SciShow Tangents - Mirrors

Episode Date: January 11, 2022

We're back, baby! And we're seeing double! Ring in the new-ish year with us as we reflect on mirrors!Deboki is hosting a new podcast called Tiny Matters! It’s a science podcast about “the little stuff that makes the big stuff possible!” You can subscribe here! And be sure to follow her on Twitter: @okidoki_bokiHead to https://www.patreon.com/SciShowTangents to find out how you can help support SciShow Tangents, and see all the cool perks you’ll get in return, like bonus episodes and a monthly newsletter!And go to https://store.dftba.com/collections/scishow-tangents to buy your very own, genuine SciShow Tangents sticker!A big thank you to Patreon subscriber Garth Riley for helping to make the show possible!Follow us on Twitter @SciShowTangents, where we’ll tweet out topics for upcoming episodes and you can ask the science couch questions! While you're at it, check out the Tangents crew on Twitter: Ceri: @ceriley Sam: @im_sam_schultz Hank: @hankgreen[The Scientific Definition]Heliographhttps://www.theatlantic.com/photo/2014/04/world-war-i-in-photos-technology/507305/https://www.nps.gov/fobo/learn/historyculture/the-heliograph.htmhttps://books.google.com/books?id=RBC2nY1rp5MC&q=heliograph&pg=PA211#v=snippet&q=heliograph&f=falsePseudoscope http://waywiser.fas.harvard.edu/objects/3538/combination-stereoscope-telestereoscope-and-pseudoscope;jsessionid=ADBDCEF0ECA144094F58FDB5779EB61Bhttps://digitalcommons.bucknell.edu/cinematic/3/https://books.google.com/books?id=0_QMAAAAIAAJ&pg=PA146&dq=pseudoscope&as_brr=1#v=onepage&q=pseudoscope&f=falseEtalon  http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/fabry.htmlhttps://www.sciencedirect.com/topics/physics-and-astronomy/etalonshttps://www.osapublishing.org/ao/abstract.cfm?uri=ao-5-6-985Reflecting circlehttps://amhistory.si.edu/navigation/type.cfm?typeid=5https://royalsocietypublishing.org/doi/10.1098/rstl.1801.0019Pictures: https://en.wikipedia.org/wiki/Reflecting_instrument#Reflecting_circles[Trivia Question]James Webb Space Telescope mirrorshttps://webb.nasa.gov/content/observatory/ote/mirrors/index.htmlhttps://spaceplace.nasa.gov/telescopes/en/[Fact Off]Enantiomers (mirror versions of chemical compounds)https://spinoff.nasa.gov/Spinoff2004/ch_4.htmlhttps://www.smithsonianmag.com/space/must-all-molecules-life-be-left-handed-or-right-handed-180959956/https://www.diabetes.co.uk/blog/2015/06/the-version-of-sugar-that-wont-affect-your-blood-glucose-levels-and-why-you-cant-have-it/https://www.wired.com/2003/11/newsugar/The Venus Effect (mirror sight-lines) https://www.bertamini.org/lab/venus.htmlhttps://www.semanticscholar.org/paper/The-Venus-effect-in-real-life-and-in-photographs-Bertamini-Lawson/c6d67537323365e8fdae3c7e1b02635c7b1901aa/figure/3[Ask the Science Couch]Super efficient mirrors https://www.scientificamerican.com/article/what-is-the-physical-proc/https://news.mit.edu/1998/mirrorhttp://www.cnn.com/2008/HEALTH/12/19/laser.surgery/index.htmlhttps://physicsworld.com/a/crystalline-supermirrors-cut-optical-losses/https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=14069[Butt One More Thing]Mirror test IBShttps://pubmed.ncbi.nlm.nih.gov/3617051/https://pubmed.ncbi.nlm.nih.gov/16258235/

Hello and welcome to SciShow Tangents, the lightly competitive knowledge showcase. I'm your host, Hank Green, and joining me this week, as not always, well, as always, is Sam Schultz. Hello. And also, subbing in for Sarah this week and helping us bring in the new year is our editorial assistant, Deboki Chakravarti. Hello. Also.

Ooh, ooh, ooh. Okay. I love that entrance for me. So the new year is here, but it's not. So it is for you listening, but it's not so it is for you listening but it's not for us sitting here hopefully everything has turned out okay there's there's a number of things that that could be curveballs um the biggest one in my head is that giant curvy ball the james webb space telescope uh and that that's gonna launch now as of this moment i don't know if debuki you've heard this december 25th.

Oh, it changed again? Yeah, because there's a weather delay. So, yeah. So, it is going to be, at the moment, a Christmas launch. You know why they really changed it from Christmas Eve? Because they were afraid it was going to hit Santa. Yeah. They don't want to hit Santa. Absolutely.

That was the real weather delay all along. Uh-huh. Yeah. So, he's done with his work. Presents are delivered. Time to make a telescope go to space. Uh-huh. I am terrified. Yeah, me too.

I made a video about the James Webb Space Telescope 10 years ago. And it was at a time when the telescope was having like a particularly rough patch. It had plenty of rough patches. But I remember hearing, because I wasn't thinking about that when I made it, but I remember hearing from my people at NASA and they were like, that was a really nice thing to see during a really difficult time at the agency. And I was like, holy crap. Oh, interesting.

I thought I was making a goofy video. We should all just pick a scientist to cheer on this week. Yes. Yeah. Adopt a scientist. Someone out there's got an experiment going badly. So that's, yeah. I mean, that's not a terrible idea.

I want to reach out to the person who studies daddy long legs or the people. Pick one. Pick a daddy long leg scientist and be like, you're mine. And I'm going to be following what you do. And I want you to send me an update every once in a while. I just want to know how it's going. Why daddy long legs? I don't know.

I was just picking something. There's got to be somebody studying daddy long legs. Deboki, who would be your scientist that that you would adopt it's a good question how about a plant scientist someone studying like a really cool plant who's going back in has spent their holidays with the trees and are now like crap i gotta go back to this thing yeah i got into this business because i like plants and i spend all day inside with this one plant yeah do you have a scientist you want to adopt oh heck i don't know um do flavor scientists i was gonna say some kind of food thing might be fun yeah the scientists of flavor town okay i adopt them all also all flavor town scientists what are they trying to develop a better a better artificial cherry

flavor are they out there yeah could that be a thing that exists yeah yeah they're out there i believe in you guys maybe not the most important work but right it would be meaningful to me that's the kind of flavoring that goes into cough medicine so what could be yeah more important very yes for the coffers out there i actually really hated cherries for a long time, specifically because of the Robitussin flavor. So I do think this could go. Cherries are so good. And fake cherry flavor is so bad. They screwed

up so hard. Yeah. Well, this is a podcast that you're listening to. It's called SciShow Tangents, and every week on this show we get together to try to amaze and delight each other with science facts while also trying to stay on topic. And the topic will be discussed soon. These panelists, Deboki and Sam, are playing for glory, but they're also playing for Hank Bucks, which I'll be awarding as we play. And at the end of the episode, one of them will win.

But as always, we will introduce this week's topic with the traditional science poem this week from me. 21 feet and four inches across. Anything less would be a huge loss. That seems exciting, but we have to face nothing that big could get into space. There's just not a rocket that wide in existence, so we need a little engineering assistance. How about we make it in three different parts? Each part folds up before it gets its start. But we need them to all be the exact same size, so instead 18 hexagons is the prize, each fitting together to make three big pieces that can fold so the mission's ability increases. And we need to find ways to make it lighter, too, and easy to change shape to focus

the view. Keep it cold so you can chillium. A great option is strong but light beryllium. And it has to reflect the right wavelengths of light so coat them in gold before polishing bright with all this together everything's clearer with this space telescope's new gigantic mirror the topic for the day is not the james of space telescope that might have been fun it's mirrors yeah that maybe would have been a really good idea oops oh boy anyway the topic for the day is mirrors mirrors are a very important part of telescopes, but also lots of other things. Deboki, what is a mirror? So a mirror is basically a surface that can reflect enough light so that you can actually see an image coming out of it. So everything is going to reflect light, but not everything is a mirror because not everything is reflecting enough light in a way like we can see an image as a result of that reflection.

Are you saying that like if there was a complicated enough, smart enough computer that it could like interpret the light coming off of my wall and be like, I can see Hank in there. I don't know. I don't know enough about how light would work to make that happen. I'm going to say yes.

Like if you had good enough eyes to collect the light yeah you could like everything would look like i know how it's being scattered by like all the imperfections because one of the things about mirrors that makes them good at being mirrors is they have to be very polished be extremely flat um and that's what why why most things aren't shiny it's because they aren't flat yeah so basically one of the problems is like your wall like if you've got like a white wall like it might bounce life off of it. But if you like look at a molecular level, like that wall is going to be super rough and bumpy. And so like light that is going at it, it's going to be bouncing off in all sorts of directions.

So like going to that like potential like computer, that super smart computer option, I think it's got to be really good at being able to like figure out what all that light scattering is doing. being able to figure out what all that light scattering is doing. Yeah. It has to know not just how bumpy the wall is, but every bump on that wall. And then it could do it. Yeah.

So you could actually probably, I think what you could do is you could get really funky possible images coming off of it. I think the likelihood that you would narrow in on the right image is probably really, really low. But I think you could probably get some cool like pseudo mirror images that way. I like it. I like everything's a mirror. If you know what the bumps are, that's my tagline. Well, I guess the other problem is that there are also materials that are going to absorb light.

And so that's going to be your other shortcoming in terms of being able to turn anything into a mirror. Because if it's absorbing the light, then you're not going to get that image right right and but in and those are the things that have colors yes ah so you're saying i can't turn a block of wood into a mirror this is this is terribleness yeah i mean you can polish it you can make it super shiny and so like maybe you'll see some reflection off of it right Right. But you're going to get too much like light absorbing into that wood to be able to turn it into a mirror. So you're saying I can polish a turd, but I can't see myself in it. Into a mirror. I think you could vote the turd metallic substance.

Yeah. All right. Yeah. All right. Sure. I can bronze. The term isn't, the phrase isn't, you can't bronze a turd. Because you can,

you can bronze a turd. That's totally doable. Okay. I mean, this gives me a sort of good idea. And so like that means that you can have like a piece of metal be a mirror,

which is what we mostly did a long time ago. How is a mirror made these days? Yeah. So in like way back, even before like we figured out that metals or i mean we probably already knew that metals were good but like natural mirrors like pools of water were super great if we wanted to look at our reflection narcissus style like just near in that pool and then stuff like obsidian and metals like we realized like hey we can use that to reflect a lot

of lights get our reflection and over time the two techniques that really helped us get better at making mirrors were glass blowing and metallurgy. So sometimes just coating one material with that shiny metal would give you kind of that mirror thing, like something that you could use to actually see a reflection. And I think one of the way we do it now is we use a glass or plastic and then we have these like modern techniques to coat these surfaces with the metal and that lets you see you use them create like you know even like a cheap plastic mirror i guess i knew that one of the things that um a question i get is can you make a metal so thin that you can see through it

and the uh easy answer to that question is those shiny sunglasses that everybody wears have a literal metal film that is so thin that you can see through it yep which is cool so the answer is yes though it would totally fall apart if it did not have that the backing of the plastic or glass of the lens yeah do we know where the word mirror comes from? Yeah, it's actually pretty easy, which is exciting. The rest of optics is not easy, but this is easy. So mirror comes from the Latin word mirare, M-I-R-A-R-E, which means to look at, or mirare, it's an eye at the end, which is to wonder at or admire um because that's what we're using the mirror for though weirdly in latin the word for mirror is speculum and that's why a lot of other

european languages have words from mirror that have more s sounds in them like espejo in spanish and specchio in italian okay this admire uh relation is really interesting to me so admire has a shared root with mirror yes cool well that means it's time to move on to the quiz portion of our show uh i've got a new game here it's called the scientific definition this is a game that we've played just once before and this time we're going to take a vocabulary tour of scientific instruments that use mirrors the rules are very simple I'm going to give you the name of a device, and you're going to attempt to explain what it does through the powers of your deductive reasoning. Now, whoever gets closer, by my very expert judgment, will win the round and

get a Hank Buck. And then, because I know all the answers, I will pompously correct you, and we will hopefully laugh together. So, round number one, we are going to talk about the heliograph. And what you are going to do is tell me, using your expert judgment and also improvisational skills, what a heliograph does. Oh, boy. Can we ask for a spelling? Is that a- Yes. H-E-L-I-O-G-R-A-P-H.

Air. It's got to be a sun thing. Heliograph. Hey sun thing hey hey hey don't give it to sam okay well we can thinking out loud you could think and think out loud you could give it give him something to work with maybe i know a lot of root words too hey come on i've been on this podcast for a long time well i mean you know you were thinking helium thinking helium. I know, helicopter. And helicopter. Yeah, sure, sure. Spinny.

I thought I meant air, though, not sun. Whoopsies. I should have let you. Yeah. Okay, so like the graph part, I feel like that means it displays some kind of information to you. But I still have a mirror. A heliograph determines the brightness of the sun on any given day. I like that.

I think that the heliograph is a tool to redirect sunlight onto other areas of a house or building or structure. So a mirror. Yeah, a mirror. I assumed that it had to be related to mirrors. Yeah, yeah, it's got a mirror involved. This is just a mirror, though. But then it was called a heliograph, and it used mirrors to turn the sunshine elsewhere. All right.

So yours is a redirection of sunlight onto a thing. And Sam's is measuring the amount of sunlight. Yes. I'm going to give it to Sam. You both said sun. I don't know that the sun is necessary, but it is more about information than it is about projection.

Though it's close because also you are a little bit right, Deboki. The goal of a heliograph, it's a mirror attached to a tripod or whatever thing was around. And it was used to send light-based signals across distance from 25 to 180 miles you could send signals by light using heliographs from around the mid-1800s to the mid-1900s with various mirror sizes and shapes and arrangements and lenses to

increase or decrease the dispersion of the light. It was mostly used in military applications, especially during times that had like clear sunny skies. So conflicts in Arizona between indigenous people and the U.S. military heliographs were used. So they figured out how to make a very narrow beam of light. It's tricky to intercept unless you were along that route. And then they basically would sort of like send Morse code signals with the light over long, long distances. Whoa, that's cool.

Kind of amazing. Basically like little lasers almost. Yeah. I feel like Deboki was more right than me, to be perfectly frank. I would also argue. In my favor. I mean, Deboki got exactly what it was. Yeah.

Okay. I'm going to give it to Deboki then. Thank you. If everyone agrees all right uh round number two this is the pseudoscope p-s-e-u-d-o scope what is the pseudoscope is it that thing that doctors wear on their heads with the mirror on it it can be that's what i'm saying it is i don't think i have a better answer than that. Maybe like a handheld microscope.

Handheld microscope. I like that. Yeah. Okay. Let's talk through what it is, and then we'll talk through who I think got closer. So do you guys know what a stereoscope is? I don't remember. It's like a thing you look at pictures and you can see them in 3D.

Exactly. It's basically like a Google Glass, Google Cardboard, and then you put a picture in there and it sort of like can focus each of your eyes on different images and your brain combines them into a 3D image. So that's what a stereoscope was and that came first.

And then we got pseudoscopes, which is a device that uses mirrors to switch the two images in a stereoscope. So the photo in the left eye is shown to the right eye and the photo for the left eye is shown to the right eye, and the photo for the right eye is shown to the left eye. And that is used to study how human vision works by messing around with it, especially how we perceive depth and understand physical space. So it was a scientific instrument used to understand our brains. And when you use the

pseudoscope, depth perception is reversed. So a rectangular pit like a swimming pool would look like it's sticking out of the ground instead of sticking down into the ground. This science-y way to say this is it turns elevations into depressions and convex into concave. And they were developed in the 1800s to study vision, but they kind of existed beforehand when people just messed up when they were arranging mirrors in binocular instruments like microscopes. Oh, shoot. So I feel like we should probably give that one to Depoki. Got the word right in there and not even close to what I said, so. Round number three, what is an etalon? E-T-A-L-O-N.

It's also called a Fabry-Perot interferometer, if that helps. Oh, okay. Thank you. So it measures something if it's an o-meter, huh? Yeah. You know what it could measure? What? How bright of a sunny day it is.

How about that? A tool for measuring the shininess of rocks. Wow. um a tool for measuring the shininess of rocks wow you're both so so far away this is gonna be hard to assign any points to this one oh shoot so uh adalon specifically are two mirrors that face each other so they're two parallel very reflective mirrors that can bounce light back and forth between them. And you can use that to help standardize light wavelengths to a very precise range based on what mirrors you use. And that is from the French Eidolon, which means measuring gauge or standard. It's used for things like single mode lasers, which are very narrow and bright. Spectrometers that can distinguish between really close spectral runs in chemistry labs and in telecommunications to make fiber optics work.

That is an Adalon. It's basically, they're two mirrors that face each other and they only, I think they only let pass like a bunch of things like bounce down and then they come out of it eventually and they have an extremely specific wavelength. So it's a device for creating very specific wavelengths of light. Got it. And we got measuring the sun or what was the other one? Measure the shine. I feel like Sam was closer.

He's involved light. Yeah. I think Sam's a little closer. I feel like you could put sunlight in there. Yeah. You could put sunlight in and then get something out. You're measuring a kind of sunlight or some kind of light. Okay, we have one more round. This is the reflecting circle. What do you think the reflecting circle is? And no using the same thing you said before because you're like the thing on the doctor's head. Okay, but what if it is a thing on the doctor's head?

Yeah, well, then you'll have to suffer. Ah, shoot. Reflecting circle. A reflecting circle. A reflecting circle. What does a reflecting circle do? What does it help you do? What problem does it solve? Oh, gosh.

I mean, all I can think of is it can solve what squares can't do. What? I don't know what problem it doesn't solve. Yeah, anything a square can't do, this circle can. Okay. I think that the reflecting circle is a way to light fires in the middle of the woods. Okay. Yeah, all right.

A reflecting circle is a big old circle of mirrors, and you put something in the middle of it, and you can see it a lot of different ways. Okay. I think that that one's going to go to Deboki barely just because the reflecting circle is a navigational tool. It's in the same family as a sextant and they use mirrors and lenses to help you measure the angular distance between two points of reference. Both of them are going to be celestial objects. I don't know exactly how sextants work.

But basically, it's a navigational tool. And I'm thinking Deboki is where I'm leaning because it's a way of surviving using tools. Oh, interesting. That does make sense. Like the circle, you got like navigation. I get where the circle comes in. Square could not do it. Yeah. How did we come out of that we came out of it with Sam getting one point and Deboki getting three

despite the fact that none of you had any idea what the hell was going on the whole time no we were very wrong I was just slightly less wrong yeah okay that was very fun. Shout out to Sari for designing a fun, fun game.

Next up, we're going to take a short break and then it'll be time for the fact off. Welcome back, everybody. welcome back everybody uh we are again sam with number one points uh deboki with number three but anything can change in the fact off in the fact off our panelists have each brought science facts to present in an attempt to blow my mind and after you have presented your facts i will judge them and award hank bucks to the one that I think is going to make the best TikTok. So hopefully you were ready for that. So, but in order to figure out who goes first, we're going to start off with a trivia question. We've been very excited about the launch of this James Webb Space Telescope for a long, long time because it's very exciting. We are excited, as previously discussed on this episode.

Telescopes with larger mirrors allow the observer to see more light, but launching such a big mirror into space is hard. If they just scaled up Hubble's 2.4-meter mirror into Webb's 6.5-meter mirror, it would be too heavy to reach orbit. So instead, they made Webb's mirror with beryllium to be one-tenth of Hubble's mirror mass per unit area. So how much does each of Webb's 18 mirror segments weigh? So there are 18 large mirrors, and I want you to tell me in pounds how much you think each one of those 18 things weighs.

So not all of them together, but just one of them. 200 pounds. 200 pounds. I'm going to go on the lower end i'm gonna go with 50 pounds did bogey it's 46 wow yes yeah they worked very hard to make these mirrors very light and they are big you would look at one and you would think i probably can't lift that and then you would be able to lift it which is pretty remarkable and then you get yelled at don't do that then you would be sent to prison so uh yeah yeah yeah so well done doboki that means that you get to decide who goes first um sam why don't you

go first i hate you so mine now is we're more in a spiritual sense than it is in an actual mirror sense. Forgive me. Doppelgangers, your twin from a mirror dimension, who's just like you, but different in some uncanny way. Generally, doppelgangers are the stuff of fiction, but compounds like salt, like amino acids, like any chemical compound,

have mirror image twins. So if you look at your hands, this is a way to explain it that I read, they look pretty much the same, but they ain't the same. Your thumb pokes out of a different side of each hand, and that's just the most obvious example of how they are not the same. Mirror image compounds, also known as enantiomers, thank you, smart people, are similar. They're made of the same stuff as a compound. Both are made of the same pieces, but they're constructed in opposite ways.

So like you have an acetic acid molecule, for instance, that has a bunch of hydrogens coming off of the left of the carbon and one that has a bunch coming off the right of the carbon. And in most chemical reactions, they act the same way. But in biological chemical reactions, like the stuff that happens in your body, they don't. And in fact, living things on earth, you both are nodding too much. You already know all this.

Living things on earth only use and produce so-called left-handed amino acids and right-handed sugars and all their natural processes. So if you made a bunch of sugar in a lab, you'd end up with 50, 50 left and right oriented sugar. But in nature you only find right-handed sugar. And there's not really a good reason for why that is except for that's just how we came out. So in 1969, the Viking 1 lander landed on Mars and on it were a handful of experiments to test for microscopic life in the soil. One of those experiments designed by Dr.

Gilbert Levin, basically mixed sugar with Martian soil and then measured for chemical byproducts of microbes digesting the sugar. But if life on Earth can only digest right-handed sugar, it's possible that life on Mars can only digest left-handed sugar. But if you just poured a bunch of sugar from like a box of sugar in your kitchen or whatever into the test from like sugar beets or sugar canes, you'd only end up with right-handed sugars because that's how the biological processes on Earth make. So for this experiment, left-handed glucose was made

and added to the experiment just in case that's what the microbes wanted. Oh, interesting. And guess what? By the metrics of this test, life was detected in the Martian soil. I remember this. However, these findings were dismissed by NASA because of other tests on Viking 1 that did not detect any life. But Dr. Levin still says that he found life on Mars.

It's been a heated thing. When they were like, we're going to do this experiment to show whether or not there's life on Mars. And then it's like, answer, yes. And they're like, wait a second, that's not. I don't like that. It could be explained other ways.

Yes, my thing was getting too long. So I didn't include that. You can read about it at your local library. Anyway, after all the Mars hubbub, Dr. Levin started messing around with left-handed glucose and found that he was feeding it to people, I think. And to his test subjects, the taste was indistinguishable from right-handed glucose. There was older literature that said that it was bitter for some reason, but that didn't seem to be the case. But the body did not process this sugar. That was the other way around.

So he figured it might just be the perfect alternative sweetener to put in to stuff that needs to be sweet. It's just sugar didn't taste, but it's not sugar. Unfortunately for him, the process of making left glucose and other left sugars is so expensive that according to some sources, I saw the end product costs 50% more than gold,

but maybe also fortunately sometimes mirror image compounds can be evil twins like the what is the word inontometer enantiomer yeah of thalidomide is what caused birth defects so it's possible that maybe a lot of exposure to left-handed sugar could have done something weird yeah and also i think since then it's been shown to be a laxative in high enough doses, so. Yeah, often that stuff you can't digest ends up having a laxative effect. I suppose that makes sense.

It'll just pour right out of your butt, huh? Yeah, and it like pulls the water out of your colon because it's like an increased concentration of sugar in one place. Right. And then you have a bunch of extra water in your butt.

And you can see yourself in the toilet if you look there. Yay, shiny. Well, Sam, you did a great short version of a chemistry lecture that Devoki and I have both received. Ah, shoot. Well, that's okay. Somebody out there is learning something. And maybe even given on a crash course. Yeah, yeah. Yep, indeed. But it is fascinating. And maybe even given on a crash course. Yeah, yeah.

The idea of indeed. But it is fascinating. And I wouldn't have thought about it as a sort of interesting thing that most people don't know about. I had no idea. I didn't know about left-handed sugar. And I didn't know that it was sent to Mars to do this test. Nor did I know that it was a potential alternative sugar. And as I was saying to you earlier today, Sam, I hate fake sugar tastes. So it would be great for me. I know that it was a potential alternative sugar. And as I was saying to you earlier today, Sam,

I hate fake sugar tastes. So it would be great for me. I know, I was thinking about that. Except for the gold part. Except it's really expensive, yeah. Yeah, I wanna know like how quickly they went from like making the sugar for Mars to being like, actually, we're gonna taste it.

Like we made this, we gotta eat it now. Yeah, I don't know. No, immediate. Deboki, what do you have? Okay. So, obviously, we all interact with mirrors quite a bit in our daily lives. We, like, might check out a reflection. We might, like, if we're driving, we might look in a mirror.

And also, as may be evidenced from some of what we've been discussing with trying to understand mirrors, we don't always understand them. So, for one example of just how bad humans can be at understanding mirrors, we can look to none other than the goddess Venus, because artists have been painting images of Venus for centuries. And one common pose has her staring into a mirror with her reflection visible to the painting's observer. And in general, when people tend to look at these kinds of paintings, they tend to say that Venus is looking at her own reflection in the mirror, except that that is physically impossible. I hate this. Yeah, like if you look at these paintings, I didn't really think about it until I was looking into this.

But the way these paintings are set up, we're not usually positioned directly behind Venus. We're not positioned in a place where we are seeing the same thing in the mirror as she is. So what we see in the mirror is different from what she's seeing. In fact, what she's probably looking at is actually our reflection or a reflection of the painter. And a team of researchers actually decided to test this out. They wanted to kind of verify that this is a real thing that people do and see kind of how it happens. So they showed people old paintings and photographs of a subject who's near a happens. So they showed people old paintings and photographs of a subject who's near a mirror and they asked people to draw the sight lines and like kind of say like, you know, like how do things reflect and then to also describe what's going on in the

picture. And no matter where the mirror or the subject was positioned, people tended to stick with the incorrect interpretation that the subject of the painting could actually see themselves in the mirror. And so the researchers call this the Venus effect. They're careful to note that this is like not actually an issue of the painting or like the artist's fault or anything. This is just about how we interpret these images of people looking at mirrors. And so it's not just restricted to paintings. They even tested it out with like a mannequin that like you could look at like in a mirror, like seeing what they're looking at. They tested out it out with a mannequin that you could look at in a mirror, seeing what they're looking at. They tested it out with photographs. And we can also see this

in movies. If you're watching a TV show or a movie where an actor or actress is looking at a mirror, we tend to interpret that as them staring at their reflection because that's what we see. But again, because the camera is not positioned directly behind them, that's like not actually what we're seeing. It's just that's how we interpret these images. Right. I mean, the thing is that in these paintings of Venus, so the reflection is looking directly into my eyes.

If you think about it, you know that she is not looking at herself because she's looking at us. So she's seeing us or the painter. at herself because she's looking at us. So she's seeing us or the painter. This is cool because I was primed to expect that she wasn't looking at herself. Apparently, if I had not been, I would have initially assumed that she was looking at herself. That's interesting.

I mean, this is troublesome. I was rooting for you, but this is a great TikTok. Well, they can both be great TikToks. I agree with that. Wow, it's so weird. So there's a lot of these images. Yeah, so I think Venus Effect just got the name because it's often, like paintings of Venus

have this pose so commonly, but it's really something you see in all sorts of paintings, movies, and stuff. Interesting. This one of Venus, she's actually looking at herself. So you can paint it that way. There's not a reason you can't. Yeah.

It's just often not done. So was this done intentionally? Were the artists trying to draw Venus looking at herself? Or were they trying to draw Venus looking at the observer? I think what they were trying to do is draw a painting of Venus with her reflection. And so I don't know that it's strictly supposed to mean that they were intending to draw one, like a specific narrative of what Venus is looking at. I think to me, at least the way I interpret it, and I guess this is where it gets very artsy and kind of open to interpretation probably.

But I think one of the ideas that the researchers talked about in their initial work is that what we're doing is we're actually interpreting these images. We're interpreting these images in line with a certain narrative that we kind of attach to the painting overall. So we think of this painting as a painting of Venus looking at her reflection, and so that's how we interpret it. I don't know if that's actually strictly what's happening, but I think that's one way to potentially think about what we might be doing. Interesting. So does this tell us anything about our minds?

Well, maybe. It's interesting because they tested it out with paintings, but they also tested it out with actually creating a 3D room where there is a person staring at themselves in the mirror or staring positioned next to a mirror. And it just seems to be that like we think if there is a person near a mirror, it's almost like we just assume that they're looking at their reflection. So I think like what it says about us is just that we're really bad at understanding mirrors. We kind of just seem to assume that a person near a mirror is looking at their reflection. But I don't know that there's a good deep psychological explanation. It just seems to be that no matter how much we interact with mirrors, we're really bad at understanding them. They are weird. So for example, my brain says that if I get closer or farther

from a mirror, I should be able to see more or less of my body. But that is not true. Yeah. They talk about this as well. Like, we don't understand what to do with the mirror. Yeah. Like, it seems like if I move closer, I should see less of me. If I move farther away, I should see more. But because as you get farther away, the mirror gets smaller from your perspective. It shows the same amount of your body.

Yeah. What the heck? Right? Is that true? It is true. I know. I didn't believe it, Sam, until somebody told it to me

and I was like, no. And then I went and stood in front of a mirror and I was like, Jesus Christ. Oh, no. Okay. I want to try it right after this. Yeah. Optics is not cool.

Yeah. Never been a fan. It's so cool and completely rude. It's very cool, but rude. That's what every physics teacher should say. Like Raphael on Ninja Turtles. Exactly. All right.

Oh, I have to choose. I think I'm going to choose the Venus effect. What? It has a great name. Don't you think all the teens on Tumblr or TikTok or whatever we're talking about need to know about the flipping around molecules? Come on. I don't know. I like that a lot too.

I do. I do. Do that one later. I mean, that one later. Yeah. I mean, it is hard,

Sam, but it's so fun to tell people that they're wrong about the paintings. They're looking at. It is. Do you know what she's looking at? You're wrong. All right. So that means final scores.

Devoki wins. And Sam, you get one extra point for introducing me to orange cream soda mixed with Dr. Pepper, which was delicious. Did you like it? I did like it. I thought I wasn't gonna like it. I poured it in and I was like, why did I do this? And then I liked it.

It was better than either of them alone. That does sound amazing. Yeah. Tasty stuff. It was. So, bonus point for that, but it wasn't quite enough to save you. And now, it's time to ask the science couch. We've got a listener question for our virtual couch of finely honed

scientific minds. It's from James on Discord who asks, how practically efficient are the most efficient mirrors at reflecting light? So obviously mirrors don't reflect light perfectly.

Can't, I assume. Just because nothing's perfect. But you you like if you're on one of those uh elevators where like both sides like it's mirrors on all sides yeah you can see that they aren't perfect because they sort of like get green and darker as it goes deeper in so that's the effect of the imperfection of the mirror reflecting all wavelengths of light. Oh, yeah. But to Boki, that's all I got. What do you got? Yeah.

So I have some numbers. So most good mirrors, they reflect around 80 to 90% of light. Oh, that's not very much. Yeah. But even like there are mirrors that can be as low as 60%-ish. And we're still like, that's a mirror.

Yeah, yeah. So I don't know if it's just like maybe you can't see as clearly. I'm not quite sure um but the rest of that light gets absorbed into the metal or transmitted through if that layer is like very thin cool um so but like you said like that that is why we can tell like some of the color of mirrors or like why we kind of assign that greenish color um it's also why like we kind of think of mirrors as sort of silverish in color because they're still not like perfectly reflecting all that light back. They're still like whatever kind of the initial color of that metal is there for us to observe as well.

There are mirrors that can be super, super high efficiency. They're like around 99 to 99.9 percent. But these are special fancy mirrors. 99.9%. But these are special fancy mirrors. They're used for optics and physics research or for medicine or military applications because we don't need them. We do not need all that light reflecting back at us in a bathroom. I don't need my reflection that clear.

Yeah, we don't need to be seeing that. And part of what makes them useful too for a lot of applications is they're reflecting not just like the light that we see, like visible light. They're also reflecting other forms of light, like other non visible light. So that's part of why, again, super unnecessary. I don't need to worry about all those wavelengths. And the James Webb Space Telescope, for example, is super like you look at it and you're like, that's not a perfect mirror. It's yellow because it's gold, but it's very good at reflecting infrared light, which is what it wants to do mostly.

Yeah. So like some of the applications for these mirrors, they're called dielectric mirrors based on how they're made. And so one military application, you can use them to reflect back enemy lasers. Surgeons can also use them potentially to very precisely. Reflect back. You just got to skip right over enemy lasers. Let's reflect back. You just got to skip right over enemy lasers. Let's reflect on the reflecting

lasers. You know, that's useful for reflecting enemy lasers. There are less militaristic applications too. You can use them

in surgery. Well, not you, but surgeons can use them potentially in surgery. Hank could use it. He'd just do a really bad yeah no i need some training yeah uh but yeah so you could use uh mirrors potentially to control tiny laser beams for surgery instead of using a scalpel so yeah lots of um uses for these super perfect mirrors super perfect mirrors you don't really think about the imperfection of mirror

because it seems like it's doing its job just fine. But big difference between one of those normal ones that I have and the ones that are used for enemy lasers. If you want to ask the science guys your question, you can follow us on Twitter at SciShow Tangents, where we will tweet out topics for upcoming episodes every week, or you can join our Tangents Patreon and ask us on Discord.

Thank you to at Air B Dragons, emily 17 and everybody else who asked us your questions for this episode if you like this show and you want to help us out it's super easy to do that you can go to patreon.com slash scishow tangents to become a patron and get access to things like our newsletter bonus episodes second you can leave us a review wherever you listen that uh is very helpful helps us know what you like about the show and also other people will know what you like about the show and finally if other people will know what you like about the show. And finally, if you want to show your love for SciShow Tangents, just tell people about us. I did not do that well.

Yeah, I'm always really bad at math. It's very hard. Deboki, what are you working on these days? Yeah, so I have a new science podcast show coming out in 2022. It's called Tiny Matters. I'm co-hosting it with Sam Jones. It's being put out by the American Chemical Society. And basically what we'll be talking about is all the little stuff behind big stuff that we know about. So stuff like how dinosaur fossils are

helping us understand the planet's futures, why it's difficult to make a vaccine against HIV. And so the trailer for our podcast is out now and you can look it up. It's Tiny Matters. And the first full episode will be coming out january 26th 2022 wow that's exciting i am and you are too at home aren't you opening up your phone right now and you're opening up your podcast app and you're searching for tiny matters right now and there it is and i'm following it did you do it at home well done thank you to bokeh for coming on coming on and also for all the work that you do on Tangents and etc. Thank you for joining us. I've been Hank Green.

I've been Sam Schultz. I've been Deboki Chakravarti. SciShow Tangents is created by all of us and produced by Caitlin Hoffmeister and Sam Schultz, who edits a lot of these episodes, along with Hiroko Matsushima. Our social media organizer is Paola Garcia Prieto. Our editorial assistants are Deboki Chakravarti. Usually, not really so much this time. This time it was Sari Riley, Emma Doster, and Alex Pillow. Our sound design is by Joseph Tunamedish, and we couldn't make any of this without our patrons on Patreon.

Thank you, and remember, the mind is not a vessel to be filled, but a fire to be lighted. But one more thing. The mirror drawing test is a psychological stressor in which someone tries to trace a metal star reflected in a mirror using an electric pen that buzzes when they go outside the lines. During this stress, people with IBS contract their colons more than when they're just chilling. Oh, my God. And this doesn't happen to people who don't experience IBS. Oh, my god. Wow. So this mirror test showed researchers that in IBS cases, using your brains to relax might also signal your bowels to relax.

I don't need this news. It's too much pressure. My colon's like, relax man, and I'm like, lay off. I'm doing my best. Don't be tracing any stars Hank

you'll be in big trouble oh god stressing me out just thinking about it