The first 1,000 people to use the link will get a 1 month free trial of Skillshare: skl.sh/thescienceasylum09221 *Correction:* The segment about safety hammers has been removed from this video. Some safety hammers do actually work very well. Thanks to diligent commenters, I've since done an experiment and released a correction video: ruclips.net/video/0tmLh_eSpQU/видео.html *Clarification:* The side windows and _rear_ windshield are tempered. The _front_ windshield is annealed. Sorry for any confusion.
are you familiar with a strange experiment i saw a loooong time ago on a youtube video where - IF i remember correctly- the setup was two perpendicular polarized filters which of course resulted in black (no light passing) but then when adding a third filter in series, light magically appeared again!! I really hoped you would touch onto it cause i cannot remember the explanation! Thank you for the video anyway
@@sadderwhiskeymann I don't think there is an explanation... just another mystery like quantum entanglement that everyone thinks should be impossible. Would still love to see a video if he hasn't already.
4:25 That "chip" in the edge of the protractor is where the plastic was injected into the mold. That's why the stress is oriented to it. 4:35 That "crack" likely indicates that the plastic was injected near the hidden upper corner of the triangle, flowing around both sides. The "crack" is where the 2 flow fronts came together. Yes, I spent a few years in the injection molding industry.
@@ScienceAsylum Yes, as jursamaj points out, it's not a crack but a knit line. They are usually not a problem if the moulding tool and the moulding process are done well, but they can still be a line of weakness that may need to be considered in critical applications.
Thanks for the injection molding tidbit. I would guess that quality control inspectors though (not engineers) use the polarization in production runs, if at all. Engineers would use it it for design. Although I've seen it used in research papers (scientists) on stress concentrations which might then be referenced by engineers for design.
Injection molding of plastic is now so ubiquitous yet it still seems like materials sorcery when closely examined. Same feeling you get when you make your own nylon. Mind blown.
@@JohnDoeHZ In my (admittedly limited) experience, polarimetry isn't very useful in production facilities, because most plastic parts aren't transparent. There is a lot of information we used based on such research, but I don't recall my plant even having any polarimetry equipment.
Hello. Nick, I did not expect this topic here on the channel but as an engineer for material science I aprove! I would like to ad a short explanation how tempered glass is made and how it works, for people who would like to know/understand. Very hot glass (the car window!) is quickly cooled from the outside. When this happens the outer parts of the glass starts to quickly cool and when things cool they generally shrink a bit. No problem yet because most of the body of glass is still hot and can easily adapt to the shrinking outer layer. But soon the inner volume starts to cool down too and at that point the outer layer is stiff and can not easily change. But the inner parts need to shrink! (The atomic forces who hold the material together are very powerful and demanding) What happens is that the inner volume contracts but the outer layer can not move and this causes the outer layer to be compressed (more than it wants) and the inner volume to be pulled apart (because the outer layer does not move much). So why does this help against damage? Home experiment! Take a bunch of pillows and put them together on the table. Punch them and watch them fly through your room. NOw have another person take the pillows and press them together with both hands. Punch the pillows again and.. the pillows stay where they are. The compression forces in the outer layer function like the hands of the person holding the pillows. To "push the glass apart" you need to overcome these forces first which makes tempered glass much more resistant against damage. I hope this helps.
Thanks for the extra detail! (Also, I want other people to love polarizers as much as I do, so the glass thing helps make polarizers relevant to people's lives.)
The sharp point tools actually work quite well, your problem is your glass isn't secured, and just flexes and bounces away. In a car, the glass is secured by the doorframe, with extra pressure from the water pushing in. There's lots of youtube videos of people testing tools, most of them work just fine, with the best having a spring-loaded punch similar to one you'd use to mark metal prior to drilling.
^agree to this with a ton of experience behind it. As a firefighter, taking tempered glass is done often on vehicles. A lot of tools that folks expect to readily break glass doesn’t often work but the easiest victor against tempered glass is always a small, focused point.
It reminded me of an episode of Shark Tank where someone first wanted to show how easy it was to break through a door, but humorously failed to to so because the door was secured to a movable metal frame instead of an actual wall.
"Light is literally all we can see" is so simple a statement that it sounds silly. But since I've been going through your videos on cosmology I've gotten a handle on dark matter and understand that light doesn't interact with everything. It's... uncomfortable knowing that some ideas that we take for granted (like light being the mechanism through which we observe ALL things) hide ridiculous facts about how the universe really works.
Technically, the only thing we can ever see is the electrochemical patterns moving around in the visual cortex. It's so strange to Conceive that we don't see "out", but everything we see, all of our surroundings, even the sky, is built within the mind based on sensory input. When you see something "over there", the distance between you and that object is probably real, but it's perceived within the confines of your skull. Even the position of yourself, your body, and it's location relative to the environment, is a projection of what may or may not exist "out there". It really messes with the mind! Lol!
@@bryandraughn9830 Very true and to make that more obvious, make sure to understand that there is no brown or magenta in the color spectrum (let's call it a rainbow). Colors (by that I mean the sensation we call colors) are made up by our mind. Not to mention that you perceive different colors depending on the words you have in your language.
We can easily extend this to "almost everything we can see is electromagnetic fenomena". We only know about gravity (apart from touch, of course) because the fotons expose the objects positions in the space due reflexion or absorption (hence the acceleration too). Moreover, Touch is also an electromagnetic phenomenon, LoL
Took me quite a few years to find out not everyone can see stress-patterns without any tools. Turns out only a very small percentage of people can actually see them. Needless to say, I got even more interested in them! Opticians use polarizes all the time to check if the lenses in your glasses are mounted properly!
Are there any artists that paint with that in mind, so people would need polarizers to properly see all of the painting, while a very small percentage of people would see that naturally?
I trained myself to see Haidinger's brush, which is a visible manifestation of linearly polarized light that you can see without a polarizer. It looks like a very faint yellow and blue bow-tie pattern near the center of your field of vision--you can see it by looking at a white LCD screen and gradually tilting your head, so the pattern changes enough that your brain won't edit it out. The blue parts lie along the axis of the electric field, and the yellow parts along the axis of the magnetic field. Once you know what to look for, you can see it in the sky, because that light is somewhat linearly polarized.
I recently finished a first year module in Material Science and we literally did this exact experiment! Your videos were a huge inspiration for me to study an undergraduate course in Physics. Thank you so much!
Sandwiching something in between two polarizers is an useful tool to pathologists since it allows them to differentiate between different types of microscopic materials based on their molecular isotropy (or anisotropy). Like, it is used all the time in microscopic tissue sections to detect amyloid, a class of misfolded protein that causes amyloidosis. Also there are uses of polarizing microscopy in geology to tell apart different rocks. You could do an episode on such practical uses of polarized light microscopy. It could be interesting, at least to me.
I'm pretty sure you struggled to crack the tempered glass because you allowed it to move, preventing the kinetic energy from turning into pressure (stress). When you hit the corner, the glass was pinned to the floor at the contact point, it couldn't move, so all the kinetic energy was turned into pressure energy, exceeding the internal allowable at that point.
you are partially correct . due to how tempered glass is made the edges of the glass cool down faster than the rest of the piece making it ........ less tempered . hitting tempered glass edge on can break it just as easy as annealed glass .
Unknown to most of us, humans actually do have some capacity to tell polarized light apart from unpolarized. A blank sheet of paper will simply be white, uniformly and equally, no surprise there. But on a standard LCD or OLED monitor showing a blank white canvas, by really focusing and also tilting your head every so often, you can see a blob of yellow and blue in the shape of a bowtie. It's slightly different from person to person, some people see patches where the screen is slightly darker but don't see the colors, some people do see the colors with no change in brightness, and sometimes the effect can randomly disappear.
Thanks for letting me know how to experiment with this phenomenon using just my sunglasses and a pc monitor! On the other hand, my wife does not appreciate it greatly because I am searching through the kitchen for every transparent bowl and gathering them on my desk for inspection.
Tip. If you break a spark plug and collect the broken ceramic pieces that result, simply toss them at a tempered window, the window shatters with hardly any impact at all. Something about the harmonics I suppose. But just a little shard of that broken ceramic casually tossed at the window and it shatters. Might be worth looking into and doing a video to confirm exactly how that works.
Always love your vids. You always tend to explain things in a way I can always understand which is sometimes difficult to find. And sitting down for a little science lesson kinda reminds me of the old days with Mr. Wizard when I was little. Keep up the great work!
This *really* makes me want to see the Slo Mo Guys revisit the Breaking Glass video with polarizing filters. I wanna see those colors change *as* the glass breaks.
playing with polarizers for the first time in physics class was cool. if i recall, a really cool object to look at under this effect is a prince ruperts drop.
We've used this technique to find defects in door glass for residential ovens where I work. That tempered glass has to be perfect, or it can shatter during cooking cycles. Don't want that to happen in somebody's kitchen.. There are some REALLY cool stress patterns in that glass, too. You'd never know without using a polarized filter like this.
I recognise those patterns in the Plastic equipment (protractor, rulers etc.) we had in High School. I wonder if there was a enough Polarisation going on in my glasses to account for this. Nice to finally have an explanation for what it was.
I worked for about 6 years with Alvin and Mortimer Marks, the inventors of polarizing films. Amazing the things that can be done with polarizing light, including making old time 2D movies into 3D movies, polarizing photovoltaics ( LUMELOID), stealth materials ( absorbing UV visible and IR light).
i really like your videos! I was going to do a linkedin post about this over the pandemic, but never got around to it. Couple of notes: "stress rings" are usually called fringes, like when looking at the moire effect and probably more technically correct to call strain rings since it's really the spacing of the molecules that alters the polarization of the light. You can actually buy off the shelf polarizers and materials that are basically calibrated to measure stress (you put the clear stuff over a thing and let it stretch) and a color coded chart is provided to quantify the stress of each color. Something not touched on your video, which I'm probably just telling you something you already know, but if you rotate your polarizer you can determine the directions of the stress in the material also. Birefringence is cool!!!!!!!!!!!! lol, nice job, you're doing awesome stuff.
Someone on s/askphysics asked how RUclipsrs like Veratasium and kurzgesagt were as far as videos go. Turns out Fermi labs, pbs spacetime, and you were in many of the responders top 3. I totally agree!!!
Not that any of them were bad rather being more convoluted for the sake of being convoluted. I'm sure most of us appreciate the clarity you and couple others bring. Easier to follow and understand which means easier to learn. Make like a fraction and simplify it lol.
to those curious, you can see polarized light yourself! physics girl has a video on haidinger’s brush, and its orientation in your vision is dependant on the polarization of light coming in. i’ve trained my ability to see the pattern enough that i can easily spot it in the clear blue sky 90° away from the sun, with the yellow lobes in the pattern pointing to where the sun is. you can also see it while looking through polarized sunglasses or an LCD screen as mentioned in the video here.
tempering glass is based on heat dilation (as opposed to metal where its about the crystalline structure grain size, glass doesnt have a crystalline structure), its heated up to a point where its sortof soft, and then cooled quickly. when its heated the glass dilates. when its cooled from surface first, the surface shrinks and hardens. after that the insides start to shrink too, but as they do, it drags the surface with it creating pressure and resulting in a denser surface. the cooling is done via pressurized air, and each of those dots is where an air nozzle is blowing on the glass.
Not sure if someone mentioned but windshields are made of laminated glass (1 piece of plastic sandwiched between 2 thin pieces of glass). This is important because of several factors, for example, if a rock or large object hit your windshield it won’t got through. Second the crack are lines so you can still see and drive. The temperate glass are used on side windows, that is why on smash and grab you will find a thousand piece of glass. On a car accident it allows the windows to be broken so you can be removed and also prevent sharp glass from hitting you.
I got some Oakley "fishing" glasses a few years ago. I don't fish, but the mirrored reflection was a and that's what I wanted :V Anyway, they have STRONG polarization and when pairing them with a motorcycle helmet it makes a cool but sometimes disorienting effect and ofc it's related to polarization! First off, cars change color with their angle to you. They're dark when coming at you, but shift to a lighter color as they approach 90° to your vision centerline. WATER is super trippy, and can appear doubled at some angles. I got prescription lenses so I hardly wear those glasses any more but I was walking my dog by a pond and noticed "holy crap! I can see all the fish!". Product functions as intended.
Cool! I just tried the glasses from the 3D movie theater and a cell phone as the source of polarized light and I can see stress in the plastics as well.
When I was a graduate student I lived in a literal hole in the ground--a studio apartment in my landlord's basement, with a sliding glass door in a small well below ground level. The door was double-glazed with tempered glass. One wintry evening, I was away from home when the temperature suddenly dropped from around freezing to down near zero Fahrenheit. When I came home, I found that the outer pane of the glass door had completely shattered into those tiny gravel-sized pieces. Thermal contraction had apparently caused those internal stresses to let loose and break the glass. Fortunately, the inner pane was still intact--but most of the shattered outer pane was still holding together loosely like a sagging vertical jigsaw puzzle that was obstructing the door from opening, so I had to knock it all away to open the door. Since the remaining pane was a less effective insulator, I had a chilly couple of nights until the landlord could get the door fixed.
Dang! I just Googled it and, apparently, it's not uncommon for doorwall glass to do that. Seems like maybe they shouldn't be using tempered glass in doorwalls.
Try having a monitor screen all white while in a dark room, have a pair of polarising lenses so you can see either the screen lit up or go dark, turn the lenses so it's dark, then grab a full clear water bottle and look at it through the lense. It looks amazing, looks like it's completely self luminescent, it'll look lot up and maybe you'll see other colours too
The sky can become kinda funky with polarized sunglasses too. I have noticed that if I look away from the sun ( north at noon in the northern hemisphere ) I can make the blue of the sky darken by rotating my glasses. The effect doesn't affect the look of the clouds so they pop out. Sometimes the effect doesn't happen and I have no clue why. Not even sure why the side of the sky away from the sun seems to have some polarizing effect.
I remember when I found on the street a broken game toy and I was able to take the screen apart. It had two transparent plastic pieces and I was astonished when I turned the two plastic pieces and it became completely black! 😯
On a side note car windshields are also laminated. When the tempered glass shatters it will stick to a stretchy substance and act like a net. Kinda like how softer steel is used to reinforce hard and brittle concrete.
To get a pretty fascinating Effect One needs a Pair Polarisation Glasses with round Glasses. Plop One Out, turn it a few Degrees - I have One at Horizontal and One 45° turned to the Left and plop it Back and One gets a 3D Effect in Reality or even more!! I know not really, but pretty fascinating and revealing! Works best during the Day :)
Haidinger's brush is crazy, it's something you can pretty much always see when you're staring at a computer screen, but unless someone tells you it exists, you probably never notice.
Did you know you can see UV light if your cornea is removed? See for example the painter Monet and how his paintings turned more blue after the removal of his lens in one eye. Monet's surgery meant the entire lens of his left eye had to be removed, leaving him with what's called aphakia, or the absence of an eye lens.
due to how tempered glass is made the edges cool down faster than the rest of the piece . hitting the glass edge on will break it just as easy as annealed glass . there is also an in between temp and plate (annealed) called heat strengthed that breaks similar to temp but in bigger pieces in a less chaotic fasion
Your tempered pane of glass was able to flex and absorb the impacts of your attempts to break it. :P Spring-loaded center punch is a cheap no nonsense emergency window breaking tool to keep in your car, and they absolutely do work. You can find 'em in any big box home improvement store. Just put the tip to the glass and PUSH. The spring-loaded impact mechanism does all the work. Takes very little strength, and you don't need space to wind up and swing. You don't need one of those fancy hammers unless you get one that also has a razor blade for cutting your seat belt strap, because seat belts CAN and sometimes DO jam and can't be unbuckled after a hard enough shock to the latch. Then it's worth it to buy the 2-in-1 tool so you don't have to think about digging out two tools and then using each one individually in an emergency when seconds literally matter.
I work with tempered glass all day, and boy am I glad this stuff has been invented. It's actually pretty fun to smash them on the ground with some PPE on. Very hard to get cut with this stuff (relative to annealed glass anyways).
The critical thing about breaking the tempered glass with the special pointed hammer is keeping the pane rigid, as if it were in a car door, yours flexed and dissipated a lot of the energy required at the point of the hammer. But otherwise, you're right, even a moderate bang on the edge will shatter tempered glass.
Hello Nick, I am new to your channel and find your detailed explanations extremely helpful! Would you mind doing an episode explaining why solids have color? I think there are a few different absorption mechanisms out there, like F-centre or van der Waals. A video about them would be amazing. Thanks in advance!
Thanks Nick Sir for making such amazing and complicate topic videos in such simple language I'm just in 12th grade and ur videos really help me a lot to deeply under my School textbook topics very well Usually school teacher just explain us how it works but not why only it works ☹️ U r the one who tell why only it works 😁 And not joking but I showoff infront of my friends about knowledge u gave to me especially 'Gravity is not a force'video 😂 But unfortunately I can't donate or join ur membership 😕😕 as i'm just 18 and my parents don't allow it too😕 But I watch ur videos regularly to gain more knowledge and commenting it just to tell u about that 😊😊
I was able to see these colours since I was a kid - without polarising glasses .. I assumed everybody could. I've also been able to see colour tones vividly where others were saying it's the same colour .. found out I'm a male with tetra-chromatic vision .. .. like a unicorn - discarded by society for being different .. .. I've learned to keep such things to myself and pretend I'm just ordinary Joe and use my not-so-super-powers to excel in life .. only to find that it pisses off people .. words like "who do you think you are?!" - echo in my not-so-identical memory .. .. oh well .. this is my life and it's beautiful.
Tempered glass also keeps you from getting blended by broken windows in a car wreck, or even just after hitting bigger bumps in the road. As far as those crash hammers go, the cheap ones are too soft to work because they deform slightly on impact, and shouldn't be allowed on the market considering the implications. Better ones will have hardened steel or carbide tips to focus the impulse into a smaller spot, and spring loaded center punches are very popular in emergency services for their ability to break auto glass in a controlled way
I don't understand this cheap "window breakers" are even legal. I'm going to look for a standard hammer design but with a pointy tip. Best of both worlds.
@@ScienceAsylum on a second thought, I 'm not convinced: why, in a car windshield, are the stresses so perfectly ordered in a lattice fashion. Moreover, why we don't need polarized light (as in the case of the ruler, with the LCD screen) but just a pair of sunglasses are enough??
Awesome video, I kinda always wondered about the spots, although I'm wondering if they might be from the molds themselves, seeing how auto glass is made, the molds are not what you'd think. They basically are a "Table" for lack of a better word, made of a grid of rollers that can be adjusted up or down to set the curve of the glass. And I'm thinking since the spots basically line up with the grid of the rollers if the glass cools faster at the contact points creating those stresses the polarization allows us to see. If that makes sense. Also As someone currently working in the auto glass industry as a tech, and for some time now, a few corrections: (to the best of my knowledge and understanding) A: On a lot of newer vehicles the front door glass is now laminated annealed glass, like the windshield. Meaning it's not going to break into a thousand tiny pieces, it will hold very strong even if broken and take a lot of effort to make fully fail. However the rear door glass, or backglass should be tempered. The way to tell is to look at the glass, there should (by law) be markings on EVERY piece of glass that states laminated or tempered along with other info like brand etc. B: Tempered glass is very unlikely to shatter from the force of impact going into a body of water, unless it hits head on, you should 100% have a glass breaking hammer similar to what he showed in your vehicle..period. You should also have a seatbelt cutter as well. C: As to the point above, the reason the hammer failed in your test is because it was not secured on the sides allowing it to dissipate the energy. These hammers are intended to break tempered auto glass in an emergency to gain access in, or out of the vehicle, that glass will be secured on all sides and will break. He is 100% correct that the edge of any glass is the weakest point. D: Not so much a correction but if you find yourself a body of water and sinking, the very 1st thing to do is roll down the window, power windows are not likely to immediately fail as there is water proofing, the inside of your door takes on moister normally. E: Purely a nit pick, there is only ONE windshield in a vehicle (unless it's a split windshield) everything else is a front door glass, rear door glass, Back glass, vent glass (opens as part of the door but does not roll up or down) quarter glass ( stationary glass that does not roll up or down, and does not open with a door.)
The clear ruler and triangle was a great example of internal stresses. I am taking a strength of materials course at my university right now. It was difficult to understand internal stresses and the concept did not make sense to me.
Have a look at tiny crystals in a microscope with a set of polarizing filters, one below the sample one somewhere above (I cut a piece of sunglasses to cover the occular lense). Crystals from the cubic system are somewhat disappointing - compared to other crystal systems. But it is a world of wonderful beauty.
Thanks! I still didn’t understand how more filters could produce more light? Because the first one is obviously already filtered out most light with other polarizations….
You actually can see polarized light without any tool. On a white computer screen is it visible when you tilting your head from one side to the other and back. In the center of your view will a blue-yellow figure apear, called "Haidinger brushes". It is very weak, but in front of the white screen clearly to see. On a very clear evening sky, maybe one hour before sunset you can see these Haidinger brushes 90 degrees offset to the sun likewise too. And even like on your computer screen you have to tilt your head from left to right and back again. The first try is maybe a little hard, but with some practice it will clearly appear.
This is similar to holding a powerful magnet near an old CRT TV and watching the electron deflection change as you move it around. Can't see the electrons but you can see the effects they have when diverted to the wrong phosphors. Edit: Note that the two phenomena are completely unrelated, but not as much as you'd think since electrons are waves too and have an oscillation "direction".
There is another way of shattering tempered glass. A broken piece of ceramic, like a broken spark plug, can shatter tempered glass when thrown. It might be the hardness of it combined with how small of a point ceramics can get when broken.
I've heard that striking tempered glass with the ceramic of a broken spark plug can cause the glass to shatter easily. But I have not tried to verify that.
Car window glass is mandated to be tempered by law to prevent injury during and after vehicle collisions. It has nothing to do with water. Car manufacturers nearly universally did this due to the obvious safety benefits and minimal additional cost well before mandated by government bodies.
I don't know which hammers you are talking about at around 07:00 but the small red hammers designed for emergencies definitely do work to break tempered glass quickly. If I had a car, I would have one of those near at hand.
You can see the stress rainbow on roolers without polar filter, yes it's easier to see with them, though. I saw those spots on a whindshield of a Trabant, don't tell me they used tempered glass on the whindshields. The whindshield are made with laminated glasses, normally, prewenting someone sheater it skull on them in an accident, and holding to shards togethet when the glass shateres.
It is (just barely) possible to perceive polarization with the naked eye, a phenomenon called "Haidinger's brushes". Look at a polarized background (such as a computer monitor showing white in a dark room). Staring into the field, one may be able to see a faint blue / yellow pattern, which is related to the polarization of the screen.
A video on how the polarizer works might be interesting. In my grade school days, we were taught that the filters work like a series of tiny slits, as if light waves are like ripples in a rope. Whilst that's a useful analogy, it's a bit deceptive.
The problem is I already made that video, like, 6 years ago. Went down to the molecular level and everything. It's from back in my early days before I really figured out what I was doing.
Beware, that you use polarized sunglasses to see the rainbow colors, and not the 3D glasses, you will get at the movies to see 3D movies in 3D. The latter are compared of two layers of different polarizing glassed put together. I was puzzled by the strange effects of these glasses in comparison of polarized sunglasses, before I found the solution. Maybe a good idea, to do a video about these 3D glasses too. It is very surprising, and interesting.
You're mostly looking at stress gradients not stress with those patterns. There are tests for molded in stress such as impact tests and chemically induced ones at various concentrations and temperatures. Plastic parts might be molded in tools that are below zero to heated with hot oil to control process time and molded in stress. Also some parts are post mold annealed. Another great video btw. I never tried but I wonder if a clear styrene plastic spoon would show less lines if it was put in a pot of hot water and allowed to cool slowly?
Adam Savage was able to use one of those glass breaking hammers with no trouble in one of the Underwater Car episodes of MythBusters. I think the reason you had trouble is because your pane was just flapping around in the breeze, whereas a car window is held rigidly by the door frame. Also, your pane appears to be a quarter inch thick, which is twice as thick as typical car glazing.
@@ScienceAsylum Well played. I remember that Adam wasn't able to kick out the window with steel toed boots; the key is the rigid pane with a focused impact. I'm not positive, but I think he also had good results with a spring loaded center punch.
You might want to pop in a note: First you state front windshield are made of annealed glass at 5:43, but later state car windshields are tempered glass.
I've noticed this when I have something made of clear plastic and I can see a reflection of my computer's screen in it, the reflection is rainbow colored. I always guessed it must have something to do with polarization but I wasn't sure. This also happens a little bit with sunlight.
You'll have to do a little better to convince me to wear these glasses. I fear we might end up in a long drawn out street fight where you force me to wear them and me refusing to do so. Things will get ugly, lots of blood and pain, but you might win in the end and i will see your point of view. (referencing "They Live", obviously)
Man, the algorithm sure didn't favor this video. Only reason I found it was because I realized you haven't uploaded in a while so I went to the videos page and saw this was uploaded 8 days ago 😞
Yes it's called tempered glass, but the temper process itself can be used in both ways. Annealling and hardening. At least in the german language it can.
I'm wondering if there is a 3 polarizers and quantum effects in this video (not seen it all yet). Two polarizers at 90 degree angles block light, but insert a 3rd polarizer in between at 45 deg angle and they don't block the light any more.
It is not only when your car goes into water that tempered car glass can save your life. I used to work in a trauma center as a custodian thirty years ago before air bags were mandated. Car accident victims would come in with superficial wounds on their foreheads from where they’d hit the windshield. I’d clean up these tiny jagged cubes of bloody glass. As gross as that sounds the patients were rarely had much more than a minor concussion injury. Motorcycles on the other hand . . .
Science Asylum: Did you know that polarized lenses let you see rainbows in clear objects? Me, deciding prescription sunglasses are too expensive and simply wearing small sunglasses behind my normal glasses when I drive on sunny days: Ohhhhhhhhh yeah
Dang! Great video, as always I'll use it in my physics classes when I teach wave optics. If you keep this up, I'll just need to have my students watch you instead of listening to me (I know they'd rather do that....) Also, an automatic center punch will usually shatter tempered glass when used in thge center. I had the misfortune of learning this when my car was burglarized a few years ago.....
The windshield is not tempered glass. If it were, then any chip in it would cause the whole thing to fracture into tiny pieces (which could cause a crash for sudden loss of visibility). Instead, it is 2 sheets of annealed glass, with a sheet of thick durable plastic between them, basically keeping them glued together. Either sheet of glass can break, but will be held in place. Also, it is very difficult to punch even a small hole through the windshield. It is far easier to break through a side window, which is tempered glass. If you cannot break the side window, then try to defeat the windshield seal by attacking the corner of the windshield.
@@ScienceAsylum, yeah, sorry, that was easy to miss. Also easy to forget that you said it, especially since I try always to withhold commenting until I've watched the whole video. And now that I went back and watched that part again, I couldn't understand how I missed that, UNTIL I backed it up a few seconds more, where you got tongue tied, twice. I guess my thoughts lingered on that a few seconds, causing me to miss the next statement altogether. What can you do.
The first 1,000 people to use the link will get a 1 month free trial of Skillshare: skl.sh/thescienceasylum09221
*Correction:* The segment about safety hammers has been removed from this video. Some safety hammers do actually work very well. Thanks to diligent commenters, I've since done an experiment and released a correction video: ruclips.net/video/0tmLh_eSpQU/видео.html
*Clarification:* The side windows and _rear_ windshield are tempered. The _front_ windshield is annealed. Sorry for any confusion.
are you familiar with a strange experiment i saw a loooong time ago on a youtube video where - IF i remember correctly- the setup was two perpendicular polarized filters which of course resulted in black (no light passing) but then when adding a third filter in series, light magically appeared again!! I really hoped you would touch onto it cause i cannot remember the explanation!
Thank you for the video anyway
@@sadderwhiskeymann I don't think there is an explanation... just another mystery like quantum entanglement that everyone thinks should be impossible. Would still love to see a video if he hasn't already.
@@Server0750 The glass is cooled with a bunch of air nozzles. Each spot is where one of the nozzles was.
Can I use this technique to see the stress pattern in a Prince Rupert's drop?
@@Luiz_Alberto.P.K Yes, you should see the rainbow pattern in a Prince Rupert's drop.
4:25 That "chip" in the edge of the protractor is where the plastic was injected into the mold. That's why the stress is oriented to it.
4:35 That "crack" likely indicates that the plastic was injected near the hidden upper corner of the triangle, flowing around both sides. The "crack" is where the 2 flow fronts came together.
Yes, I spent a few years in the injection molding industry.
🤔 Interesting! I'm not an engineer, so these kinds of things just don't occur to me. Thanks for sharing.
@@ScienceAsylum Yes, as jursamaj points out, it's not a crack but a knit line. They are usually not a problem if the moulding tool and the moulding process are done well, but they can still be a line of weakness that may need to be considered in critical applications.
Thanks for the injection molding tidbit. I would guess that quality control inspectors though (not engineers) use the polarization in production runs, if at all. Engineers would use it it for design. Although I've seen it used in research papers (scientists) on stress concentrations which might then be referenced by engineers for design.
Injection molding of plastic is now so ubiquitous yet it still seems like materials sorcery when closely examined. Same feeling you get when you make your own nylon. Mind blown.
@@JohnDoeHZ In my (admittedly limited) experience, polarimetry isn't very useful in production facilities, because most plastic parts aren't transparent. There is a lot of information we used based on such research, but I don't recall my plant even having any polarimetry equipment.
Hello. Nick, I did not expect this topic here on the channel but as an engineer for material science I aprove!
I would like to ad a short explanation how tempered glass is made and how it works, for people who would like to know/understand.
Very hot glass (the car window!) is quickly cooled from the outside. When this happens the outer parts of the glass starts to quickly cool and when things cool they generally shrink a bit. No problem yet because most of the body of glass is still hot and can easily adapt to the shrinking outer layer. But soon the inner volume starts to cool down too and at that point the outer layer is stiff and can not easily change. But the inner parts need to shrink! (The atomic forces who hold the material together are very powerful and demanding)
What happens is that the inner volume contracts but the outer layer can not move and this causes the outer layer to be compressed (more than it wants) and the inner volume to be pulled apart (because the outer layer does not move much).
So why does this help against damage? Home experiment! Take a bunch of pillows and put them together on the table. Punch them and watch them fly through your room. NOw have another person take the pillows and press them together with both hands. Punch the pillows again and.. the pillows stay where they are.
The compression forces in the outer layer function like the hands of the person holding the pillows. To "push the glass apart" you need to overcome these forces first which makes tempered glass much more resistant against damage.
I hope this helps.
Thanks for the extra detail!
(Also, I want other people to love polarizers as much as I do, so the glass thing helps make polarizers relevant to people's lives.)
Fascinating, and makes so much sense, thanks! I always wondered why the stress makes it stronger and resistant to breaking.
Nice explanation! 👍 Would it have been better to call it 'pressured glass'?
@@localverse Or "pre-stressed glass".
Well explained!
The sharp point tools actually work quite well, your problem is your glass isn't secured, and just flexes and bounces away. In a car, the glass is secured by the doorframe, with extra pressure from the water pushing in. There's lots of youtube videos of people testing tools, most of them work just fine, with the best having a spring-loaded punch similar to one you'd use to mark metal prior to drilling.
^agree to this with a ton of experience behind it.
As a firefighter, taking tempered glass is done often on vehicles. A lot of tools that folks expect to readily break glass doesn’t often work but the easiest victor against tempered glass is always a small, focused point.
Was going to say the same thing.
I'm surprised that he didn't figure that out himself.
Pointy end of hammer, not the blunt end 👌
It reminded me of an episode of Shark Tank where someone first wanted to show how easy it was to break through a door, but humorously failed to to so because the door was secured to a movable metal frame instead of an actual wall.
"Light is literally all we can see" is so simple a statement that it sounds silly. But since I've been going through your videos on cosmology I've gotten a handle on dark matter and understand that light doesn't interact with everything. It's... uncomfortable knowing that some ideas that we take for granted (like light being the mechanism through which we observe ALL things) hide ridiculous facts about how the universe really works.
Technically, the only thing we can ever see is the electrochemical patterns moving around in the visual cortex. It's so strange to Conceive that we don't see "out", but everything we see, all of our surroundings, even the sky, is built within the mind based on sensory input. When you see something "over there", the distance between you and that object is probably real, but it's perceived within the confines of your skull. Even the position of yourself, your body, and it's location relative to the environment, is a projection of what may or may not exist "out there".
It really messes with the mind! Lol!
@@bryandraughn9830 Kinda like we are just bundles of neurons driving bone mechs powered by meat motors with a skin casing.
I mean is touch not also observation
@@bryandraughn9830 Very true and to make that more obvious, make sure to understand that there is no brown or magenta in the color spectrum (let's call it a rainbow). Colors (by that I mean the sensation we call colors) are made up by our mind. Not to mention that you perceive different colors depending on the words you have in your language.
We can easily extend this to "almost everything we can see is electromagnetic fenomena". We only know about gravity (apart from touch, of course) because the fotons expose the objects positions in the space due reflexion or absorption (hence the acceleration too).
Moreover, Touch is also an electromagnetic phenomenon, LoL
Took me quite a few years to find out not everyone can see stress-patterns without any tools. Turns out only a very small percentage of people can actually see them.
Needless to say, I got even more interested in them!
Opticians use polarizes all the time to check if the lenses in your glasses are mounted properly!
Wait, you mean, your eyes act like a polarizer? You can see them naturally?
Are there any artists that paint with that in mind, so people would need polarizers to properly see all of the painting, while a very small percentage of people would see that naturally?
@@mlok4216 some people can to a limited degree, not like an octopus though.
@@localverse I don't know if there are, but what a great niche for someone.
I trained myself to see Haidinger's brush, which is a visible manifestation of linearly polarized light that you can see without a polarizer. It looks like a very faint yellow and blue bow-tie pattern near the center of your field of vision--you can see it by looking at a white LCD screen and gradually tilting your head, so the pattern changes enough that your brain won't edit it out. The blue parts lie along the axis of the electric field, and the yellow parts along the axis of the magnetic field. Once you know what to look for, you can see it in the sky, because that light is somewhat linearly polarized.
Next, do a video with three polarizers. Whenever I see more light coming out when adding a filter, I really "feel" quantum mechanics.
Wanted to make the same comment. Hope he sees this.
@@mirador698 me too
I wanted to place this comment.
I recently finished a first year module in Material Science and we literally did this exact experiment! Your videos were a huge inspiration for me to study an undergraduate course in Physics. Thank you so much!
Sandwiching something in between two polarizers is an useful tool to pathologists since it allows them to differentiate between different types of microscopic materials based on their molecular isotropy (or anisotropy). Like, it is used all the time in microscopic tissue sections to detect amyloid, a class of misfolded protein that causes amyloidosis. Also there are uses of polarizing microscopy in geology to tell apart different rocks. You could do an episode on such practical uses of polarized light microscopy. It could be interesting, at least to me.
Science fact of the day
I love how Nick keeps the bloopers! 😄😄 Pure genius!
I'm pretty sure you struggled to crack the tempered glass because you allowed it to move, preventing the kinetic energy from turning into pressure (stress). When you hit the corner, the glass was pinned to the floor at the contact point, it couldn't move, so all the kinetic energy was turned into pressure energy, exceeding the internal allowable at that point.
you are partially correct . due to how tempered glass is made the edges of the glass cool down faster than the rest of the piece making it ........ less tempered . hitting tempered glass edge on can break it just as easy as annealed glass .
@@logiticalresponse9574 I believe prince Rrupert's drop is en extreme example of this.
@@57thorns indubitably
"Light is all we can see." This is quite beautiful.
Unknown to most of us, humans actually do have some capacity to tell polarized light apart from unpolarized. A blank sheet of paper will simply be white, uniformly and equally, no surprise there. But on a standard LCD or OLED monitor showing a blank white canvas, by really focusing and also tilting your head every so often, you can see a blob of yellow and blue in the shape of a bowtie. It's slightly different from person to person, some people see patches where the screen is slightly darker but don't see the colors, some people do see the colors with no change in brightness, and sometimes the effect can randomly disappear.
nick has already a video on it... you could find it here on YT
It's called haidinger's brush
Thanks for letting me know how to experiment with this phenomenon using just my sunglasses and a pc monitor! On the other hand, my wife does not appreciate it greatly because I am searching through the kitchen for every transparent bowl and gathering them on my desk for inspection.
😂
Tip. If you break a spark plug and collect the broken ceramic pieces that result, simply toss them at a tempered window, the window shatters with hardly any impact at all. Something about the harmonics I suppose. But just a little shard of that broken ceramic casually tossed at the window and it shatters. Might be worth looking into and doing a video to confirm exactly how that works.
Interesting 🤔. I'll have to look into that.
Hmm, i think Adam and Jamie had it. But its difficult find on so many videos.
Always love your vids. You always tend to explain things in a way I can always understand which is sometimes difficult to find. And sitting down for a little science lesson kinda reminds me of the old days with Mr. Wizard when I was little. Keep up the great work!
I just love it when you say "It's okay to be a little crazy".
This *really* makes me want to see the Slo Mo Guys revisit the Breaking Glass video with polarizing filters. I wanna see those colors change *as* the glass breaks.
My camera isn't high-speed enough for that, but the Slow Mo guys could definitely pull it off. I'd love to see it.
@@ScienceAsylum I bet Destin with smarter every day would be willing to collaborate with you, yall both a couple weirdos
@@mandelabrein8116 Their energies would vibe perfectly.
Your videos put more "light" in our world! 🤩
playing with polarizers for the first time in physics class was cool. if i recall, a really cool object to look at under this effect is a prince ruperts drop.
this vid shall be a wonderful addition to my "birefringe" playlist.
We've used this technique to find defects in door glass for residential ovens where I work. That tempered glass has to be perfect, or it can shatter during cooking cycles. Don't want that to happen in somebody's kitchen.. There are some REALLY cool stress patterns in that glass, too. You'd never know without using a polarized filter like this.
I already tried it before the video's end. Amazing experiment. My daughter loved it and so did I.
I recognise those patterns in the Plastic equipment (protractor, rulers etc.) we had in High School. I wonder if there was a enough Polarisation going on in my glasses to account for this. Nice to finally have an explanation for what it was.
I worked for about 6 years with Alvin and Mortimer Marks, the inventors of polarizing films. Amazing the things that can be done with polarizing light, including making old time 2D movies into 3D movies, polarizing photovoltaics ( LUMELOID), stealth materials ( absorbing UV visible and IR light).
i really like your videos! I was going to do a linkedin post about this over the pandemic, but never got around to it. Couple of notes: "stress rings" are usually called fringes, like when looking at the moire effect and probably more technically correct to call strain rings since it's really the spacing of the molecules that alters the polarization of the light. You can actually buy off the shelf polarizers and materials that are basically calibrated to measure stress (you put the clear stuff over a thing and let it stretch) and a color coded chart is provided to quantify the stress of each color. Something not touched on your video, which I'm probably just telling you something you already know, but if you rotate your polarizer you can determine the directions of the stress in the material also. Birefringence is cool!!!!!!!!!!!! lol, nice job, you're doing awesome stuff.
Someone on s/askphysics asked how RUclipsrs like Veratasium and kurzgesagt were as far as videos go. Turns out Fermi labs, pbs spacetime, and you were in many of the responders top 3. I totally agree!!!
Thanks for letting me know!
Not that any of them were bad rather being more convoluted for the sake of being convoluted. I'm sure most of us appreciate the clarity you and couple others bring. Easier to follow and understand which means easier to learn. Make like a fraction and simplify it lol.
And you're welcome =)
I always wondered what these points are on the rear window when i look in the rear view mirror with my polarised glasses on, thanks nick.
Glad I could help 🤓
to those curious, you can see polarized light yourself! physics girl has a video on haidinger’s brush, and its orientation in your vision is dependant on the polarization of light coming in. i’ve trained my ability to see the pattern enough that i can easily spot it in the clear blue sky 90° away from the sun, with the yellow lobes in the pattern pointing to where the sun is. you can also see it while looking through polarized sunglasses or an LCD screen as mentioned in the video here.
This video clearly says light polarization can be seen given some conditions and gives examples where these conditions holds.
I was actually wondering about these since Ive seen these in my car with my polarized sunglasses. Thanks!
tempering glass is based on heat dilation (as opposed to metal where its about the crystalline structure grain size, glass doesnt have a crystalline structure),
its heated up to a point where its sortof soft, and then cooled quickly. when its heated the glass dilates. when its cooled from surface first, the surface shrinks and hardens. after that the insides start to shrink too, but as they do, it drags the surface with it creating pressure and resulting in a denser surface.
the cooling is done via pressurized air, and each of those dots is where an air nozzle is blowing on the glass.
@@yunthi wow, very interesting, thank you for the comment
Not sure if someone mentioned but windshields are made of laminated glass (1 piece of plastic sandwiched between 2 thin pieces of glass). This is important because of several factors, for example, if a rock or large object hit your windshield it won’t got through. Second the crack are lines so you can still see and drive. The temperate glass are used on side windows, that is why on smash and grab you will find a thousand piece of glass. On a car accident it allows the windows to be broken so you can be removed and also prevent sharp glass from hitting you.
I got some Oakley "fishing" glasses a few years ago. I don't fish, but the mirrored reflection was a and that's what I wanted :V Anyway, they have STRONG polarization and when pairing them with a motorcycle helmet it makes a cool but sometimes disorienting effect and ofc it's related to polarization! First off, cars change color with their angle to you. They're dark when coming at you, but shift to a lighter color as they approach 90° to your vision centerline. WATER is super trippy, and can appear doubled at some angles. I got prescription lenses so I hardly wear those glasses any more but I was walking my dog by a pond and noticed "holy crap! I can see all the fish!". Product functions as intended.
Cool! I just tried the glasses from the 3D movie theater and a cell phone as the source of polarized light and I can see stress in the plastics as well.
I've always wondered what those circles in automotive glass represented. Thanks for answering it.
You're very welcome 🤓
@@ScienceAsylum
I actually just noticed these in my car the other day, and was curious, but not enough to go and look it up. Now, I know!
When I was a graduate student I lived in a literal hole in the ground--a studio apartment in my landlord's basement, with a sliding glass door in a small well below ground level. The door was double-glazed with tempered glass. One wintry evening, I was away from home when the temperature suddenly dropped from around freezing to down near zero Fahrenheit. When I came home, I found that the outer pane of the glass door had completely shattered into those tiny gravel-sized pieces. Thermal contraction had apparently caused those internal stresses to let loose and break the glass. Fortunately, the inner pane was still intact--but most of the shattered outer pane was still holding together loosely like a sagging vertical jigsaw puzzle that was obstructing the door from opening, so I had to knock it all away to open the door. Since the remaining pane was a less effective insulator, I had a chilly couple of nights until the landlord could get the door fixed.
Dang! I just Googled it and, apparently, it's not uncommon for doorwall glass to do that. Seems like maybe they shouldn't be using tempered glass in doorwalls.
Try having a monitor screen all white while in a dark room, have a pair of polarising lenses so you can see either the screen lit up or go dark, turn the lenses so it's dark, then grab a full clear water bottle and look at it through the lense. It looks amazing, looks like it's completely self luminescent, it'll look lot up and maybe you'll see other colours too
The sky can become kinda funky with polarized sunglasses too. I have noticed that if I look away from the sun ( north at noon in the northern hemisphere ) I can make the blue of the sky darken by rotating my glasses. The effect doesn't affect the look of the clouds so they pop out. Sometimes the effect doesn't happen and I have no clue why.
Not even sure why the side of the sky away from the sun seems to have some polarizing effect.
Thats apparently how birds tell directions from what i read in an article a while back
The polarized sky tells them where is north.
I remember when I found on the street a broken game toy and I was able to take the screen apart. It had two transparent plastic pieces and I was astonished when I turned the two plastic pieces and it became completely black! 😯
Back when these filters weren't glued in, I'd take my watch/calculator apart and flip the polarizers, which created white-on-black displays.
I appreciate that this video was designed with cell phone orientation in mind. I happen to hold my phone on it's side.
7:35 the glass shards won't just be smaller, they'll be less sharp, too.
On a side note car windshields are also laminated. When the tempered glass shatters it will stick to a stretchy substance and act like a net. Kinda like how softer steel is used to reinforce hard and brittle concrete.
To get a pretty fascinating Effect One needs a Pair Polarisation Glasses with round Glasses. Plop One Out, turn it a few Degrees - I have One at Horizontal and One 45° turned to the Left and plop it Back and One gets a 3D Effect in Reality or even more!!
I know not really, but pretty fascinating and revealing!
Works best during the Day :)
Haidinger's brush is crazy, it's something you can pretty much always see when you're staring at a computer screen, but unless someone tells you it exists, you probably never notice.
Did you know you can see UV light if your cornea is removed? See for example the painter Monet and how his paintings turned more blue after the removal of his lens in one eye.
Monet's surgery meant the entire lens of his left eye had to be removed, leaving him with what's called aphakia, or the absence of an eye lens.
due to how tempered glass is made the edges cool down faster than the rest of the piece . hitting the glass edge on will break it just as easy as annealed glass . there is also an in between temp and plate (annealed) called heat strengthed that breaks similar to temp but in bigger pieces in a less chaotic fasion
I tested it with polarising glasses from a 3d cinema and wow it's so cool.
Your tempered pane of glass was able to flex and absorb the impacts of your attempts to break it. :P
Spring-loaded center punch is a cheap no nonsense emergency window breaking tool to keep in your car, and they absolutely do work. You can find 'em in any big box home improvement store. Just put the tip to the glass and PUSH. The spring-loaded impact mechanism does all the work. Takes very little strength, and you don't need space to wind up and swing. You don't need one of those fancy hammers unless you get one that also has a razor blade for cutting your seat belt strap, because seat belts CAN and sometimes DO jam and can't be unbuckled after a hard enough shock to the latch. Then it's worth it to buy the 2-in-1 tool so you don't have to think about digging out two tools and then using each one individually in an emergency when seconds literally matter.
I work with tempered glass all day, and boy am I glad this stuff has been invented. It's actually pretty fun to smash them on the ground with some PPE on. Very hard to get cut with this stuff (relative to annealed glass anyways).
Yeah, I had eye goggles and a mouth covering on for safety. Don't want that stuff in my mouth or eyes. Yikes!
The critical thing about breaking the tempered glass with the special pointed hammer is keeping the pane rigid, as if it were in a car door, yours flexed and dissipated a lot of the energy required at the point of the hammer. But otherwise, you're right, even a moderate bang on the edge will shatter tempered glass.
Hello Nick, I am new to your channel and find your detailed explanations extremely helpful!
Would you mind doing an episode explaining why solids have color? I think there are a few different absorption mechanisms out there, like F-centre or van der Waals. A video about them would be amazing. Thanks in advance!
Thanks Nick Sir for making such amazing and complicate topic videos in such simple language
I'm just in 12th grade and ur videos really help me a lot to deeply under my School textbook topics very well
Usually school teacher just explain us how it works but not why only it works ☹️
U r the one who tell why only it works 😁
And not joking but I showoff infront of my friends about knowledge u gave to me especially 'Gravity is not a force'video 😂
But unfortunately I can't donate or join ur membership 😕😕 as i'm just 18 and my parents don't allow it too😕
But I watch ur videos regularly to gain more knowledge and commenting it just to tell u about that 😊😊
I was able to see these colours since I was a kid - without polarising glasses .. I assumed everybody could.
I've also been able to see colour tones vividly where others were saying it's the same colour .. found out I'm a male with tetra-chromatic vision .. .. like a unicorn - discarded by society for being different .. .. I've learned to keep such things to myself and pretend I'm just ordinary Joe and use my not-so-super-powers to excel in life .. only to find that it pisses off people .. words like "who do you think you are?!" - echo in my not-so-identical memory .. .. oh well .. this is my life and it's beautiful.
Tempered glass also keeps you from getting blended by broken windows in a car wreck, or even just after hitting bigger bumps in the road. As far as those crash hammers go, the cheap ones are too soft to work because they deform slightly on impact, and shouldn't be allowed on the market considering the implications. Better ones will have hardened steel or carbide tips to focus the impulse into a smaller spot, and spring loaded center punches are very popular in emergency services for their ability to break auto glass in a controlled way
I don't understand this cheap "window breakers" are even legal. I'm going to look for a standard hammer design but with a pointy tip. Best of both worlds.
Oh I need to try this on transparent FFF (3D) prints.
A few cars do have tempered windshields, with spots and rainbow coloring all over, that is vey noticeable from the outside at least on certain days.
I've noticed those spots before and realized they were caused by polarization, but I couldn't search exactly why... And finally here it is!
Glad I could help 🙂
@@ScienceAsylum on a second thought, I 'm not convinced: why, in a car windshield, are the stresses so perfectly ordered in a lattice fashion. Moreover, why we don't need polarized light (as in the case of the ruler, with the LCD screen) but just a pair of sunglasses are enough??
Awesome video, I kinda always wondered about the spots, although I'm wondering if they might be from the molds themselves, seeing how auto glass is made, the molds are not what you'd think.
They basically are a "Table" for lack of a better word, made of a grid of rollers that can be adjusted up or down to set the curve of the glass.
And I'm thinking since the spots basically line up with the grid of the rollers if the glass cools faster at the contact points creating those stresses the polarization allows us to see.
If that makes sense.
Also
As someone currently working in the auto glass industry as a tech, and for some time now, a few corrections: (to the best of my knowledge and understanding)
A: On a lot of newer vehicles the front door glass is now laminated annealed glass, like the windshield. Meaning it's not going to break into a thousand tiny pieces, it will hold very strong even if broken and take a lot of effort to make fully fail. However the rear door glass, or backglass should be tempered.
The way to tell is to look at the glass, there should (by law) be markings on EVERY piece of glass that states laminated or tempered along with other info like brand etc.
B: Tempered glass is very unlikely to shatter from the force of impact going into a body of water, unless it hits head on, you should 100% have a glass breaking hammer similar to what he showed in your vehicle..period. You should also have a seatbelt cutter as well.
C: As to the point above, the reason the hammer failed in your test is because it was not secured on the sides allowing it to dissipate the energy. These hammers are intended to break tempered auto glass in an emergency to gain access in, or out of the vehicle, that glass will be secured on all sides and will break. He is 100% correct that the edge of any glass is the weakest point.
D: Not so much a correction but if you find yourself a body of water and sinking, the very 1st thing to do is roll down the window, power windows are not likely to immediately fail as there is water proofing, the inside of your door takes on moister normally.
E: Purely a nit pick, there is only ONE windshield in a vehicle (unless it's a split windshield) everything else is a front door glass, rear door glass, Back glass, vent glass (opens as part of the door but does not roll up or down) quarter glass ( stationary glass that does not roll up or down, and does not open with a door.)
The clear ruler and triangle was a great example of internal stresses. I am taking a strength of materials course at my university right now. It was difficult to understand internal stresses and the concept did not make sense to me.
Neato! Now I want to look at all my plastic stuff under polarized light. Too bad I don't have any polarized sunglasses, though.
Have a look at tiny crystals in a microscope with a set of polarizing filters, one below the sample one somewhere above (I cut a piece of sunglasses to cover the occular lense). Crystals from the cubic system are somewhat disappointing - compared to other crystal systems. But it is a world of wonderful beauty.
Thanks!
I still didn’t understand how more filters could produce more light? Because the first one is obviously already filtered out most light with other polarizations….
You actually can see polarized light without any tool. On a white computer screen is it visible when you tilting your head from one side to the other and back. In the center of your view will a blue-yellow figure apear, called "Haidinger brushes". It is very weak, but in front of the white screen clearly to see. On a very clear evening sky, maybe one hour before sunset you can see these Haidinger brushes 90 degrees offset to the sun likewise too. And even like on your computer screen you have to tilt your head from left to right and back again. The first try is maybe a little hard, but with some practice it will clearly appear.
This is similar to holding a powerful magnet near an old CRT TV and watching the electron deflection change as you move it around. Can't see the electrons but you can see the effects they have when diverted to the wrong phosphors. Edit: Note that the two phenomena are completely unrelated, but not as much as you'd think since electrons are waves too and have an oscillation "direction".
Amazing nick ❤️
Got to try this!
This man is genius 👍
From wanna be immortal to a giant ball of stress.
I'm a diverse individual.
@@ScienceAsylum thanks for the reply😊😊
There is another way of shattering tempered glass.
A broken piece of ceramic, like a broken spark plug, can shatter tempered glass when thrown. It might be the hardness of it combined with how small of a point ceramics can get when broken.
It would be cool to see the stresses in a prince Rupert drop
I love polarization and dispersion so much I carry around polarizing filters and a diffraction grating. :-)
It's cool to see the spectrum of different light sources. E.g. "white" LEDs
I've heard that striking tempered glass with the ceramic of a broken spark plug can cause the glass to shatter easily. But I have not tried to verify that.
All that and no timeline needed!
Car window glass is mandated to be tempered by law to prevent injury during and after vehicle collisions. It has nothing to do with water. Car manufacturers nearly universally did this due to the obvious safety benefits and minimal additional cost well before mandated by government bodies.
Thanks for sharing
I don't know which hammers you are talking about at around 07:00 but the small red hammers designed for emergencies definitely do work to break tempered glass quickly. If I had a car, I would have one of those near at hand.
I'm hearing this a lot in the comments. I must have a cheap useless hammers. Will be trying alternatives soon 👍
Me gettting between my monitor and the sunglasses to check my stress points: As I predicted, I resemble a polka dot!
You can see the stress rainbow on roolers without polar filter, yes it's easier to see with them, though.
I saw those spots on a whindshield of a Trabant, don't tell me they used tempered glass on the whindshields. The whindshield are made with laminated glasses, normally, prewenting someone sheater it skull on them in an accident, and holding to shards togethet when the glass shateres.
You must be in the portion of the population that can see polarized light.
Thank you for the video.
You're welcome 🤓
It is (just barely) possible to perceive polarization with the naked eye, a phenomenon called "Haidinger's brushes". Look at a polarized background (such as a computer monitor showing white in a dark room). Staring into the field, one may be able to see a faint blue / yellow pattern, which is related to the polarization of the screen.
It's my understanding that only a small portion of the population can see Haidinger's brush. It's not something everyone can do.
A video on how the polarizer works might be interesting.
In my grade school days, we were taught that the filters work like a series of tiny slits, as if light waves are like ripples in a rope.
Whilst that's a useful analogy, it's a bit deceptive.
The problem is I already made that video, like, 6 years ago. Went down to the molecular level and everything. It's from back in my early days before I really figured out what I was doing.
@@ScienceAsylum I shall go look for it. Thanks.
Beware, that you use polarized sunglasses to see the rainbow colors, and not the 3D glasses, you will get at the movies to see 3D movies in 3D. The latter are compared of two layers of different polarizing glassed put together. I was puzzled by the strange effects of these glasses in comparison of polarized sunglasses, before I found the solution. Maybe a good idea, to do a video about these 3D glasses too. It is very surprising, and interesting.
look at a prince ruppert drop with that!
I am going to try this stress-viewing experiment. Thanks for the reminder of something I saw long ago... What about CIRCULAR polarization though?
Circular polarization is more difficult to explain. It's more fundamental than linear.
You're mostly looking at stress gradients not stress with those patterns. There are tests for molded in stress such as impact tests and chemically induced ones at various concentrations and temperatures. Plastic parts might be molded in tools that are below zero to heated with hot oil to control process time and molded in stress. Also some parts are post mold annealed. Another great video btw. I never tried but I wonder if a clear styrene plastic spoon would show less lines if it was put in a pot of hot water and allowed to cool slowly?
Adam Savage was able to use one of those glass breaking hammers with no trouble in one of the Underwater Car episodes of MythBusters. I think the reason you had trouble is because your pane was just flapping around in the breeze, whereas a car window is held rigidly by the door frame. Also, your pane appears to be a quarter inch thick, which is twice as thick as typical car glazing.
I'm going to be retrying it soon with a variety of items. It could just be that my hammer was a cheap knockoff.
@@ScienceAsylum Well played.
I remember that Adam wasn't able to kick out the window with steel toed boots; the key is the rigid pane with a focused impact. I'm not positive, but I think he also had good results with a spring loaded center punch.
It would be good to see the stress patterns in a prince Rupert’s drop.
You might want to pop in a note: First you state front windshield are made of annealed glass at 5:43, but later state car windshields are tempered glass.
The side and rear windows are tempered. The windshield is annealed.
@@ScienceAsylum 🙏 for the clarity.
I've noticed this when I have something made of clear plastic and I can see a reflection of my computer's screen in it, the reflection is rainbow colored. I always guessed it must have something to do with polarization but I wasn't sure. This also happens a little bit with sunlight.
I've never noticed the reflection 😱. I need to try it now!
You'll have to do a little better to convince me to wear these glasses.
I fear we might end up in a long drawn out street fight where you force me to wear them and me refusing to do so.
Things will get ugly, lots of blood and pain, but you might win in the end and i will see your point of view.
(referencing "They Live", obviously)
Man, the algorithm sure didn't favor this video. Only reason I found it was because I realized you haven't uploaded in a while so I went to the videos page and saw this was uploaded 8 days ago 😞
I thought for sure this one would do well. I'm not sure what happened. Maybe there's no way to convince people to care about polarizers 🤷♂️
We could absolutely use more polarization of the light, and less polarization of the society :)
Yes it's called tempered glass, but the temper process itself can be used in both ways. Annealling and hardening. At least in the german language it can.
I'm wondering if there is a 3 polarizers and quantum effects in this video (not seen it all yet). Two polarizers at 90 degree angles block light, but insert a 3rd polarizer in between at 45 deg angle and they don't block the light any more.
It is not only when your car goes into water that tempered car glass can save your life. I used to work in a trauma center as a custodian thirty years ago before air bags were mandated. Car accident victims would come in with superficial wounds on their foreheads from where they’d hit the windshield. I’d clean up these tiny jagged cubes of bloody glass. As gross as that sounds the patients were rarely had much more than a minor concussion injury.
Motorcycles on the other hand . . .
Great videos, thanks!
I carry a Starrett 18C automatic center punch in my truck's console for emergency window removal.
Good thinking 👍
Science Asylum: Did you know that polarized lenses let you see rainbows in clear objects?
Me, deciding prescription sunglasses are too expensive and simply wearing small sunglasses behind my normal glasses when I drive on sunny days: Ohhhhhhhhh yeah
Dang! Great video, as always I'll use it in my physics classes when I teach wave optics. If you keep this up, I'll just need to have my students watch you instead of listening to me (I know they'd rather do that....)
Also, an automatic center punch will usually shatter tempered glass when used in thge center. I had the misfortune of learning this when my car was burglarized a few years ago.....
This video will stay up, but I make no promises that the thumbnail or title won't change.
The windshield is not tempered glass. If it were, then any chip in it would cause the whole thing to fracture into tiny pieces (which could cause a crash for sudden loss of visibility). Instead, it is 2 sheets of annealed glass, with a sheet of thick durable plastic between them, basically keeping them glued together. Either sheet of glass can break, but will be held in place. Also, it is very difficult to punch even a small hole through the windshield. It is far easier to break through a side window, which is tempered glass. If you cannot break the side window, then try to defeat the windshield seal by attacking the corner of the windshield.
*"The windshield is not tempered glass."*
Yeah, I say that at 5:42
@@ScienceAsylum, yeah, sorry, that was easy to miss. Also easy to forget that you said it, especially since I try always to withhold commenting until I've watched the whole video. And now that I went back and watched that part again, I couldn't understand how I missed that, UNTIL I backed it up a few seconds more, where you got tongue tied, twice. I guess my thoughts lingered on that a few seconds, causing me to miss the next statement altogether. What can you do.
It’s: light you CAN see with WITH sunglasses. Nick is totally trying to confuse me with this dopple negative and his beautiful blue eyes 🤓