I'm glad sci show changed the thumbnails to an all green border. Back when the borders had red at the bottom, it made it look like all videos had been partially watched.
Old glass was often spun to make it flat, which resulted in the thicker bases, and also is the reason some windows have knobbly round bits in there somewhere as decoration, as those were where the pole that spun the glass was originally attached... :)
I’m sceptical of this claim, wouldn’t that put a bulge around the entire perimeter of the pane? I was under the impression that glass making was just imprecise, and was thicker at one end due to an inability to make it flat.
For flat "plate" glass, for windows, yeah. That is called "crown" glass. A blob of molten glass was placed in the middle of a disc that was then spun on its axis. This caused the molten glass to flatten out due to "centrifugal" force (That term DOES have meaning here.) and create a mostly circular "flat" sheet of glass. However, the surface was thinnest at the edge and thickest in the center. So it came up to a "crown". Paved roads today have a "crown" in the center if they are on an ostensibly flat run. That helps rain slough off to the edges. The crown glass was then cut into window sized pieces and the thicker edge, as Hank says, became the bottom edge. Your description is mostly about glass containers that are spin to create them. The center of their bases is where the "punty" attached. Usually these are first "blown" with a blow stick and then spin later to finish them off.
Pitch is a substance that appears solid but is actually an extremely viscous liquid. There's the famous pitch drop experiment where a lump of pitch has been placed in a funnel and over the course of decades has been dripping into the beaker underneath
@Battlesheep: You forgot the strangest part: the drop in the original experiment has never been caught on video. Each time, there's been a local earthquake, or the power went out, or there was a solar storm, or some other thing that prevented the recording equipment from capturing the drop separating from the main body. This has happened often and consistently enough, and with enough different causes each time, that I'm starting to think that the very inability is a minor SCP.
Not all old time glass panes are installed with the thick bit down. Some are installed with the thick bit up, or on the sides. Those thick bits are still there and unchanged hundreds of years later
Yup. Professional installers normally chose to put the thicker part down as it is thought to be more stable long-term. Source: I worked with stained glass for 14 months and my boss had been in the business for 30 years.
My wife has lived in the same house for the last 50 years, (it was built 120 years ago) and the glass, much of it original, now is more brittle than it was when she was a child.
If you ask a guy from southern Germany (not Bavaria, the other southern Germany called schwabia), he would tell you that butt is feet, and so is everything between your toes and your butt, because the word in their dialect for every thing in between hip and toes is "Fiers" (that's not how you normally spell it, just to emphasise the way it's pronounced), which stems from Füße and means feet. So butt is feet, fight me! ;)
The best scishow episodes are the ones where it's clear Hank is also learning/excited about the topic. See "5 Most Dangerous Chemicals" "The concrete...was on FIRE!!"
Is Hank EVER not excited? Imagine the first time he eats a blueberry waffle from the Pocahontas Pancake House in Virginia Beach. He'll not only melt, he'll energetically describe the melting process.
@@engineclinic He is right though. He already said that glass is not liquid, it is considered as "amorphous solid". Go look for more info rather than just trying to act smart
I recently helped move my grandmother out of her house, and her bathroom mirrors were distorted, which my family members attributed to the glass “dripping” over so much time.
The Big Questions: 1. Why is there something rather than nothing? 2. What is consciousness and how does it arise from ordinary physical matter? 3. Glass.
« Why » is not a scientific question « Consciousness » does not really exist, it is an illusion, a feeling that there is an « I », stable over time. An illusion generated by our material brains. « Glass » - well, no idea.
@@sebastienh1100 We do not know enough about consciousness to even make that claim, sure there is the brainactivity but we have no clue which part would create our sense of self or view of the world, especially with the variety we see in brains. Why would be the start of a hypothesis and should then be refined to exclude other possibilities. it's good that we don't know everything, it keeps us busy.
So, is it possible that glass is originally solid, but because its not a crystal, its material structure is more easily changed by reacting to the environmental effect, such as heating from direct exposure to the sunlight? Like we know that crystal sugar & cotton candy is sugar, just have some difference in structure, like diamond & coal, or in thus case, sand and glass. If its in crystalline structure, it is strong, rigid, definitely a solid: crystal sugar, diamond, sand If its in amorphous structure, it is weak, softer, easily breakable/affected by external effect: cotton candy (easily melt by body heat/humidity), coal (easily burn & crushed), glass (easily breakable & possibly melt by sunlight/trickle down by gravity, just very very slowly?)
@@IamJustaSimpleMan it doesn't say the the opposite it litteral says the no consences and some definitions do define it as a type liquid. All it debucked is the different thinkness was not from flowing but from pre float glass construction methods, and that even if it is like pitch there not been enough time for the thick Ness changencoming fromit liquid properties
I don't think it's adequate to liken the tensile stress glass is subjected to on formation to a liquid's surface tension. You can poke your finger inside a liquid (provided you can overcome the surface tension) and once you pull it out the surface returns to equilibrium, but unless you're Neo tripping on some red pills, you cannot do the same to glass. If you overcome the tension in glass, it fractures and doesn't come back together.
@@moscanaveia not necessarily. When cutting glass. Once you score the glass if you don’t break it quickly enough the surface tension evens back out and you won’t get a clean break.
I have always loved watching people making glass of all types and it's great to learn about such a beautiful and essential activity and no one seems to appreciate it for what it is. Thankyou for satisfying my curiosity and teaching me something that I always thought about.
Now I need to build a time machine to take me back to 597 when Canterbury Cathedral was built so I can measure the glass thickness at top and bottom of a stained glass window then return to now and see how thickness has changed over 1424 years.
Considering the oldest windows at Canterbury date from 1130-1160, you'd probably be wasting your time... Which doesn't matter if you have a time machine I suppose! While you're there may as well ask the glaziers what their technique for making and fitting the glass is/was - that'd answer the question partly at least. Oh and say hi to Æthelberht and Augustine for me!
We've also made very little headway into whether glasses which have precisely 50% of their volume filled are half full or half empty. Lots of science still to be done.
@Michael: Actually, that's pretty much solved if the glass isn't in a total vacuum: it's half full of whatever is filling it halfway, and half full of the ambient atmosphere.
That's a question that needs context. Imo if you fill the glass halfway then it's half full and if you start with a full glass and get to the middle it's half empty.
Its a matter of perspective. Is the glass in the act of being poured, or just been poured? Its half full. Was the glass being drunk/spilled/drained? Its half empty. Its half full if your filling it, half empty if your emptying it.
@@whatever12643 Purely in terms of helping people to see that the same substance have have multiple forms of "solid". A lollipop is sugar in an amorphous solid form, while rock candy is sugar in a crystalline form. It's not a complete / perfect analogy because of the additives that are often added in the making of lollipops to inhibit crystal growth. But "Amethyst" is just colored quartz; this is pretty analogous to colored / flavored rock candy.
@@falcon.heavy. maybe its not random, but has a pattern that is so huge that you cant see it repeated in a single specimen. This is a joke, of course, but maybe....
Just a mention, the sector of technology that studies the transmission and diffusion of light within the glass, is another mind-blowing vastly sector, not mentioned in the video. Just adding little amount of other elements can change the refraction index, and what else. Whoever wear spectacles learned how adding a bit of lanthanum (at great monetary cost) can make the glasses much thinner while keeping the same dioptric power. Great video, thanks!
Im surprised they missed the fact that flat glass back in the day was poured, and then spun to make a flat sheet. The spinning made the outside edge thicker and the middle thinner, by a small margin.
No, it's the opposite. The center was thicker, and the outside edge thinner. But then the glass was cut to fit windows, so it ended up with one edge thicker. Just google pictures of crown glass, and in a lot you can see the circular bull's eye where the pole was attached to spin the glass, and it's thicker and therefore less transparent.
@@Jatt2613 crown glass was for lenses, not windows (generally, it can be made into a window, but will warp light). For windows they would pour it on a table that spun, centrifugal forces would make the majority of the glass go to the outside edge, meaning the center was thin, the edges were thick, and it would then be cut to fit the needed window frame.
Consider telescope mirrors and lenses that are made of glass. To produce good images, the surfaces of these optics have to be finished to a fraction of a wavelength of visible light. Were glass a liquid, telescope optics would slowly become distorted and the images they produce would degrade over time. Yet telescopes manufactured more than a century ago still produce superb astronomical images. (Of course, this doesn't rule out the possibility that glass "flows" over geologic time periods.)
Glas is basically a high viscosity liquid. It does not emit heat of solidification. There is no phase shift, bor a shift in the heat capacity, like in other materials, hence it is a superfreezing liquid.
I've heard the term "infinitely slow moving liquid". - I've been a believer since finding a pane of glass of a once flat window glass panel in the attic (of a house in Silverton, Colorado, 9,300 ft. elevation - early 80s). This pane of glass was leaning against the underside of the steep roof, and being at an angle, the pane itself had developed a bent in it of some 25° or so. Trippy as heck. Tin roof, over one by sheathing. It got very hot up there regularly, then very cold, winters -20° nights was no rarity. It had been up there many decades.
Interestingly glasses when formed from undercooled liquids actually form different densities of the glass when cooled down at different rates. Also when it is cooled down quickly, it will slowly relax itself into the state you would get by cooling it slower. For this reason, many glasslike materials such as many plastics actually change dimensions during their lifetime, causing the thing made from it to also 'decay'.
Looking at natural volcanic glass such as obsidian (or impact glass) this seems to be the case as well with glass it is called devirtification whereas with natural glass the devirtification forms spherulites a circular (or spherical) reconfiguration of the glass into a fine grain crystalline form. There are lots of effects that effect the rate devitrification plays out particularly the composition (i.e. impurities) and the ambient conditions at which it is kept but ultimately it seems to be a process that occurs most readily given something to nucleate around so any existing crystal structure or dust on the glass causes it to be more likely to devitrify which for most glass looks like a whitish film that propagates outwards. So it seems to be a much more general process of decaying from metastable states to more stable structures. Seems safe to say these things don't last on geologic timescales.
not to be pedantic but old window glass wasn't 'poured'. that would result in an uneven finish and potentially cracking from asymmetrical cooling. old glass was blown into a ball, rolled into a cylinder, cut, then unfurled into a sheet. that's why stained glass windows are made of many parts; it's hard to make big sheets of glass by hand. it's also hard to temper large pieces of glass without an electric kiln.
It's been a while since I took a Materials Science class, but I'm pretty sure "metallic glass" is not silica glass with metal in it, but metal with a "glassy" atomic structure.
Yeah different things but not mutually exclusive A metal is any substance composed of fermions where the outer(valence) electrons get stuck in higher energy orbitals below the temperature and pressure where they are energetically favorable (i.e. the atoms have more electrons than they "want" in their outer valence shell this cause them to form a shared pool or "sea" of degenerate electrons known as metallic bonding. In his sense a metal can be any phase of matter so long as the electrons are in a degenerate phase according to the Pauli exclusion principal ranging from familiar iron lead zinc to metallic hydrogen or oxygen under high pressures and even the more exotic material which makes up a white dwarf star's composition. A glass is just an amorphous solid which is typically a metastable state where the atoms were frozen quickly so they couldn't fully crystalize. In either case if you make a substance which exhibits both properties you can call it a metallic glass regardless of what those compounds are.
I would use "metallic" to describe a non-metal in a metallic state. I would use "metal glass" to describe a metal alloy exhibiting glassy properties. I'm not sure what the current industry practice is, but that seems the clearest lexical distinction. There might be "metallic glass" made entirely of non-metal atoms. One might even consider silicate glass to be "metallic glass". Certainly silicon's metalloid nature contributes to the properties of regular glass. Granted, like everything, if you look too closely you have to start sorting things into finer categories to avoid blurring the previous order.
Thank you sci show for continuing to ask yourselves all those childish questions I keep holding on from the days of my youth, keep learning , keep unearthing new knowledge..¿
As a glassblower this is super fascinating, my obsession with glass started because I was able to see this material in such a different state than I was used to.
My physics teacher at the university said it's a liquid, now we know more. That was 40 years ago, glad we have learned even more once again. Thanks Hank and all involved in making SciShow!
If we assume that glass used to be installed with the thicker edge down, there must be some examples somewhere of glass that was installed the other way around. A new glass installer makes a mistake now and then, or someone wasn't paying attention on the job, or the way the glass was cut plus the way old building aren't quite square would mean that the glass fit better with the thicker side up. Have any examples of this been found?
Yes, it's actually not uncommon. Multi-pane windows (where all the individual panes are sealed in a lead or wooden frame) that are intact and unmodified since original production, where there are one or two panes that are otherwise identical to the rest... only the thicker end is at the top. And if you look at modern produced examples using old glass making techniques (such as at historical sites that have a living history component), and you look at the glass panes they make, they look exactly like the ones in centuries old original windows in terms of waviness and asymmetrical thickness. And they are not only new, in many cases they haven't even been stored or mounted upright yet.
old mouthblown glass, specially when its made thin tends to curl a bit. its first blown into a bubble. then using a plane its made into a cylinder. the cylinder ends are cut off, and then its cut open after which it goes into a straightening kiln. thicker heavier parts tend to stay straight while thinner parts tend to curl up as it cools down again. during installation, you put the straight side down, nail it in place and then press the curved bit against the frame with a runner, nail that in place. so unless you are doing it on a table. its generally easier to install the thick part down. modern mouthblown glass is generally made a bit thicker overall so it isnt an issue really anymore.
As someone with a passing knowledge of physics and chemistry, there seems to be a pretty straightforward hypothesis for why glass forms an amorphous structure. Materials tend to change state starting at a single point and then spreading out from there, with the small region with the new state making the surrounding molecules more likely to change state and join them -- nucleation. Since the growth of the nucleation points happens molecule-by-molecule, we can consider each one independently, at least as a first approximation. So, looking just at one molecule joining the fused state, consider how it attaches to the bulk. There is a spectrum of possible orientations that it could take, each with its own unique energy level. In the simple case, you could plot this energy level as a curve, though more complicated molecules would have energy surfaces in higher dimensions. The energy curve/surface will have different magnitudes at different configurations, leading to hills and valleys. In the simplest case, it could end up looking like a parabola: as energy is slowly removed from the system, the newly added molecule will tend to relax "downhill", towards the minimum of the parabola, and thus the new molecule will have a well-defined optimum orientation in the structure, causing a crystal to form. In a more complex case, the energy curve will have multiple minima, which could differ from each other in their absolute energy, separated by barriers of higher energy states. If one minimum is still considerably deeper/wider than the others, it will still be the preferred final state as energy is removed, though it is possible for the molecule to get stuck in one of the other local minima. But if the energy barriers between the minima are considerably greater than the **energy difference between the minima**, the preference for one minimum over another decreases. So for glasses, you can hypothesize that the energy landscape is relatively flat -- there are multiple minima of similar energy and each additional molecule added to the bulk chooses one of the minima randomly based on its initial conditions, causing the resulting structure to be random. If the energy of the system is reduced *very* slowly, though, thermal fluctuations will be much more able to differentiate between the energy levels of the minima (and overcome the barriers between them), kicking molecules out of local minima into the global minimum with much more regularity. Thus, silica forms a glass when cooled quickly, but a crystal when cooled slowly.
states of matter are parameter clouds. They arent meaningfully discint from each other. It's a liquid if it acts like one, its not if its not. States don't exist in physical space. Theyre just tendency labels we use for the convenience of our pattern recognition. Discussing the nuance of categorization is useful, but its important to remember its a discussion of categorization, not of character. Teh physical object doesn't necessarily reflect how we view it
I love science. Scientists really are like "ok so in a million billion years it'll either become a puddle or a crystal and it's really anyone's guess lmao"
But will Scotty’s “transparent aluminum”, once he reveals it to someone in the near future so he can take a few whales forward into the future, be confused as a liquid? 🧐😎
"Transparent aluminum" is pretty close to the sapphire glass that Apple wanted to use on the iPhone. We can make it, just doing large sizes and at scale is really tough
i wonder what kind of structure glass would make it it was made in micro gravity? Given we need to cool glass down fast here on earth or Gravity could mess with the shape or in the case of flat glass Gravity is always interacting with it as it cools.
In chemistry, we cool our synthetic products very slowly, the rule of thumb is the slower the better because you are maximising the time to allow the crystals to form their regular structure. In cases like cooling ice cream it is better to rapidly cool it with liquid nitrogen because it prevents the sugars from crystallising which would otherwise be like glass. There was an article of a concerned parent reporting their child eating glass in a chocolate bar. It was later revealed that the crystal was not actually glass but sugar that had not been cooled properly.
I’m curious now… for the old stained glass windows, the more intricate, the more metal is used within the window. In times of very high temperaatured or long periods of direct sunlight, could the metal heat high enough to allow very slow change?
probably not. Just trying to fire clay into pottery is a finnicky and specialized process, and if i remember correctly, clay fires around 1000 degrees (of an unknown unit XD). it could change if it was hit by a volcano, but it wouldnt do us any good cause we couldnt observe it lol
For an engineer, whenever the shear strength of a chunk of material is not zero or negligibly small, then it is solid. According to this criterion: glass is solid.
@@nahidhkurdi6740 that depending on the shear force you apply a polymer can start acting like a rigid material then change his mechanical behavior to a elastic and viscoelastic.
Love the show, thank you all. I am in the family candy business. In researching candy science I read once that hard candy, ie candy canes, is/are actually a super high viscosity liquid. True? Perhaps a good future show. A general principle I would also like to further understand is the higher one heats a "bob" (candy term for sugar/corn syrup starting point) the harder the end product will be. So caramels heat to 240F ish and are "soft." A few degrees higher will yeild a harder caramel product. Hard candy is around 320F. Think werthers original. Would love to understand this more. Thanks again for the work you do!
depends but i think it could be something akin to a yield stress that differentiates the two? You can get fluids with a yield stress though. I think the main thing to understand is that in this case, Glass has covalent bonds which provide the strength for its structure which makes it act solid (of course conventional soda lime glass has some ionic character as well but same logic). I believe its kind of the strength of the bonds that to some degree determines whether it acts more like a fluid/solid.
@@stephaanjacques2269 Do amorphous solids have a latent heat of fusion? I mean, the way it's described, it just sounds like a liquid, whose viscosity goes up and up as it cools. It doesn't seem like there's a "phase change," per se.
@@bcubed72 yea i dont believe that glass has a latent heat of fusion. Good point. Personally for glass I think it something similar to martensite. Where its cooled really quickly and has to settle into a metastable state as the molecules cant diffuse into a stable structure.
Macroscopically it is reasonable to consider a solid, but at the molecular level glass behaves like a supercooled liquid, presenting an amorphous microstructure. If the processing conditions are favorable, a crystalline glass (solid) can be obtained, called glass ceramic.
Thanks for "shattering" this old myth about stained glass windows being thicker at the bottom. I have yet to see an actual example (or a photo) of such a piece of glass.
@@jimmyc3238 i dont know why there arent any photos from a side view when you search it up, but in many photos the middke of the glass has a round large shape, which is where it was spun around from
This does not explain how an old glass container once broke to us, and we found that the upper part was very thin and fragile, while on the bottom, It was really thick, more than an inch in some places. It really looked as if most of the glass was run down the walls of the container, and only surface tension kept the upper part intact.
what color was the glass the main way glass seems to change over time is devitrification where it slowly crystalizes one molecular bond at a time nucleating outwards from existing crystalline structure. The odds of this occurring seem dependent on both the impurities in the glass and the environment it was stored in. Dust in particular seems to be a big problem for preserving old glass because of this process with removal of the devitrified parts via sanding of something similar needed to prevent it from spreading.
I wouldn't be surprised if he did (he or Tasting History). But it might have gotten lost in that constantly-speaking-never-taking-a-breath style like what Michael MJD does.
When I was studying Bio at university, electron microscopy was brand new and samples had to be encased in a plastic rod. We were told that in order to cut sufficiently thin slices from that rod, we could use a diamond or a glass knife, which was a freshly broken piece of glass. We were told that diamond knives were more desirable because the glass knife would loose it's edge due to the slow flowing of the glass.
Probably shouldn't take physics or engineering lessons from a biologist. Diamond is much harder and much less brittle than glass. The glass edge will abrade long before it "flows" (bends). Is copper a liquid? Lead? I would try using a knife made of those materials before concluding this anecdote suggests glass is a liquid.
There's also something patented as Metalloy, caled previously LiquidMetal. By mixing certain metal atoms, an alloy is formed, but because of their different properties the alloy doesn't for crystals, it stay "vitreous" -glasslike. As glass, the formation is tricky, you know you got it when it becomes a mirror when cooled. Which is cool 😃 It has properties unlike common metal alloys, some desirable, some not so much. Could be a nice Video to make Hank!
Hank - I understand what you mean in context. However, metals in glass do not yield "metallic glass". Metallic glass is a new and different kind of material - en.wikipedia.org/wiki/Amorphous_metal?wprov=sfla1. Please be careful with choice of words. Not trying to be an ass. Just pointing out stuff.
Awesome content 👌 If I may, I'll share what I've learned randomly before, just in case there's merit to it. I learned that many glasses exist because they are formulated on purpose to actually be glass, and not crystallize on purpose. The key is to introduce impurities, or make a full out mixture of different materials which don't crystallize the same way, and upon cooling at a wide range of rates, the nature of the mixture disrupts the crystallization process, inhibiting a natural order of molecular arrangement. Try shaking a box of different size balls together and see if a pattern tries to dominate... less likely. Pitch and toffee behave like what glass might be likened to, by being possibly a version of non-newtonian fluid. They can bend or flow like an extremely viscous liquid, but if any force exceeds a certain threshold, the material fractures instead of yielding faster. Without enough impurities, I'm not aware that pure quartz will solidify like glass without a crystalline texture, although some lamp bulbs are labeled as quartz, so either I'm mistaken there or they add some kind of impurities... 🤔
Even thought *most* of your sources talk about the glass transition, the video didn't really cover it. It's a fascinating area where we can really probe what we mean by 'solid' and 'liquid', which is pretty crucial to answering the question in the title! At low temperature and high strain rate, a vitrified material should act as a solid. At high temperature and low strain rate, the same material should act as a liquid. And there's some region in between where weird things happen that I still don't really understand despite spending a week at a course learning about just that one thing. I'm not saying everything has already been explained, but that the questions left to be answered are far more interesting that they seem based on this video, and some of them have some very curious leads so far which were not discussed here.
I don't know if anything has actually changed, but I noticed that the lighting is particularly nice in this video-so clean and even, but still providing contrast in all the right places. Great work! The animated graphic at 4:24 is a little distracting :/
"Thanks team for putting together this episode that answered so many questions that I have had for so long" The answer of course being that there actually isn't really an answer yet! ...even still, it's still the only answer we have and so we shall take that as an answer.
Why doesn't chocolate set hard unless you temper it? Why do the bonds break and how does tempering (controlled temperature or done by adding more cocoa butter) work exactly?
What about the old glass vases they found that were under a heavy vessel that were flattened? From Roman times I believe. This was in Scientific American.
Something to consider, crystals usually require some form of contaminant seed to start forming (think supercooled water for example). I suggest the stable structures form near to contaminants, so more crud more crystals. The least contaminated portions remain amorphous. Depends on cooling time as well since cooling is not even across the structure. A slower cooling results in more time for the crystallization to reach further away from seed sites converting amorphous to crystalline. Flash freeze it, and the only thing you get is amorphous. Now if we can only figure out how to super chill molten glass with just the right amount of metalized crud 🤔
The question isn't whether or not glass is a liquid; it's whether or not glass is a FLUID. Liquid is a state of matter and is as Hank described while a FLUID can be a liquid or a gas. These two states of matter have in common the ability to flow. Liquid water flows in a stream. Oxygen in its gas form flows in the wind. The argument has always been: "Is glass a FLUID?"
Glassy metals are and, for well over 30 years have, been used for turbine blades in aircraft engines. The technology is usually known as "single crystal" technology. As stated in the video the key is in how the molten metal is cooled.
A single crystal is as far from a glass as you can get. As the name implies, it's one mass with the same ordered units in the same orientation throughout. A glass is a disordered mass without repeating ordered units anywhere.
I saw the thumbnail and thought it was about honey. I read the title and was intrigued because I've never heard about that mystery. So thanks TH-cam for continuously pushing this in my Recommended until I read the title. And I'm glad I did. This was really interesting.
I'm glad sci show changed the thumbnails to an all green border. Back when the borders had red at the bottom, it made it look like all videos had been partially watched.
I remember the time before the red watched stripe, I think it just took everyone a (long) while to update their thumbnails to accommodate it.
Yeah, i noticed that too. Also wondered if it was intentional or an oversight.
Yassssss
I’m so glad I’m not the only one who was bothered by that red line
They've never had red on the bottom as far as I can tell, only on the sides. Did they change every thumbnail or something?
Gosh, figuring out the mysteries of glass sounds like it's gonna be a real pane.
Very punny
Yes, but eventually the mysteries of glass will become clear.
I for one think glass research is blown way out of proportion - they should just cut it.
GET IT?!
@@KarlBunker yep, thus shattering previous theories
Old glass was often spun to make it flat, which resulted in the thicker bases, and also is the reason some windows have knobbly round bits in there somewhere as decoration, as those were where the pole that spun the glass was originally attached... :)
I’m sceptical of this claim, wouldn’t that put a bulge around the entire perimeter of the pane? I was under the impression that glass making was just imprecise, and was thicker at one end due to an inability to make it flat.
For flat "plate" glass, for windows, yeah. That is called "crown" glass.
A blob of molten glass was placed in the middle of a disc that was then spun on its axis. This caused the molten glass to flatten out due to "centrifugal" force (That term DOES have meaning here.) and create a mostly circular "flat" sheet of glass. However, the surface was thinnest at the edge and thickest in the center. So it came up to a "crown". Paved roads today have a "crown" in the center if they are on an ostensibly flat run. That helps rain slough off to the edges.
The crown glass was then cut into window sized pieces and the thicker edge, as Hank says, became the bottom edge.
Your description is mostly about glass containers that are spin to create them. The center of their bases is where the "punty" attached. Usually these are first "blown" with a blow stick and then spin later to finish them off.
That’s true
1q
I've noticed older glass windows become thicker at the bottom over a period of decades. Same with most antique jars.
To paraphrase The Hitchhiker’s Guide to the Galaxy: glass is something almost, but not quite, entirely unlike a liquid.
nice pull. i was just re-reading this last week.
Hmm...glass must be akin to the waiter's notebook.
I forgot that one
Thank you!
Pitch is a substance that appears solid but is actually an extremely viscous liquid. There's the famous pitch drop experiment where a lump of pitch has been placed in a funnel and over the course of decades has been dripping into the beaker underneath
And the most interesting thing is that nobody saw the drop falling
My astronomy professor in college said that glass is just like pitch but slower. It drove me up the wall.
I just saw it earlier! maybe we were recommended the same video the "top longest experiment"?
@Battlesheep: You forgot the strangest part: the drop in the original experiment has never been caught on video. Each time, there's been a local earthquake, or the power went out, or there was a solar storm, or some other thing that prevented the recording equipment from capturing the drop separating from the main body.
This has happened often and consistently enough, and with enough different causes each time, that I'm starting to think that the very inability is a minor SCP.
I remember this. I think they got another drip a few years ago, but can't ever seem to get it on camera.
Not all old time glass panes are installed with the thick bit down. Some are installed with the thick bit up, or on the sides. Those thick bits are still there and unchanged hundreds of years later
Yup. Professional installers normally chose to put the thicker part down as it is thought to be more stable long-term. Source: I worked with stained glass for 14 months and my boss had been in the business for 30 years.
also old telescope lenses would suffer heavily from glass flowing, but they are all still good to use
My wife has lived in the same house for the last 50 years, (it was built 120 years ago) and the glass, much of it original, now is more brittle than it was when she was a child.
@@simonwaldock9689 exposure to elements, scratches, cleaning products, etc can weaken glass over time
@@felixc543 Cleaning products have got nothing on glass, except perhaps if you're using lye to clean your windows, which you really shouldn't.
Now that this is answered, can we move on to the more pressing question of "Are Butts Legs?"
Yes they are
If you ask a guy from southern Germany (not Bavaria, the other southern Germany called schwabia), he would tell you that butt is feet, and so is everything between your toes and your butt, because the word in their dialect for every thing in between hip and toes is "Fiers" (that's not how you normally spell it, just to emphasise the way it's pronounced), which stems from Füße and means feet.
So butt is feet, fight me! ;)
are hot dogs sandwiches?
@@ZeWitchKid Food theory did a video of epic proportions about this very question in case you are interested
@@IamJustaSimpleMan
I'm Northern German and have no idea what you are talking about or how that even makes sense lol
Is glass a liquid?
Well, it really depends on the temperature...
Room temperature huh, depends where the room is. In Alaska, in Arizona, on the sun?
In molten silicon dioxide even considered glass? Hmm...
Is glass wet?
@@Alfuro not wet, but really really moist.
@@thomasesr NOICE
The best scishow episodes are the ones where it's clear Hank is also learning/excited about the topic. See "5 Most Dangerous Chemicals"
"The concrete...was on FIRE!!"
Is Hank EVER not excited? Imagine the first time he eats a blueberry waffle from the Pocahontas Pancake House in Virginia Beach. He'll not only melt, he'll energetically describe the melting process.
That is my favorite one
@@ackket4660 Mine tooooooooo
I have watched that video far too many times hahaha
And have been known to just randomly exclaim that exact line too
Everyone who isn't hank is just filler for when they can't get hank
ahah yess The flammable concrete was quite a magical moment to experience with Hank
I remember the crash course chem video where hank yelled at those who thought glass was a liquid.
Hank isn't as smart as he thinks he is. Glass is indeed a liquid.
@@engineclinic At least he's aware of it
@@engineclinic He is right though. He already said that glass is not liquid, it is considered as "amorphous solid". Go look for more info rather than just trying to act smart
@@KAThamMaoChai it is a liquid. His methodology is incorrect.
If you just give up the fight and call it a liquid all the mysteries and unanswered question go away.
"Metallic glass"? You mean like Transparent Aluminium?
Not exactly.
If you cool it right, it can in fact mean transparent aluminum, yup 😁
I guess not everyone here got the reference...
Isn't that what they used in Star Trek IV to house the whale?
From across the classroom: "Thanks, Glenn!" 👍
I recently helped move my grandmother out of her house, and her bathroom mirrors were distorted, which my family members attributed to the glass “dripping” over so much time.
The Big Questions: 1. Why is there something rather than nothing? 2. What is consciousness and how does it arise from ordinary physical matter? 3. Glass.
Basically
"Why" questions are pointless
You need Kurzgezagt vids in your life if it's not already! I think 1 and 2 are both word for word video titles!
« Why » is not a scientific question
« Consciousness » does not really exist, it is an illusion, a feeling that there is an « I », stable over time. An illusion generated by our material brains.
« Glass » - well, no idea.
@@sebastienh1100 We do not know enough about consciousness to even make that claim, sure there is the brainactivity but we have no clue which part would create our sense of self or view of the world, especially with the variety we see in brains. Why would be the start of a hypothesis and should then be refined to exclude other possibilities. it's good that we don't know everything, it keeps us busy.
I appreciate you guys teaching us new stuff all the time. However even more so, I appreciate you pointing out current mysteries. Keep them coming!
Thank you! As a glassblower I have had to debunk this myth over and over for the last 20 years.
To sad that a lot of people here are only reading the title and are just reproducing this myth, despite the video stating the opposite 😕
So, is it possible that glass is originally solid, but because its not a crystal, its material structure is more easily changed by reacting to the environmental effect, such as heating from direct exposure to the sunlight?
Like we know that crystal sugar & cotton candy is sugar, just have some difference in structure, like diamond & coal, or in thus case, sand and glass.
If its in crystalline structure, it is strong, rigid, definitely a solid: crystal sugar, diamond, sand
If its in amorphous structure, it is weak, softer, easily breakable/affected by external effect: cotton candy (easily melt by body heat/humidity), coal (easily burn & crushed), glass (easily breakable & possibly melt by sunlight/trickle down by gravity, just very very slowly?)
@@IamJustaSimpleMan it doesn't say the the opposite it litteral says the no consences and some definitions do define it as a type liquid. All it debucked is the different thinkness was not from flowing but from pre float glass construction methods, and that even if it is like pitch there not been enough time for the thick Ness changencoming fromit liquid properties
@@geraldgrenier8132 different "thinkness" indeed.
Amen! Part of my lampwork class spiel involves whacking the table with a rod of glass and declaring "this is a solid."
I'm glad Hank said "higgledy piggledy." You just don't hear that enough.
He: Is glass a liquid ?
My Textbook: Glass is an "amorphous solid".
Me: I thought glass is a "glass".
That's... Too simple 🙄🤣
Someone trying to be philosophical: Is the glass half full or half empty?
Smart-ass: It’s an amorphous solid.
Real smart-ass: neither, the glass is too big.
@@easy_s3351
An engineer, the glass is always full with a varying gas / liquid ratio
@@diceman199 True, an empty glass is full of air
@@easy_s3351 Wine lover, top that up for me would you :-)
The amorphous structure in glass has surface tension like a liquid too. You have to take it into account when cutting it.
Do you think the surface tension has anything to do with the amorphous structure?
I don't think it's adequate to liken the tensile stress glass is subjected to on formation to a liquid's surface tension. You can poke your finger inside a liquid (provided you can overcome the surface tension) and once you pull it out the surface returns to equilibrium, but unless you're Neo tripping on some red pills, you cannot do the same to glass. If you overcome the tension in glass, it fractures and doesn't come back together.
@@moscanaveia not necessarily. When cutting glass. Once you score the glass if you don’t break it quickly enough the surface tension evens back out and you won’t get a clean break.
I have always loved watching people making glass of all types and it's great to learn about such a beautiful and essential activity and no one seems to appreciate it for what it is. Thankyou for satisfying my curiosity and teaching me something that I always thought about.
Now I need to build a time machine to take me back to 597 when Canterbury Cathedral was built so I can measure the glass thickness at top and bottom of a stained glass window then return to now and see how thickness has changed over 1424 years.
Considering the oldest windows at Canterbury date from 1130-1160, you'd probably be wasting your time... Which doesn't matter if you have a time machine I suppose!
While you're there may as well ask the glaziers what their technique for making and fitting the glass is/was - that'd answer the question partly at least. Oh and say hi to Æthelberht and Augustine for me!
@@RoganGunn Good point. Progress on the time machine is slow. So far it will only go forwards in time at the same rate I'm ageing.
We've also made very little headway into whether glasses which have precisely 50% of their volume filled are half full or half empty. Lots of science still to be done.
@Michael: Actually, that's pretty much solved if the glass isn't in a total vacuum: it's half full of whatever is filling it halfway, and half full of the ambient atmosphere.
That's a question that needs context. Imo if you fill the glass halfway then it's half full and if you start with a full glass and get to the middle it's half empty.
Dear Optimist and Pessimist,
While you were arguing I stole the glass of water.
-The Opportunist
Its a matter of perspective. Is the glass in the act of being poured, or just been poured? Its half full.
Was the glass being drunk/spilled/drained? Its half empty.
Its half full if your filling it, half empty if your emptying it.
given that matter is mostly empty space, i'd say that a full glass is substantially empty.
A (somewhat) useful analogy: Glass is like a lollipop, while silica is like rock candy.
@@whatever12643 He means they're both yummy, so crunch away.
@@whatever12643 Purely in terms of helping people to see that the same substance have have multiple forms of "solid". A lollipop is sugar in an amorphous solid form, while rock candy is sugar in a crystalline form. It's not a complete / perfect analogy because of the additives that are often added in the making of lollipops to inhibit crystal growth. But "Amethyst" is just colored quartz; this is pretty analogous to colored / flavored rock candy.
Isnt it always so cool when scishow adresses a subject that is part of what you study or work on?
It’s a crystal! The unit cell is just infinitely large
It's actually not a crystal. Crystals have a crystalline structure whereas glass has a random arrangement of molecules.
@@falcon.heavy. woosh
@@falcon.heavy. maybe its not random, but has a pattern that is so huge that you cant see it repeated in a single specimen.
This is a joke, of course, but maybe....
@Kris Nicholson no it won't.
Glass isn't a crystal because it has no short range order. It does have medium and long range order which means it isn't random.
Just a mention, the sector of technology that studies the transmission and diffusion of light within the glass, is another mind-blowing vastly sector, not mentioned in the video.
Just adding little amount of other elements can change the refraction index, and what else.
Whoever wear spectacles learned how adding a bit of lanthanum (at great monetary cost) can make the glasses much thinner while keeping the same dioptric power.
Great video, thanks!
Im surprised they missed the fact that flat glass back in the day was poured, and then spun to make a flat sheet. The spinning made the outside edge thicker and the middle thinner, by a small margin.
No, it's the opposite. The center was thicker, and the outside edge thinner. But then the glass was cut to fit windows, so it ended up with one edge thicker. Just google pictures of crown glass, and in a lot you can see the circular bull's eye where the pole was attached to spin the glass, and it's thicker and therefore less transparent.
@@Jatt2613 crown glass was for lenses, not windows (generally, it can be made into a window, but will warp light). For windows they would pour it on a table that spun, centrifugal forces would make the majority of the glass go to the outside edge, meaning the center was thin, the edges were thick, and it would then be cut to fit the needed window frame.
Awesome video. Really interesting
Consider telescope mirrors and lenses that are made of glass. To produce good images, the surfaces of these optics have to be finished to a fraction of a wavelength of visible light. Were glass a liquid, telescope optics would slowly become distorted and the images they produce would degrade over time. Yet telescopes manufactured more than a century ago still produce superb astronomical images. (Of course, this doesn't rule out the possibility that glass "flows" over geologic time periods.)
Geologic time, remember, it's sand, that used to be part of geology
Glas is basically a high viscosity liquid. It does not emit heat of solidification. There is no phase shift, bor a shift in the heat capacity, like in other materials, hence it is a superfreezing liquid.
Amorphous solid!
That's a good band name
AMONGUS??!?!?!!?!?!?!!!
I've heard the term "infinitely slow moving liquid". - I've been a believer since finding a pane of glass of a once flat window glass panel in the attic (of a house in Silverton, Colorado, 9,300 ft. elevation - early 80s). This pane of glass was leaning against the underside of the steep roof, and being at an angle, the pane itself had developed a bent in it of some 25° or so. Trippy as heck. Tin roof, over one by sheathing. It got very hot up there regularly, then very cold, winters -20° nights was no rarity. It had been up there many decades.
last time I tried to drink glass, it didn't go too well
I feel like that would go poorly even if it was a liquid.
@@loganrenfrow2544
what if you dissolved silica in water, does that count?
@@Broockle There’s a reason silica gel says do not eat.
@@alexwang982
.....huh..... I thought that was because it would dry you from the inside xD
But if it's in water..... adunno lol
I've been tilting this glass above my mouth for 100 years now, a drop will come any second now
Never have I appreciated more the meaning of the word semantics
Alcohol is not a solution.
It's a compound.
Scotch is a solution.
You´ve gotta love happy, enthusiastic Hank :)
Interestingly glasses when formed from undercooled liquids actually form different densities of the glass when cooled down at different rates. Also when it is cooled down quickly, it will slowly relax itself into the state you would get by cooling it slower. For this reason, many glasslike materials such as many plastics actually change dimensions during their lifetime, causing the thing made from it to also 'decay'.
Looking at natural volcanic glass such as obsidian (or impact glass) this seems to be the case as well with glass it is called devirtification whereas with natural glass the devirtification forms spherulites a circular (or spherical) reconfiguration of the glass into a fine grain crystalline form.
There are lots of effects that effect the rate devitrification plays out particularly the composition (i.e. impurities) and the ambient conditions at which it is kept but ultimately it seems to be a process that occurs most readily given something to nucleate around so any existing crystal structure or dust on the glass causes it to be more likely to devitrify which for most glass looks like a whitish film that propagates outwards.
So it seems to be a much more general process of decaying from metastable states to more stable structures. Seems safe to say these things don't last on geologic timescales.
not to be pedantic but old window glass wasn't 'poured'. that would result in an uneven finish and potentially cracking from asymmetrical cooling. old glass was blown into a ball, rolled into a cylinder, cut, then unfurled into a sheet. that's why stained glass windows are made of many parts; it's hard to make big sheets of glass by hand. it's also hard to temper large pieces of glass without an electric kiln.
That's really cool. I never knew that. Thanks!
It's been a while since I took a Materials Science class, but I'm pretty sure "metallic glass" is not silica glass with metal in it, but metal with a "glassy" atomic structure.
Well thunderf00t recently made metallic water, so anything's possible. 🤷
Yeah different things but not mutually exclusive
A metal is any substance composed of fermions where the outer(valence) electrons get stuck in higher energy orbitals below the temperature and pressure where they are energetically favorable (i.e. the atoms have more electrons than they "want" in their outer valence shell this cause them to form a shared pool or "sea" of degenerate electrons known as metallic bonding. In his sense a metal can be any phase of matter so long as the electrons are in a degenerate phase according to the Pauli exclusion principal ranging from familiar iron lead zinc to metallic hydrogen or oxygen under high pressures and even the more exotic material which makes up a white dwarf star's composition.
A glass is just an amorphous solid which is typically a metastable state where the atoms were frozen quickly so they couldn't fully crystalize.
In either case if you make a substance which exhibits both properties you can call it a metallic glass regardless of what those compounds are.
I would use "metallic" to describe a non-metal in a metallic state. I would use "metal glass" to describe a metal alloy exhibiting glassy properties. I'm not sure what the current industry practice is, but that seems the clearest lexical distinction.
There might be "metallic glass" made entirely of non-metal atoms. One might even consider silicate glass to be "metallic glass". Certainly silicon's metalloid nature contributes to the properties of regular glass.
Granted, like everything, if you look too closely you have to start sorting things into finer categories to avoid blurring the previous order.
Thank you sci show for continuing to ask yourselves all those childish questions I keep holding on from the days of my youth, keep learning , keep unearthing new knowledge..¿
So yes but no, but actually yes?
As a glassblower this is super fascinating, my obsession with glass started because I was able to see this material in such a different state than I was used to.
Further proof to the fact that things exist more in a spectrum than something with clear distinction and boundaries in this universe.
My physics teacher at the university said it's a liquid, now we know more. That was 40 years ago, glad we have learned even more once again. Thanks Hank and all involved in making SciShow!
If we assume that glass used to be installed with the thicker edge down, there must be some examples somewhere of glass that was installed the other way around. A new glass installer makes a mistake now and then, or someone wasn't paying attention on the job, or the way the glass was cut plus the way old building aren't quite square would mean that the glass fit better with the thicker side up.
Have any examples of this been found?
Yep 👍
Yes, it's actually not uncommon. Multi-pane windows (where all the individual panes are sealed in a lead or wooden frame) that are intact and unmodified since original production, where there are one or two panes that are otherwise identical to the rest... only the thicker end is at the top.
And if you look at modern produced examples using old glass making techniques (such as at historical sites that have a living history component), and you look at the glass panes they make, they look exactly like the ones in centuries old original windows in terms of waviness and asymmetrical thickness. And they are not only new, in many cases they haven't even been stored or mounted upright yet.
@@geodkyt Another piece of evidence to the myth of glass as a liquid! Thanks.
old mouthblown glass, specially when its made thin tends to curl a bit.
its first blown into a bubble. then using a plane its made into a cylinder.
the cylinder ends are cut off, and then its cut open
after which it goes into a straightening kiln.
thicker heavier parts tend to stay straight while thinner parts tend to curl up as it cools down again.
during installation, you put the straight side down, nail it in place and then press the curved bit against the frame with a runner, nail that in place.
so unless you are doing it on a table. its generally easier to install the thick part down.
modern mouthblown glass is generally made a bit thicker overall so it isnt an issue really anymore.
Yes thank you editorial staff this was very good Content.
When you use a question mark in the title you immediately show that the answer you have cannot be stated in confidence, without the question mark.
As someone with a passing knowledge of physics and chemistry, there seems to be a pretty straightforward hypothesis for why glass forms an amorphous structure. Materials tend to change state starting at a single point and then spreading out from there, with the small region with the new state making the surrounding molecules more likely to change state and join them -- nucleation. Since the growth of the nucleation points happens molecule-by-molecule, we can consider each one independently, at least as a first approximation.
So, looking just at one molecule joining the fused state, consider how it attaches to the bulk. There is a spectrum of possible orientations that it could take, each with its own unique energy level. In the simple case, you could plot this energy level as a curve, though more complicated molecules would have energy surfaces in higher dimensions. The energy curve/surface will have different magnitudes at different configurations, leading to hills and valleys. In the simplest case, it could end up looking like a parabola: as energy is slowly removed from the system, the newly added molecule will tend to relax "downhill", towards the minimum of the parabola, and thus the new molecule will have a well-defined optimum orientation in the structure, causing a crystal to form.
In a more complex case, the energy curve will have multiple minima, which could differ from each other in their absolute energy, separated by barriers of higher energy states. If one minimum is still considerably deeper/wider than the others, it will still be the preferred final state as energy is removed, though it is possible for the molecule to get stuck in one of the other local minima. But if the energy barriers between the minima are considerably greater than the **energy difference between the minima**, the preference for one minimum over another decreases.
So for glasses, you can hypothesize that the energy landscape is relatively flat -- there are multiple minima of similar energy and each additional molecule added to the bulk chooses one of the minima randomly based on its initial conditions, causing the resulting structure to be random. If the energy of the system is reduced *very* slowly, though, thermal fluctuations will be much more able to differentiate between the energy levels of the minima (and overcome the barriers between them), kicking molecules out of local minima into the global minimum with much more regularity. Thus, silica forms a glass when cooled quickly, but a crystal when cooled slowly.
Amorphous solids are cool indeed
Ha! I see what you did there.
states of matter are parameter clouds. They arent meaningfully discint from each other. It's a liquid if it acts like one, its not if its not. States don't exist in physical space. Theyre just tendency labels we use for the convenience of our pattern recognition. Discussing the nuance of categorization is useful, but its important to remember its a discussion of categorization, not of character. Teh physical object doesn't necessarily reflect how we view it
I love science. Scientists really are like "ok so in a million billion years it'll either become a puddle or a crystal and it's really anyone's guess lmao"
@Bringadingus Have you watched the video?
As a traditionally learned glass painter this vid just makes me happy!
But will Scotty’s “transparent aluminum”, once he reveals it to someone in the near future so he can take a few whales forward into the future, be confused as a liquid? 🧐😎
If by near-future, you mean 35 years ago… _Hello computer!_
(Also, just heat up some tinfoil…)
"Transparent aluminum" is pretty close to the sapphire glass that Apple wanted to use on the iPhone. We can make it, just doing large sizes and at scale is really tough
THIS is what I came to look for in the comment section!
Scotty deserves it after all this time.
Alumimiun oxy nitride. Expensive but available.
LOVE the seriousness placed against a wink joke. 😉
Man, I love chemistry! Thanks. :)
i wonder what kind of structure glass would make it it was made in micro gravity? Given we need to cool glass down fast here on earth or Gravity could mess with the shape or in the case of flat glass Gravity is always interacting with it as it cools.
Glass is cooled at different speeds to produce different types of glass, Most glass is cooled over a few hours to remove stress so not that fast.
In chemistry, we cool our synthetic products very slowly, the rule of thumb is the slower the better because you are maximising the time to allow the crystals to form their regular structure. In cases like cooling ice cream it is better to rapidly cool it with liquid nitrogen because it prevents the sugars from crystallising which would otherwise be like glass. There was an article of a concerned parent reporting their child eating glass in a chocolate bar. It was later revealed that the crystal was not actually glass but sugar that had not been cooled properly.
I’m curious now… for the old stained glass windows, the more intricate, the more metal is used within the window. In times of very high temperaatured or long periods of direct sunlight, could the metal heat high enough to allow very slow change?
Glass' melting point is between 1400°C o 1800°C, the few tens of degrees higher from hot metal wouldn't do much.
probably not. Just trying to fire clay into pottery is a finnicky and specialized process, and if i remember correctly, clay fires around 1000 degrees (of an unknown unit XD). it could change if it was hit by a volcano, but it wouldnt do us any good cause we couldnt observe it lol
@@crackedemerald4930 Soda lime glass which is your bog standard window glass starts to melt at about 700ºC and would be as soft as honey by 900ºC
“Answered so many questions “????
Looks like it asked more than it answered😀
Fascinating
"Glass is basically sand"
Centuries of innovators trying to make useable glass: Am I a joke to you?
As an enamelist--or as an artist who makes stuff with glass sticking to metal--this video was useful :).
Is “hickledy-pickledy” the scientific term?
No, that's just a slang colloquialism, but _higgledy-piggledy_ is a scientific term.
I knew it was something in between the two. But did not know the name of it before hand.
For an engineer, whenever the shear strength of a chunk of material is not zero or negligibly small, then it is solid. According to this criterion: glass is solid.
that depends since in polymers that definition isn't that simple.
@@radielkill
I do not know about a particular difficulty regarding polymers. What is that?
@@nahidhkurdi6740 that depending on the shear force you apply a polymer can start acting like a rigid material then change his mechanical behavior to a elastic and viscoelastic.
@@radielkill The shear strength is still non-negligible so the distinction holds.
Love the show, thank you all. I am in the family candy business. In researching candy science I read once that hard candy, ie candy canes, is/are actually a super high viscosity liquid. True? Perhaps a good future show. A general principle I would also like to further understand is the higher one heats a "bob" (candy term for sugar/corn syrup starting point) the harder the end product will be. So caramels heat to 240F ish and are "soft." A few degrees higher will yeild a harder caramel product. Hard candy is around 320F. Think werthers original. Would love to understand this more. Thanks again for the work you do!
Imagine in 1,000,000 years when glass is just flowing down a church and no one knows what is happening
The reason old glass panes are thicker on the bottom is the same reason that old pyramids are thicker on the bottom!
Asking in good faith: what is the difference between an "amorphous solid" and a liquid with a sufficiently high viscosity?
depends but i think it could be something akin to a yield stress that differentiates the two? You can get fluids with a yield stress though. I think the main thing to understand is that in this case, Glass has covalent bonds which provide the strength for its structure which makes it act solid (of course conventional soda lime glass has some ionic character as well but same logic). I believe its kind of the strength of the bonds that to some degree determines whether it acts more like a fluid/solid.
@@stephaanjacques2269
Do amorphous solids have a latent heat of fusion? I mean, the way it's described, it just sounds like a liquid, whose viscosity goes up and up as it cools. It doesn't seem like there's a "phase change," per se.
@@bcubed72 yea i dont believe that glass has a latent heat of fusion. Good point. Personally for glass I think it something similar to martensite. Where its cooled really quickly and has to settle into a metastable state as the molecules cant diffuse into a stable structure.
Macroscopically it is reasonable to consider a solid, but at the molecular level glass behaves like a supercooled liquid, presenting an amorphous microstructure. If the processing conditions are favorable, a crystalline glass (solid) can be obtained, called glass ceramic.
Thanks for "shattering" this old myth about stained glass windows being thicker at the bottom. I have yet to see an actual example (or a photo) of such a piece of glass.
Glass being thicker at the bottom is because of the process of how it was made
@@Helperbot-2000 Not to beat a dead horse, but again, nobody ever seems to have an actual photo of this supposed phenomenon.
@@jimmyc3238 i dont know why there arent any photos from a side view when you search it up, but in many photos the middke of the glass has a round large shape, which is where it was spun around from
This does not explain how an old glass container once broke to us, and we found that the upper part was very thin and fragile, while on the bottom, It was really thick, more than an inch in some places. It really looked as if most of the glass was run down the walls of the container, and only surface tension kept the upper part intact.
what color was the glass the main way glass seems to change over time is devitrification where it slowly crystalizes one molecular bond at a time nucleating outwards from existing crystalline structure. The odds of this occurring seem dependent on both the impurities in the glass and the environment it was stored in. Dust in particular seems to be a big problem for preserving old glass because of this process with removal of the devitrified parts via sanding of something similar needed to prevent it from spreading.
@@Dragrath1 It was a green 10 liter glass balloon made for fermenting wine.
Simple: It's a liquid with a freezing/melting point in excess of 1000* C.
by that logic everything is a liquid.
Literally the opposite to what Hank just told you.
Rocks melt too then smh
@@jonathanhendrix2925 Rocks are a liquid, obviously :)
@@jonathanhendrix2925 Yes. Yes they do. Just look at any active volcano.
2:30 Don't forget about the awesome ability of metallic glasses is that they can offer strength of metals but be transparent like glass!
Didn't Adam Ragusea mention this rabbit hole in a science video in passing once? :)
I wouldn't be surprised if he did (he or Tasting History). But it might have gotten lost in that constantly-speaking-never-taking-a-breath style like what Michael MJD does.
When I was studying Bio at university, electron microscopy was brand new and samples had to be encased in a plastic rod. We were told that in order to cut sufficiently thin slices from that rod, we could use a diamond or a glass knife, which was a freshly broken piece of glass. We were told that diamond knives were more desirable because the glass knife would loose it's edge due to the slow flowing of the glass.
Probably shouldn't take physics or engineering lessons from a biologist. Diamond is much harder and much less brittle than glass. The glass edge will abrade long before it "flows" (bends).
Is copper a liquid? Lead? I would try using a knife made of those materials before concluding this anecdote suggests glass is a liquid.
“Glass is not a Liquid…. that’s a bit like a liquid…is still a mystery.” Ummm…. Ok 🤔
I was so happy to hear _zero degrees _*_Celsius_* especially on the internet where so much is in American 😇
Glass is about as viscous as the mantle. As in basically not a liquid at all
The mantle is solid... Right?
@@MagneticSyncopation yes. Otherwise we couldn't detect earthquakes through the earth
Glass is a super-cooled liquid, isn't it?
thank you Hank. this was a myth i believed until now.
There's also something patented as Metalloy, caled previously LiquidMetal.
By mixing certain metal atoms, an alloy is formed, but because of their different properties the alloy doesn't for crystals, it stay "vitreous" -glasslike.
As glass, the formation is tricky, you know you got it when it becomes a mirror when cooled. Which is cool 😃
It has properties unlike common metal alloys, some desirable, some not so much. Could be a nice Video to make Hank!
Hank - I understand what you mean in context. However, metals in glass do not yield "metallic glass". Metallic glass is a new and different kind of material - en.wikipedia.org/wiki/Amorphous_metal?wprov=sfla1. Please be careful with choice of words.
Not trying to be an ass. Just pointing out stuff.
Solid video.
I see what you did there lol
And then there's Rupert's Drop...
Ice flows as well
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Awesome content 👌
If I may, I'll share what I've learned randomly before, just in case there's merit to it.
I learned that many glasses exist because they are formulated on purpose to actually be glass, and not crystallize on purpose. The key is to introduce impurities, or make a full out mixture of different materials which don't crystallize the same way, and upon cooling at a wide range of rates, the nature of the mixture disrupts the crystallization process, inhibiting a natural order of molecular arrangement. Try shaking a box of different size balls together and see if a pattern tries to dominate... less likely.
Pitch and toffee behave like what glass might be likened to, by being possibly a version of non-newtonian fluid. They can bend or flow like an extremely viscous liquid, but if any force exceeds a certain threshold, the material fractures instead of yielding faster.
Without enough impurities, I'm not aware that pure quartz will solidify like glass without a crystalline texture, although some lamp bulbs are labeled as quartz, so either I'm mistaken there or they add some kind of impurities... 🤔
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Got your reaction ;) so I win
@@0_toast_045 thats evidentially untrue ;)
your attention kind sir is all I needed ! 🔥
Even thought *most* of your sources talk about the glass transition, the video didn't really cover it. It's a fascinating area where we can really probe what we mean by 'solid' and 'liquid', which is pretty crucial to answering the question in the title! At low temperature and high strain rate, a vitrified material should act as a solid. At high temperature and low strain rate, the same material should act as a liquid. And there's some region in between where weird things happen that I still don't really understand despite spending a week at a course learning about just that one thing.
I'm not saying everything has already been explained, but that the questions left to be answered are far more interesting that they seem based on this video, and some of them have some very curious leads so far which were not discussed here.
I don't know if anything has actually changed, but I noticed that the lighting is particularly nice in this video-so clean and even, but still providing contrast in all the right places. Great work! The animated graphic at 4:24 is a little distracting :/
You don't know if anything has changed? You haven't noticed the massive changes to pretty much everything a couple of months ago? 🤨
Thanks, Hank!
The best science teacher I ever had told me it was a super cooled liquid and did cite the old European cathedral windows as proof of this claim.
"Thanks team for putting together this episode that answered so many questions that I have had for so long" The answer of course being that there actually isn't really an answer yet! ...even still, it's still the only answer we have and so we shall take that as an answer.
Why doesn't chocolate set hard unless you temper it? Why do the bonds break and how does tempering (controlled temperature or done by adding more cocoa butter) work exactly?
What about the old glass vases they found that were under a heavy vessel that were flattened? From Roman times I believe. This was in Scientific American.
Something to consider, crystals usually require some form of contaminant seed to start forming (think supercooled water for example). I suggest the stable structures form near to contaminants, so more crud more crystals. The least contaminated portions remain amorphous. Depends on cooling time as well since cooling is not even across the structure. A slower cooling results in more time for the crystallization to reach further away from seed sites converting amorphous to crystalline. Flash freeze it, and the only thing you get is amorphous. Now if we can only figure out how to super chill molten glass with just the right amount of metalized crud 🤔
The question isn't whether or not glass is a liquid; it's whether or not glass is a FLUID. Liquid is a state of matter and is as Hank described while a FLUID can be a liquid or a gas. These two states of matter have in common the ability to flow. Liquid water flows in a stream. Oxygen in its gas form flows in the wind.
The argument has always been: "Is glass a FLUID?"
That's like asking if molten lava is a solid. Also, there are multiple types of glass.
Glassy metals are and, for well over 30 years have, been used for turbine blades in aircraft engines. The technology is usually known as "single crystal" technology. As stated in the video the key is in how the molten metal is cooled.
A single crystal is as far from a glass as you can get. As the name implies, it's one mass with the same ordered units in the same orientation throughout. A glass is a disordered mass without repeating ordered units anywhere.
Glass is not a liquid, cat is.
I saw the thumbnail and thought it was about honey. I read the title and was intrigued because I've never heard about that mystery. So thanks TH-cam for continuously pushing this in my Recommended until I read the title. And I'm glad I did. This was really interesting.