.

[@wholeNwon]

You realize, of course, that it was pre-cut.

[@johanneslettinghvilborg2443]

@@wholeNwon I know, just caught me off guard😅

[@wholeNwon]

@@johanneslettinghvilborg2443 Yup, his presentations are good. Grammatical mistakes irritate but that's just me.

[@siddhik4131]

just want to know which one is correct? mirror image or back camera image🥺 Amazing content🙌

[@KryssLaBryn]

Wow. That must makes it kind of depressing that ants also notice the mark on themselves and try to clean it off!

[@lesleyghostdragon3149]

The tiny hands outtakes 🤣😂🤣😂😅😅😅

[@beatrizpaniagua7806]

the pencil example was really helpful

[@leifodoyle]

Strained a muscle rolling my eyes at that intro 😅

[@timvangrijs2095]

Before watching most of the video, I think the reason why mirrors seem to flip things is this: Imagine your looking through an object, from behind, and seeing the front. Now you can't actually do that, so if we put a reflection in front of the object then it's as if we were looking through said object.

[@playgroundchooser]

I would also recommend The Science Asylum's video on mirrors for the physics behind this. Really cool too!

[@lukec2342]

Another theory of de Selby’s was that mirrors held the secret to eternity. His starting point was the reflection that, “[i]f a man stands before a mirror and sees in it his reflection, what he sees is not a true reproduction of himself but a picture of himself when he was a younger man” (O’Brien, TTP.5). This is due to light travelling at a fixed speed - thus the image must be of a (very slightly) younger man. de Selby claimed that by utilising this insight and creating a huge array of parallel mirrors, he succeeded in seeing his own face as a boy of twelve.

[@xXJ4FARGAMERXx]

I find it way easier to think of it as if somebody took an image of you with that image having a see-through backside, and put it on a canvas, and you are just looking at that image from the back side.

[@berryman5145]

Last episode about reading, this episode he mixes left and right. I insist, next episode should be about dyslexia

[@vortexx5007]

Very interesting continue your good work !

[@prschuster]

Actually, when a person turns around and faces you, they are rotating on a vertical axis to reverse right and left. That's why we cross our right hand over to the left when we shake hands. Since mirrors don't do this, and we are used to seeing people face us, we assume that the mirror is doing the right/left reversing.

[@prschuster]

@@marcosolo6491 Yes, I wondered why up and down weren't reversed in a mirror, and that helped me realize that right and left weren't really reversed either. The thing that confuses most people is why writing appears to be reversed in a mirror. It eventually dawned on me that we reverse the writing ourselves by holding a sign away from us to see it in a mirror.

[@jahosaphat]

I love this channel.

[@KaleemLmar]

When you make a simple thing ultra complicated 😂 thanks, really enjoyed it.

[@davidwimp701]

You destroyed my favorite bar bet. Thanks a lot.

[@knotshure8806]

Sagan is proud of your use of flatland

[@MrFireball619]

I loved this Joe!

[@robbabcock_]

Great stuff as usual.

[@Infrared73]

Now I’m curious about different animals interactions with mirrors. Elephants for example.

[@rokzcoban4394]

Listen Joe, I've got a question do we see your reflection on the mirror reflected as you see in real time through the camera lenses (KZbin video) or not? 🤔

[@PMA_ReginaldBoscoG]

When a dog poses its human palms touching each other, we all know that it's time to sing Dorime.

[@EAAUDITS]

Hey matey good effort ! Shame we dunno how mirrors work but i borrowed a clip of this & my viewers asked...12:11 why is woody sitting in a ...watering can on the edge of the desk? And was he put there deliberately as it kinda looks like he should be in the mirror . But he aint! More i find out about mirrors, more questions it raises - even the woody angle . cheers!